Collections: Fortification, Part III: Castling

This is the third part of a five part (I, II) series covering some of the basics of fortifications, from city walls to field fortifications, from the ancient world through to the modern period. Last week, we used the Romans as an example to see how the needs of a given fortification changed its structure and design, from marching camps designed to protect armies on the move from sudden assaults to permanent systems of frontier fortifications designed to act as force multipliers, containing and channeling border incursions.

This week we’re going to look at what I am going to call ‘point defenses’ – permanent fortifications that don’t exist as part of a larger fortification system, but which are instead designed to protect a single point, like walled cities or castles (fortified private residences). Now I want to promise here at the beginning: we are actually going to get to the defensive structures and the ‘cool’ stuff like towers and gates and walls and ditches and so on. But first we’re going to have to lay some conceptual groundwork about what exactly a castle is supposed to be doing in order to understand why these fortifications are designed in the way that they are.

Now this is, as you may well imagine, a really large topic and so this post is going to be little more than an overview, even given its impressive-looking read time. Really, if you want to study castles or walled cities in more depth, there really is no substitute to looking individually at examples from a given area and era, especially since most fortifications from this period – especially the larger and more impressive ones – tend to be sui generis to at least some degree. Still I hope that at least an overview will serve to set out some of the basics.

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Why Castle?

Frontier fortifications and army bases often make a degree of intuitive sense, either aimed at controlling crossings over an entire border or protecting a military force in the field. Point defenses1 like walled cities or castles (or defensive systems that don’t cover the entirety of a frontier) often make less sense to modern readers and students, invariably leading to the famous misquotation of George S. Patton that, “Fixed fortifications are a monument to the stupidity of man” – what he actually said was “This [the Maginot Line] is a first class case of man’s monument to stupidity,” a comment on a particular set of fortifications rather than a general statement about them and one, it must be noted, made in 1944, four years after those fortifications were taken so we also ought not credit Patton here with any great foresight.

As an aside, the purpose of the Maginot Line was to channel any attack at France through the Low Countries where it could be met head on with the flanks of the French defense anchored on the line to the right and the channel to the left. At this purpose, it succeeded; the failure was that the French army proceeded to lose the battle in the field. It was not the fixed fortifications, but the maneuvering field army which failed in its mission. One can argue that the French under-invested in that field army (though I’d argue the problem was as much doctrine than investment), but you can’t argue that the Maginot Line didn’t accomplish its goals – the problem is that those goals didn’t lead to victory.

So before we get into the design of point defenses, we should talk about what these are for. Generally, fixed point defenses of this sort in the pre-modern world are meant to control the countryside around them (which is where most of the production is). This is typically done through two mechanisms (and most of point defenses will perform both): first by housing the administrative center which organizes production in the surrounding agricultural hinterland (and thus can extract revenue from it) and second by creating a base for a raiding force which can at least effectively prohibit anyone else from efficiently extracting revenue or supplies from the countryside. Consequently if we imagine the extractive apparatus of power as a sort of canvas stretched over the countryside, these fortified administrative centers are the nails that hold that canvas in place; to take and hold the land, you must take and hold the forts.

Via Wikipedia, a part of the Bayeux Tapestry, depicting a campaign by William of Normandy against Conan II, the Duke of Brittany in 1064/5. Note how the campaign is represented as a series of besieges of castles (each represented with its own motte, discussed below).

In the former case, the fortified center contains three interlinked things: the local market (where the sale of agricultural goods and the purchase by farmers of non-agricultural goods can be taxed and controlled), a seat of government that wields some customary power to tax the countryside through either political or religious authority and finally the residences of the large landholders who own that land and thus collect rents on it (and all of these things might also come with significant amounts of moveable wealth and an interest in protecting that too). For a raiding force, the concentration of moveable property (money, valuables, stored agricultural goods) this creates a tempting target, while for a power attempting to conquer the region the settlement conveniently already contains all of the administrative apparatus they need to extract revenue out of the area; if they destroyed such a center, they’d end up having to recreate it just to administer the place effectively.

In the latter case, the presence of a fortified center with even a modest military force makes effective exploitation of the countryside for supplies or revenue by an opposing force almost impossible; it can thus deny the territory to an enemy since pre-industrial agrarian armies have to gather their food locally. We have actually already discussed this function of point defenses before: the presence of a potent raiding force (typically cavalry) within allows the defender to strike at either enemy supply lines (should the fortress by bypassed) or foraging operations (should the army stay in the area without laying siege) functionally forcing the attacker to lay siege and take the fortress in order to exploit the area or move past it.

In both cases, the great advantage of the point defense is that while it can, through its administration and raiding threat, ‘command’ the surrounding hinterland, the defender only needs to defend the core settlement to do that. Of course an attacker unable or unwilling to besiege the core settlement could content themselves with raiding the villages and farms outside of the walls, but such actions don’t accomplish the normal goal of offensive warfare (gaining control of and extracting revenue from the countryside) and peasants are, as we’ve noted, often canny survivors; brief raids tend to have ephemeral effects such that actually achieving lasting damage often requires sustained and substantial effort.2

All of which is to say that even from abstract strategic reasoning, focusing considerable resources on such fortifications is a wise response to the threat of raids or invasion, even before we consider the interests of the people actually living in the fortified point (or close enough to flee to it) who might well place a higher premium on their own safety (and their own stuff!) than an abstract strategic planner would. The only real exception to this were situations when a polity was so powerful that it could be confident in its ability to nearly always win pitched battles and so prohibit any potential enemy from getting to the point of laying siege in the first place. Such periods of dominance are themselves remarkably rare. The Romans might be said to have maintained that level of dominance for a while, but as we’ve seen they didn’t abandon fortifications either.3

So fortifying key centers makes sense. How do you do it? We should start with castles because, we ‘ll see, things are easier when the position being defended is small.

Long on Rooks, Short on Pawns

While fortifications obviously had existed a long time, when we talk about castles, what we really mean is a kind of fortified private residence which also served as a military base. This form of fortification really only becomes prominent (as distinct from older walled towns and cities) in 9th century, in part because the collapse of central authority (due in turn to the fragmentation of the Carolingian Empire) led to local notables fortifying their private residences. This process was, unsurprisingly, particularly rapid and pronounced in the borderlands of the various Carolingian splinter kingdoms (where there were peer threats from the other splinters) and in areas substantially exposed to Scandinavian (read: Viking) raiding. And so functionally, a castle is a fortified house, though of course large castles could encompass many other functions. In particular, the breakdown of central authority meant that these local aristocrats also represented much of the local government and administration, which they ran not through a civil bureaucracy but through their own households and so in consequence their house (broadly construed) was also the local administrative center.4

Now, we can engage here in a bit of a relatable thought experiment: how extensively do your fortify your house (or apartment)? I’ll bet the answer is actually not ‘none’ – chances are your front door locks and your windows are designed to be difficult to open from the outside. But how extensive those protections are vary by a number of factors: homes in high crime areas might be made more resistant (multiple deadbolts, solid exterior doors rather than fancy glass-pane doors, possibly even barred windows at ground level). Lots of neighbors can lower the level of threat for a break-in, as can raw obscurity (as in a house well out into the country). Houses with lots of very valuable things in them might invest in fancy security systems, or at least thief deterring signs announcing fancy security systems. And of course the owner’s ability to actually afford more security is a factor. In short, home defenses respond to local conditions aiming not for absolute security, but for a balance of security and cost: in safe places, home owners ‘consume’ that security by investing less heavily in it, while homeowners who feel less safety invest more in achieving that balance, in as much as their resources allow. And so the amount of security for a house is not a universal standard but a complicated function of the local danger, the resources available and the individual home owner’s risk tolerance. Crucially, almost no one aims for absolute home security.

And I go through this thought process because in their own way the same concerns dictate how castles – or indeed, any fortification – is constructed, albeit of course a fortified house that aims to hold off small armies rather than thieves is going to have quite a bit more in the way of defenses than your average house. No fortification is ever designed to be absolutely impenetrable (or perhaps most correctly put, no wise fortress designer ever aims at absolute impenetrability; surely some foolish ones have tried). This is a fundamental mistake in assessing fortifications that gets made very often: concluding that because no fortification can be built to withstand every assault, that fortification itself is useless; but withstanding every assault is not the goal. The goal is not to absolutely prohibit every attack but merely to raise the cost of an attack above either a potential enemy’s willingness to invest (so they don’t bother) or above their ability to afford (so the attack is attempted and fails) and because all of this is very expensive the aim is often a sort of minimum acceptable margin of security against an ‘expected threat‘ (which might, mind you, still be a lot of security, especially if the ‘expected threat’ is very high). This is true of the castle itself, if for no other reason than that resources are scarce and there are always other concerns competing for them, but also for every component of its defenses: individual towers, gates and walls are not designed to be impenetrable, merely difficult enough.

This is particularly true in castle design because the individuals building these castles often faced fairly sharp limitations in the resources at their disposal. Castles as a style of fortification emerge in a context of political fragmentation, in particular the collapse of the Carolingian Empire, which left even the notional large kingdoms (like the kingdom of France) internally fragmented. Castles were largely being built not by kings but by counts and dukes who held substantial landholdings but nothing like the resources of Charlemagne or Louis the Pious, much less the Romans or Assyrians. Moreover, the long economic and demographic upswing of the Middle Ages was only just beginning to gain momentum; the great cities of the Roman world had shrunk away and the total level of economic production declined, so the sum resources available to these rulers were lower. Finally, the loss of the late Roman bureaucracy (replaced by these fragmented realms running on an economic system best termed ‘manorialism’) meant that the political authorities (the nobility) often couldn’t even get a hold of a very large portion of the available economic production they did have.5 Consequently, castle construction is all about producing what security you can with as little labor, money and resources as possible (this is always true of any fortification, mind you, merely that in this period the resource constraints are much tighter).

A wonderful map of political fragmentation in the Kingdom of France, made by Gabe Moss. Note that each of these colored zones (indicating a major vassal) would have been further subdivided (so the Duke of Aquitaine would have his own vassals just like the King of France). The actual holdings of the French kings are the small areas labeled “Royal Lands of Hugh Capet.”

Knight Takes Rook

Of course in this context the expected threat is going to shape the calculation of what margin of security is acceptable, which brings us back to our besieger’s playbook. You may recall when we looked at the Assyrian siege toolkit, that many of the most effective techniques assumed a large, well-coordinated army which could dispose of a lot of labor (from the soldiers) on many different projects at once while also having enough troops ready to fight to keep the enemy bottled up and enough logistic support to keep the army in the field for however long all of that took. In short, this is a playbook that strong, well-organized states (with strong, well-organized armies) are going to excel at. But, as we’ve just noted, the castle emerges in the context of fragmentation which produces a lot of little polities (it would be premature to call them states) with generally quite limited administrative and military capacity; the ‘big army’ siege playbook which demands a lot of coordination, labor and expertise is, for the most part, out of reach.

Clifford Rogers has already laid out a pretty lay-person accessible account of the medieval siege playbook (in Soldiers’ Lives Through History: The Middle Ages (2007), 111-143; the book is pricey, so consider your local library), so I won’t re-invent the wheel here but merely note some general features. Rogers distinguishes between hasty assaults using mostly ladders launched as soon as possible as a gamble with a small number of troops to try to avoid a long siege, and deliberate assaults made after considerable preparation, often using towers, sapping, moveable shelters designed to resist arrow fire and possibly even catapults. We’ve already discussed hasty assaults here, so let’s focus on deliberate assaults.

While sapping (tunneling under and collapsing fortifications) remained in use, apart from filling in ditches, the mole-and-ramp style assaults of the ancient world are far less common, precisely because most armies (due to the aforementioned fragmentation combined with the increasing importance in warfare of a fairly small mounted elite) lacked both the organizational capacity and the raw numbers to do them. The nature of these armies as retinues of retinues also made coordination between army elements difficult. The Siege of Antioch (1097-8) by the First Crusade is instructive; though the siege lasted nine months, the crusaders struggled to even effectively blockade the city until a shipment of siege materials (lumber, mostly) arrived in March of 1098 (five months after the beginning of the siege). Meanwhile, coordinating so that part of the army guarded the exits of the city (to prevent raids by the garrison) while the other part of the army foraged supplies had proved mostly too difficult, leading to bitter supply shortages among the crusaders. Even with materials delivered to them, the crusaders used them to build a pair of fortified towers blocking exits from the city, rather than the sort of elaborate sapping and ramps; the city was taken not by assault but by treachery – a very common outcome to a siege! – when Bohemond of Taranto bribed a guard within the city to let the crusaders sneak a small force in. All of this despite the fact that the crusader army was uncommonly large by medieval European standards, numbering perhaps 45,000.

Crucially, in both hasty and deliberate assaults, the emphasis for the small army toolkit tends to be on escalade (going over the walls) using ladders or moveable wooden towers, rather than the complex systems of earthworks favored by the ‘big army’ siege system or breaching – a task which medieval (or ancient!) artillery was generally not capable of. The latter, of course, is a much more certain method of assault – give a Roman army a few months and almost any fortress could be taken with near certainty – but it was a much more demanding method in terms of the required labor and coordination. Thwarting escalade is mostly a question of the height of defenses (because a taller wall requires a taller ladder, tower or ramp) and good fields of fire for the defenders (particularly the ability to fire at attackers directly up against the wall, since that’s where the ladders are likely to be).

The face of the threat: Escalade.

The other major threat to castle walls (apart from the ever-present threat of sapping) was catapults, but I want to deal with those next time for reasons that I suspect will make sense then. For now it is worth simply noting that catapults, even the mighty trebuchets of the 14th century were generally used to degrade defenses (smashing towers, destroying crenellation, damaging gatehouses) rather than to produce breaches. They could in some cases do that, but only with tremendous effort and a lot of time (and sometimes not even then). Consequently, for most castles the greatest threat remained escalade, followed by treachery or starvation, followed by sapping, followed by artillery.

A King In His Castle

The earliest castle designs we see in Europe during the Middle Ages are wooden ‘motte and bailey’ castles which emerge first during the 10th century and make their way to Britain after 1066. In the initial basic form, the core structure (the ‘keep,’ which is typically the fortified house itself) is placed on a motte, a hill (usually artificial) with a flattened top. The keep itself is constructed as a tall, wooden tower, with the height offering advantages both as a fighting position and for observation of the surrounding area. The motte is then enclosed by a wooden palisade (often two, one at the base of the motte and another at the crest) and surrounded by a ditch (the moat, which would be filled with water if it could be connected to a river or stream, but could also be left ‘dry’ and still serve its purpose), the dirt of which was used to build up the motte in the first place.

Via Wikipedia, another part of the Bayeux Tapestry showing the construction of a motte prior to the Battle of Hastings, 1066.

But as noted, the personal manor home of a significant noble (the rank in this case is often a ‘castellan,’6 literally the keeper of a castle, so entrusted by one of the more powerful nobles who holds sway over a larger territory; the castellan has the job of holding the castle and administering the countryside around it) is also an administrative center, managing the extraction of agricultural surplus from the countryside and also a military base, housing the physical infrastructure for that noble’s retinue, which again is the fundamental building block of larger armies. Which means that it is going to need more structures to house those functions: stables for horses, storehouses for food, possibly food processing facilities (bakeries, mills) and living space both for retainers (be they administrators or military retainers) and for the small army of servants such a household expects. Those structures (to the degree they can’t exist in the keep) are put in the bailey, a wider enclosed part of the settlement constructed at the base of the motte. As with the motte, the bailey is typically enclosed only by a wooden palisade; naturally that means the most valuable things (the physical treasury, the lord’s family) go in the keep on the motte, while the more space-demanding but less valuable things go in the bailey. There is a lot of room for variation in this basic type, but for now the simple version will serve.

The resulting fortification seems almost paradoxically vulnerable. The bailey, after all, is protected only by a ditch and a wooden palisade which a determined work-party could breach with just iron axes and an afternoon to kill. The core defensive motte with its keep adds perhaps only one more palisade and a steep climb. But in fact, these relatively modest defenses have greatly increased the cost of attacking this settlement. The motte and bailey castle, at least in its early wooden form, won’t stand up to a determined assault by a large and well-coordinated enemy, but that isn’t its purpose. Instead, the purpose of the motte and bailey castle is to raise the cost of an assault such that a potential opponent must bring a significant force and make a careful, well-planned assault; this the motte and bailey accomplishes quite well, which explains the long durability of the basic design, with stone versions of the motte and bailey persisting into the 15th century.

The quick mounted raid is now impossible; precisely because it will take a solid afternoon to breach the defenses, there is little hope of surprising the defenders. At the same time, the ditches will make any such work party vulnerable to missile fire (arrows, yes, but also javelins or just large rocks) from the palisade. And most of all, taking the place now demands you coordinate a work party, with some of your attackers splitting up to suppress the defenders, some making sure to block the exits so the defenders don’t rush out and attack your work party directly, and still more of your attackers in the work party itself. These very basic defenses have suddenly taken you from a position where a bit of surprise and rough numerical parity was enough to contemplate an assault to a position where you need several times as many attackers (for each of those divisions needs to be large enough to confidently win against the defenders if assailed).

Perhaps most importantly, the basic structure of this defense demands that you do this multiple times in sequence. We’ve already discussed the value of defense-in-depth, but in brief, every attack is at its strongest in the moment after it jumps off: everyone is alive, in the right positions, at the right time, coordinated and at least in theory clear on their objectives. Every movement and action beyond this point diminishes the power of the effort as coordination breaks down, attackers are killed and things break; this is what Clausewitz terms (drink!) friction – the unpredictable interaction of probabilities takes their toll on any plan, no matter how carefully designed. This is, by the by, more true in real warfare, where coordination is limited by communications technology, than it is in film or video games, where armies appear to mostly communicate by some form of instantaneous telepathy (it is amazing just how many clever sounding movie or game assault plans fall apart once you imagine trying to coordinate them with nothing more than shouting, or even a radio). As more and more things turn out unexpectedly or have to be improvised, the plan slowly shakes apart until eventually all of the momentum is lost.

Via Wikipedia, a model of York Castle as it stood in the 14th century, by which point the wooden structures of the motte and bailey castle had been rebuilt in stone. Nevertheless, you can see the layout of the bailey (foreground) and the keep on its motte (background). Note that the heavy use of prjecting towers is a later innovation; the wooden circuits of early motte and bailey castles generally lacked any kind of projecting towers.

The basic structure of a motte and bailey castle exploits this feature of warfare, forcing an attacker to overcome a series of obstacles in sequence, all while in contact with the enemy. Recall that this is a defense which really doesn’t envisage enemy artillery (because armies with lots of effective siege artillery were not common in the often small-scale warfare of the period; that’s not to say they didn’t exist, but if your motte and bailey castle forces the enemy to only attack with a big, expensive army that can build catapults, it has done its job, not the least because most possible enemies won’t have that capability at all), so an attacker is going to have to breach each layer in sequence while in contact with the defense and to pierce them all more or less ‘in one go.’ Consequently, taking the castle by storm means crossing (and probably filling in) at least one deep ditch, breaching a palisade under fire, then moving up a steep hill under fire, then breaching another palisade, at the end of all of which, the attacker must arrive at the keep with enough force and cohesion to take it. All of that is going to take a substantial attack and a lot of coordination and most potential attackers, the defender may hope, will lack either the resources or the determination to go through so much effort, especially as they are likely to have to do it multiple times: being entirely wooden, motte and bailey castles were fairly cheap and so a large territory could have quite a lot of them (note above on the Bayeux Tapestry how William has to take several such castles in order to capture Conan II of Britanny). Each motte and bailey castle thus raises the cost of trying to seize control of the territory; collectively they make that cost prohibitive.

Via Wikipedia, an artist’s reconstruction of 15th century York, showing York Castle’s classic motte and bailey design in the center, though built in stone. You can see how York Castle, functioning here as the citadel of a larger city defense system (see below), utilizes defense in depth: attackers have to cut through multiple layers of defenses before even beginning an assault on the castle proper.

Of course our principle of ‘antagonistic co-evolution’ is not done and the vulnerabilities of a wooden motte and bailey castle are fairly clear and easy to exploit. For one, the wooden palisade is mostly a blocking element, rather than a fighting position; attackers that reach the wall can actually use it as cover while tearing it down or setting it on fire. The entire setup, being made of wood, is vulnerable to fire but also to any kind of even-quite-modest catapult. And quite naturally, any military leader (which is to say, the military aristocracy which was emerging at the very same time as these castles) is going to want to build the kind of capabilities which will allow for successful castle assaults because, as we’ve already noted, castles function more or less as the ‘nails’ on the map which hold down the canvas of revenue extraction and military power.

Which in turn means evolving castle design to resist the methods by which a motte and bailey castle might fall. The most immediate change is in building material: wooden walls can only be so high, so thick and so resistant to fire. Stone, though far more expensive, offers advantages on all three fronts. And so, already in the late 10th century, we start to see stone keeps and gatehouses (supporting still wooden palisades); full stone castles would soon follow.

As an aside, one solution to this problem which doesn’t much appear in the Middle Ages but was very well-used in Iron Age Europe was what the Romans called the murus Gallicus, a hybrid wood-and-stone wall system. Gallic hillforts (called oppida) were built on hills, as the name suggests; their outer walls could be built by using earth fill to construct what was essentially a retaining wall, faced in stone, with transverse reinforcing wood beams every few feet. That created, in turn, a vertical stone surface, supported by the hillside itself, on which could be additionally built a wooden palisade for added height. The result was a very formidable fortification, assuming one had the hill to work with initially. You couldn’t knock it over or really undermine it effectively and the stone face was nearly vertical; the height of the hill meant that effective escalade meant coming up with a mole, tower or ladder taller than the hill (a thing, naturally, that the Romans ended up doing). That this style of fortification didn’t really reemerge in the Middle Ages speaks to the degree of path dependence in fortification design. Because fortification design tends to be evolutionary, it is possible in similar conditions to get very different responses as different designers try to meet the same threats by modifying different preexisting systems of fortification. That said, we’ll see next time something rather a lot like the murus Gallicus emerge to deal with the problem of gunpowder; the construction of Japanese castles (shiro/jo) also share many of the same principles.

Via Wikipedia, a model reconstruction of part of the murus Gallicus wall of Bibracte, showing what the construction of such a defense might look like. These walls could be quite a lot higher than this implies though, often taking advantage of natural hillsides.

Rook’s Defense

As we move to stone construction and especially full stone construction (which we’ll define as the point when at least one complete curtain wall – don’t worry, we’ll define that in a second – is in stone) in the 12th century, we’re beginning to contemplate a different kind of defense. The wooden motte and bailey, as we’ve seen, mostly served to resist both raids and ‘hasty’ assaults, thus forcing less coordinated or numerous attackers to set in to starve the castle out or go home. But stone walls are a much larger investment in time and resources; they also require a fair bit more careful design in order to be structurally sound. For all of that expense, the builder wants quite a bit of a security, and in the design of stone castles it is hard not to noticing increasing attention towards resisting a deliberate assault; stone castles of the 12th century and beyond are increasingly being designed to stand up to the best that the ‘small army’ playbook can throw at them. Of course it is no accident that this is coming at the same time that medieval European population and wealth is beginning to increase more rapidly, leaving political authorities (read: the high nobility) with both the resources for impressive new castles (although generally the number of castles falls during this period – fewer, stronger castles) and at the same time with more resources to invest in the expertise of siegecraft (meaning that an attacker is more likely to have fancy tools like towers, catapults and better coordination to use them).

Via Wikipedia, Krak des Chevaliers, one of the largest and most impressive castles built during the Middle Ages, located in Syria above the village of al-Husn in the Homs Governorate. It is not an accident that some of the most impressive castles are located in the Levant; the crusades brought Western European armies into contact with Byzantine and Islamic armies that still had access to meaningful chunks of the ‘big army’ siege playbook (as the fragmentation and deurbanization of the early Middle Ages was less pronounced in the East). Much of the revolution in castle design happening in the 11th-13th century seems to be directly attributable to European adoption of defensive design from the Near East.
I should also note this particular castle was substantially damaged during the Syrian Civil War; this picture was taken in 2002. The structure still stands, but the chapel and some of the interior has been damaged.

To talk about how these designs work, we need to clear some terminology. The (typically thin) wall that runs the circuit of the castle and encloses the bailey is called a ‘curtain wall.‘ In stone castles, there may be multiple curtain walls, arranged concentrically (a design that seems to emerge in the Near East and makes its way to Europe in the 13th century via the crusades); the outermost complete circuit (the primary wall, as it were) is called the enceinte. Increasingly, the keep in stone castles is moved into the bailey (that is, it sits at the center of the castle rather than off to one side), although of course stone versions of motte and bailey designs exist. In some castle design systems, with stone the keep itself drops away, since the stone walls and towers often provided themselves enough space to house the necessary peacetime functions; in Germany there often was no keep (that is, no core structure that contained the core of the fortified house), but there often was a bergfriede, a smaller but still tall ‘fighting tower’ to serve the tactical role of the keep (an elevated, core position of last-resort in a defense-in-depth arrangement) without the peacetime role.

While the wooden palisade curtain walls of earlier motte and bailey castles often lacked many defensive features (though sometimes you’d have towers and gatehouses to provide fighting positions around the gates), stone castles tend to have lots of projecting towers which stick out from the curtain wall. The value of projecting towers is that soldiers up on those towers have clear lines of fire7 running down the walls, allowing them to target enemies at the base of the curtain wall (the term for this sort of fire is ‘enfilade’ fire – when you are being hit in the side). Clearly what is being envisaged here is the ability to engage enemies doing things like undermining the base of walls or setting up ladders or other scaling devices.

Via Wikipedia, the layout of Beaumaris Castle. Begin in 1295 and never fully completed, Beaumaris represents a fairly advanced form of this design, with two concentric walls, a thin outer wall and a thick inner wall. Notice how all of the towers project, with arrow slits parallel to the walls so that defenders can fire effectively down the length of the wall at enemies sheltering at the wall’s foot.

The curtain walls themselves also become fighting positions. Whether on a tower or on the wall itself, the term for the fighting position at the top is a ‘battlement.’ Battlements often have a jagged ‘tooth’ pattern of gaps to provide firing positions; the term for the overall system is crenellation; the areas which have stone are merlons, while the gaps to fire through are crenals. The walkway behind both atop the wall is the chemin de ronde, allure or ‘wall-walk.’ One problem with using the walls themselves as fighting positions is that it is very hard to engage enemies directly beneath the wall or along it without leaning out beyond the protection of the wall and exposing yourself to enemy fire. The older solution to this were wooden, shed-like projections from the wall called ‘hoarding;’ these were temporary, built when a siege was expected. During the crusades, European armies encountered Near Eastern fortification design which instead used stone overhangs (with the merlons on the outside) with gaps through which one might fire (or just drop things) directly down at the base of the wall; these are called machicolations and were swiftly adopted to replace hoardings, since machicolations were safer from both literal fire (wood burns, stone does not) and catapult fire, and also permanent. All of this work on the walls and the towers is designed to allow a small number of defenders to exchange fire effectively with a large number of attackers, and in so doing to keep those attackers from being able to ‘set up shop’ beneath the walls.

Via Wikipedia, a modern reconstruction of a hoarding.

Because it will matter next time, it is worth noting something about the amount of fire being developed by these projecting towers: the goal is to prevent the enemy operating safely at the wall’s base, not to prohibit approaches to the wall. These defenses simply aren’t designed to support that much fire, which makes sense: castle garrisons were generally quite small, often dozens or a few hundred men. While Hollywood loves sieges where all of the walls of the castle are lined with soldiers multiple ranks deep, more often the problem for the defender was having enough soldiers just to watch the whole perimeter around the clock (recall the above example at Antioch: Bohemond only needs one traitor to access Antioch because one of its defensive towers was regularly defended by only one guy at night). It is actually not hard to see that merely by looking at the battlements: notice in the images here so far often how spaced out the merlons of the crenellation are. The idea here isn’t maximizing fire for a given length of wall but protecting a relatively small number of combatants on the wall. As we’ll see, that is a significant design choice: castle design assumes the enemy will reach the walls and aims to prevent escalade once they are there; later in this series we’ll see defenses designed to prohibit effective approach itself.

Via Wikipedia, 15th century machicolations on Craigmillar Castle in Scotland, viewed from below; these permanent stone elements, adopted from Near Eastern fortifications, replaced earlier wooden hoarding.

As with the simpler motte and bailey, stone castles often employ a system of defense in depth to raise the cost of an attack. At minimum, generally, that system consists of a moat (either wet or dry), the main curtain walls (with their towers and gatehouses) and then a central keep. Larger castles, especially in the 13th century and beyond, adopting cues from castle design in the Levant (via the crusades) employed multiple concentric rings of walls. Generally these were set up so that the central ring was taller, either by dint of terrain (as with a castle set on a hill) or by building taller walls, than the outer ring. The idea here seems not to be stacking fire on approaching enemies, but ensuring that the inner ring could dominate the outer ring if the latter fell to attackers; defenders could fire down on attackers who would lack cover (since the merlons of the outer ring would face the other way). As an aside, the concern to be firing down is less about the energy imparted by a falling arrow (though this is more meaningful with javelins or thrown rocks) and more about a firing position that denies enemies cover by shooting down at them (think about attackers, for instance, crossing a dry moat – if your wall is the right height and the edges of the moat are carefully angled, you can set up a situation where the ditch never actually offers the attackers any usable cover, but you need to be high up to do it!).

Speaking of the moat, this is a common defensive element (essentially just a big ditch!) which often gets left out of pop culture depictions of castles and siege warfare, but it accomplishes so many things at such a low cost premium. Even assuming the moat is ‘dry!’ For attackers on foot (say, with ladders) looking to approach the wall, the moat is an obstacle that slows them down without potentially providing any additional cover (it is also likely to disorder an attack). For sappers (attackers looking to tunnel under the walls and then collapse the tunnel to generate a breach), the depth of the ditch forces them to dig deeper, which in turn raises the demands in both labor and engineering to dig their tunnel. For any attack with siege engines (towers, rams, or covered protective housings made so that the wall can be approached safely), the moat is an obstruction that has to be filled in before those engines can move forward – a task which in turn broadcasts the intended route well in advance, giving the defenders a lot of time to prepare.

Well-built stone castles of this sort were stunningly resistant to assault, even with relatively small garrisons (dozens or a few hundred, not thousands). That said, building them was very expensive; maintaining them wasn’t cheap either. For both castles and fortified cities, one ubiquitous element in warfare of the period (and in the ancient period too, by the by) was the rush when war was in the offing to repair castle and town walls, dig out the moat and to clear buildings that during peace had been built int he firing lines of the castle or city walls.

Speaking of which…

Rook’s Pawn

The main difference in defending a town rather than a single fortified private residence is the area that needs to be defended: the town core is naturally much larger than the size of a single keep or bailey and so the circuit of walls surrounding it also needs to be much longer. That longer circuit, of course, means a higher cost in terms of constructing and maintaining the defense, but the advantage a town often has here is its own residents: the populace of a town often has a fair bit more labor to devote to defense construction compared to the medieval aristocracy who mostly draw their power and resources from the more thinly populated rural countryside.

Nevertheless, the larger size of the area being defended makes it harder to deploy concentric defense-in-depth solutions. There are also transit considerations: towns are, after all, economic centers, typically sitting at the junction points of many different local and regional routes, which means they tend to need lots of entry-points to facilitate all of that travel and trade and in turn that means lots of potentially vulnerable gatehouses. Meanwhile, internally, the desire for residents to move around the town freely and general land-use considerations make subdividing towns into walled districts (very common in video-games for memory-management and loading reasons) very difficult and as a result very rare. You can see this, for instance, looking back at the period city-maps from the Lonely Cities series: a good number of cities have either a citadel or a section of the town which is walled but also outside of the main circuit (often separated by a river), but full concentric styles of defense or multiple cell-like walled districts don’t really occur. There are exceptions, but they are relatively rare: most cities have a single primary circuit of walls, which, if they are breached generally give access to the main area of the town.

In Europe, the most complete and formidable set of city walls were without question the Theodosian Walls built to defend Constantinople during the reign of Theodosius II (r. 402-450). The Theodosian Walls stood for the whole Middle Ages but they really reflect the culmination of the ancient system of city wall fortifications, the ultimate answer to the kind of ‘big army’ playbook the Assyrians (and Romans) employed. So I want to both talk about the defense system but also note points where its method diverges from the walls of later medieval towns.

Byzantine Constantinople-en.png
Via Wikipedia, a map of Constantinople showing the circuit of the Theodosian Walls running along the western (left-hand-side) edge of the city. Needless to say, they defended an area far larger than any castle.

The Theodosian Walls had to cover some 5.7km and had nine gates; both numbers should immediately make clear that you needed quite a few people to man these defenses effectively. This was in particular a factor for town defense: most of the defenders are going to be citizens of the town called up to defend it in an emergency, rather than a standing guard. As far as I can tell, this seems to have made towns somewhat more vulnerable to surprise ‘hasty assaults,’ if the attacker could force a gate along a long circuit before the defenders knew where the attack was coming. Of course that problem is intensified by the fact that this is a single-point-of-failure system: the loss of one gate against a superior foe generally meant the loss of the town.

The Theodosian Walls are unusual in that they are a set of triple walls. The main fighting position was on the inner wall; in front of this was the peribolos, a low, flat, unobstructed gap, after which was the lower outer wall, a secondary forward fighting platform. The towers of the inner wall project out into the peribolos for exactly the same reason castle towers project: defenders on those towers can fire, unobstructed, down the peribolos, meaning that an attacker can find no safety here. The crenellation of the outer wall likewise only faced out, so attackers who seized the outer wall would have no cover from defenders fighting from the inner wall. Next, after another gap was a simple low forward wall, little more than a stone breastwork about 1.5m high. Finally, the low wall stood at the inner edge of a large moat, some 20m wide and 10m deep, because no good defensive system is complete without a ditch.

Via Wikipedia, a quite good diagram of the basic plan of the Theodosian triple-wall system.

That low wall is a kind of what we call an ‘outwork’ (we’ll see a lot more examples next time of forms of outworks). This particular kind of outwork is a product of the ancient world and uncommon in medieval fortifications to my knowledge; it was a response to the increasing use of torsion catapults during the Hellenistic period. While it did offer a position for defenders to use to sally out (for instance to destroy enemy siege engines), the primary purpose was to prevent enemy catapults from being able to direct fire at the base of the main wall and its towers. Even if knocked down, such an outwall’s rubble would obstruct direct fire on the curtain wall or the towers. This idea – using an outwork to physically block lines of fire on the curtain wall – is going to come back a bit later.

Paris, 1572, from from Georg Braun’s Civitates orbis terrarum (1572-1617). Image via the Historic Cities Research Project. You can see the outer wall, along with the remains of the city’s older inner wall. The main defense system is still only a single circuit, although this is reinforced to the left by a moat.

In contrast, most later medieval town wall circuits generally only have a single curtain wall, supported by a moat. As with castles, the wall is supported by projecting towers which can direct fire along its length and hardened gatehouses. Where cities sometimes do employ defense-in-depth it is with a ‘citadel’ – a hardened fallback position either inside the city or (more often) built in to the wall circuit; essentially a complete castle built into the city wall. The role of the citadel is important for thinking about what these defenses are intended to achieve: defenders who have lost the main area of the city but have held out in the citadel are unlikely to be in a position to recapture the city or even to seriously threaten to do so. But the citadel has important negotiating power. Even a small number of surviving defenders can likely hold a citadel (with its stockpile of supplies) for a long time; taking such a citadel by storm poses all of the problems of storming a castle, with the added disadvantage of having to do so through city streets. Consequently, defenders holed up in the citadel are in a good position to negotiate for terms: perhaps being able to march out unharmed in exchange for turning over the citadel, or else negotiation less onerous terms for the city in general (alternately, they might try to hold out until a friendly relief army could arrive).

Exeter, 1617 from Georg Braun’s Civitates orbis terrarum (1572-1617). Image via the Historic Cities Research Project. Here you can see a pretty clear example of a citadel in the upper left corner.

And that brings the focus to something important about almost all medieval siegecraft: the siege and negotiations generally proceeded side-by-side. By raising the cost of a siege (either a blockade or a storming assault), the defender could improve their bargaining position, even if they were always going to have to surrender. Meanwhile the attacker, by very visibly preparing for a deliberate assault could signal to the defenders their resole and thus attempt to encourage surrender. As far as I can tell, far more fortified medieval towns and castles surrendered than were ever taken by storm and so consequently a lot of this fortification work is as much about shifting bargaining positions in the event of an attack as it is resisting an attack.

Next time, we’re going to move a bit forward and look at the impacts of artillery, both catapults and more importantly gunpowder on this system and in particular at a new system of European fortifications which emerges to deal with gunpowder armies.

  1. I struggled for a good term for ‘defenses designed to protect a single settlement and settled on ‘point defense’ in its most general possible meaning as encompassing the point reasonably well. Of course point defense can mean something rather different in a modern, technical concept, although the definitions are linked.
  2. That said, strategies of raiding and devastation were common in the Middle Ages in the small-scale warfare between nobles and sometimes even in the larger scale warfare between kingdoms. If your goal is merely to weaken your enemy, you don’t need to take the castle – you can inflict enough damage on the countryside by raiding to deny your opponent income and thus degrade his ability to raise and supply his own armies. The high difficulty of taking castles is what makes this sort of strategy so attractive.
  3. The Romans are also really good at taking fortified settlements, to the point that effectively no fortification could be expected to stand against a determined Roman army. That really changes the calculus, but most medieval armies simply lacked the resources, size and coordination to match Roman siege engineering.
  4. By which we should understand ‘center for the extraction of the countryside’s agricultural surplus and then the spending of that surplus’ because that is essentially what ‘administration’ means in the pre-modern world
  5. Something that could, by the by, be good for your average farmer. In the pre-modern world, where there were strong limits to how far economic productivity could be increased, highly effective taxation systems might push the actual everyday farmers closer and closer to subsistence. The degree to which the loss of economic complexity through trade and urbanism could be balanced by reductions in effective taxation is something it looks like we’ll be discussing fairly soon, given the current balance of votes in the ACOUP Senate
  6. Or one of many such equivalents or near-equivalents. While games tends to present medieval titles as a single, coherent logical system, in practice there is a bewildering array of titles whose definitions shift from one area to the other and aren’t always even equivalent across systems.
  7. Just to be clear, the ‘fire’ we are discussing here is still muscle-powered, not chemically powered (that is, arrows and javelins, not muskets). Nevertheless, in military terminology, any weapon-system engaging at range is ‘fire’ (as compared to ‘shock’) and we’re going to stick with that terminology even when we are dealing with arms that do fire that aren’t firearms. Alas that modern military terminology was not designed for a pre-gunpowder context!

220 thoughts on “Collections: Fortification, Part III: Castling

  1. I suppose older histories use “missile” and “shot” (as translated) rather than “fire,” as in “we advanced to within bow shot of the walls,” or “the remnant were showered with missile weapons” and so on. “Fire” seems anachronistic when applied to pre-gunpowder weapons, even if in common usage.

  2. To keep up with the spirit of this blog’s title, one overly pedantic correction: in German, “die Bergfriede” is the plural form, the correct singular form would be “der Bergfried”.

  3. Interesting! One thing I have wondered ever since I read The Lonely City series is, how would rivers impact the fortification of cities? What kinds of defenses would cities install to stop an invading force from sailing into the city by river, while still keeping the water navigable for trade (for example the grain transport up the Tiber to Rome)?

    1. The norm was for the fortified city to be on one bank of the river, rather than have the river flow through the fortifications. That’s the case for example with London, Innsbruck, Nuremberg, Munich, Kufstein, Regensburg, Salzburg, Vienna. Also pretty clear in the picture Bret showed of 15th century York. Off the top of my head I can’t think of an obvious example of the opposite – maybe Paris?

      Of course it would also have been pretty common for signficant settlements to quickly grow up on the opposite bank, as in the case of London & Southwark, but those didn’t come to be regarded as part of the city proper until much later

      1. The Pegnitz pretty much bisects the Nuremberg old town, but it is not a river for large scale trading. The people of Nurmenberg thus chose to block river traffic by securing the points there the river passes the city walls with vertical bars

        1. That was a function of the city’s growth over the centuries; the Servian walls (and the pomerium) were all on the east bank; in fact even the Campus Martius (where the Pantheon stands) was outside. Aurelian had more inhabited real estate to protect – and still didn’t bother with Vatican Hill; it wasn’t fortified until after the Arabs sacked it in 846.

      2. The obvious examples would be Prague and Budapest, though in both cases those were separate settlements that grew together, IIRC. (and in the case of Prague, seems to have have lead to basically two separate defensive circuits, which is how the swedes in 1648 could capture the little side (by treachery/surprise) but be kept out of the part of the city on the other side of the river)

      3. Even Paris started off as the ‘Île de la Cité’ with all the important buildings and fortifications on the nice defensible island in the middle of the river. The suburbs on either bank were expendable, at least in the minds of the rulers.

    2. Constantinople, famously, had the access literally chained off – there was a huge chain stretching across the water. Otherwise not an example, since the river didn’t really run through the city, but it sure didn’t make things easier for attackers. I’m pretty confident this is where G.R.R. Martin cribbed the idea from for his Battle of Blackwater.

        1. They used them a lot in the Classical world to lock off access to fortified harbors as well. The chain towers also had cranes to swing over a drop stones (*) on the ships fowled up in the chains.

          * I recall right they were called dolphins because they conical and and shaped to pierce through a ship.

      1. > The Japanese castles stood up to the fierce military competition that took place in Japan during the 14th to 16th centuries.

        I know Japan was famous for fragmentation and wars, but I think it’s a bit like saying that Australia’s predators had fierce competition among them. Technically true. Yet when house cats arrived on European ships, they became a major problem for the local fauna such as bandicoots. There are now various projects to contain them, such as wire fences and trained labradors. China also had periods of chaos and warfare, and despite being often credited as the place where gunpowder (a.k.a. fire medicine) was invented, was soundly defeated and brutally humiliated by Europeans in Opium Wars. Or when Mongols arrived, they showed Europeans their place and completely new ways to wage war. Or when everyone was amazed by martial arts in the 80’s, but then UFC and MMA put them to test(they’re eclectic disciplines, but no single martial art dominates them except for maybe BJJ).

        My point is that when you play board games with the same group of friends, you’re prone to groupthink. I think Japan was quite isolated. If it wasn’t, it wouldn’t have such exotic and unique culture.

        No disagreement on the other parts – I simply didn’t read enough about that. But I agree there were examples of lower quality, cheaper equipment in Europe – such as black steel used by black cuiraissiers, or brigantines (often made from bits of older armor).

        1. Japan went through periods of isolation and periods of pretty extensive contact, it’s just that one of the longest periods of isolation happened just at an important historical break point.

          1. Japanese history shows a fascinating pattern of eras of wholesale borrowing from other cultures alternate with eras of isolation and assimilation of the ideas gobbled down.

        2. “When Mongols arrived, they showed Europeans their place and completely new ways to wage war”.

          Not entirely, they conquered several eastern European countries, but never broke into central or western Europe. In-fact they failed in the subjugation of Hungary twice, with the battle of Mohi being very close. Also castle doctrines were vindicated as the Mongols failed to capture a single stone Hungarian castle. The issue seems to be their is a belief in Mongol invincibility, even in wars they eventually lost and theoretical battles against enemies they never faced.

          1. I don’t think it’s worth it to be *entirely* correct at all times unless you’re writing a computer program. I knowingly made a simplification for the sake of clarity and brevity. My point was that it was a shock to medieval Europe and the ways most of it waged war. In the end, it was one of the examples I used to illustrate my larger point, namely that innovation in isolation is limited. Which I think happened to Japan. Digressions can be fun, and we have a threaded comment system, but I didn’t want people to lose the big picture from sight. It’s quite common for me to go over my reply and make it shorter.

    3. The fortifications will be a small wall/ palisade. An army could not gather boats for an invasion without being detected. The target was abvious and could be re-inforced immediately. The number of boats will be high, both for men and provisions. Seaborne invasions were carried because the destination was not apparent initially.
      So the threat was for an amphibious assault once the siege was already started. This was difficult because there will be no space for units to deploy, maneuver or offer supporting fire. The crusaders took great pains to move directly from ships to the seawall of Constantinopole without landing. This offered maneuver space and high platforms for suppresive fire.

    4. Or just a bridge might get you a pretty good firing position over any passing boat.

      And most city are pretty build in, so there isn’t that much landing opportunity inside the city proper. Giving the defender amples occasions to mount an effective defense.

      During the Scandinavian raid in medieval europe no city being stormed from the river come to my mind.
      On the other side invader tended to just port ship upstream in case of too difficult a siege.

      1. In fact, the Museum of London has a trove of Viking weapons recovered from the bed of the Thames near London Bridge, where defenders on the bridge apparently succeeded in sinking an attacking ship

    5. Take a close look at the map of Constantinople in the post. The writing is TINY!, but all along the coastal edge of the city you’ll see things labeled as “Gate” and that is because there was a real wall running the entire coastline, even sometimes through places that had been harbors. It also shows the chain running across the mouth of the Golden Horn, indicating a length of chain over half a kilometer!

  4. Stone must have been fabulously expensive to quarry and transport, brick was an intermediate solution, cheaper but not vulnerable to fire. We really need a series on stoneworking similar to the one you did on ironworking.

    1. Interesting point. Malbork is very much on my to-visit list – headquarters of the Teutonic Order and sometimes cited as the world’s largest brick building. Not much stone locally available on the Pomeranian mudflats

      1. You need at least 2 days to properly visit it, especially if you like to stop, think, and read all the plaques.

    2. I’m not sure about the relative cost of bricks to stone. However, at least in Britain the brick-making craft seems not to have returned to general usage after its loss in post-Roman times till perhaps as late as the 12th century. In castle building, brick was generally not considered as strong as stone, so very few brick castles were built in the heyday of castle building in England. Kirby Muxloe and Tattershall are both examples in England, but not till the 15th century was brick used in these. They’re considered more as fortified manors than as full-blown castles despite their names.

      1. I’m Dutch and obviously the river delta that is the Netherlands is also quite lacking in stone. Thus here the majority of castles (and churches, by the way) are made out of bricks. I think it is a tradeoff of the costs of transporting the stone vs. the costs of burning the mud, with burning mud turning out cheaper for this country but more expensive if you could get stone anywhere nearby.

        1. Of course cannon changed everything, when it was discovered that brick would absorb solid shot far better than stone. And as mentioned elsewhere, the introduction of coked coal meant you could fire the bricks very hot for a long time and get a better product.

        2. Don’t forget the Netherlands had major deposits of peat which could be extracted and transported at fairly low cost.

    3. Brick is – this might surprise you – very expensive, sometimes not less expensive than stone and stoneworking.

      The materials need for brickmaking is of course more common than stone, as you just need clay and mud. However, in order to make bricks, you need to *bake* them in a kiln/furnace, which could cost a huge amount of wood to do so. That along makes brickmaking very resource intensive – the timbers consumed in large-scale brickmaking wouldn’t be less than timbers consumed in large scale ironworking, and the latter could consume a small forest.

      Some IRL examples of these can be seen in China and Japan:

      Chinese dynasties tend to construct huge walled cities in Chinese plains where stone and quarries are scarce. Yet instead of relying on bricks, Chinese officials chose to use rammed earth, since ramming earth into a hardened mass was much more easier than baking things in an oven and then pile them up. The majority of Chinese city walls – including the Great Wall constructed in early Ming dynasty – have a massive “core” made out of rammed earth and only a thin “shell” of stone or baked bricks outside of them. The fuel cost of brick was another factor: Chinese plains have few forests as well, and Chinese officials would better use the few trees they have for ironworking (weapons and tools were much more important) rather than brickmaking.

      Pre-modern Japan didn’t even have a developed brickmaking technology to begin with, and overall pre-modern Japan had much less brick buildings than pre-modern China. Most of Japanese castles, as our host mentioned, were made out of stone and woods. Only after Meiji Restoration did the modern brickmaking technology being introduced to Japan, and it was being viewed as something very “western” and even “exotic” in the eyes of Japanese for a good while. When the Ginza Bricktown (they very first brick neighborhood in Japan) was completed in 1877, many Japanese rumored that living in brick buildings would kill them and therefore refused to move in.

      1. It wasn’t until the introduction of coking- baking coal in an airless oven to drive out most of the volatile content, leaving mostly carbon plus some ash- that the energy cost of kilning bricks was lowered enough to allow their ubiquitous use. Not to mention mass production of cast iron and, later, steel. And less obviously, distilled liquor: coke could be used for baking and other food-related uses because it was cleaner burning. Leading to Europe’s first “drug problem”: dirt cheap rotgut made more palatable by flavoring with juniper berries, hence “Gin Lane”

      2. It wasn’t until the introduction of coking- baking coal in an airless oven to drive out most of the volatile content, leaving mostly carbon plus some ash- that the energy cost of kilning bricks was lowered enough to allow their ubiquitous use. Not to mention mass production of cast iron and, later, steel. And less obviously, distilled liquor: coke could be used for baking and other food-related uses because it was cleaner burning. Leading to Europe’s first “drug problem”: dirt cheap rotgut made more palatable by flavoring with juniper berries, hence “Gin Lane”

        1. I must confess I really don’t know how the use of charcoal would ease distilling or baking. In the case of bricks and metals charcoal has obvious advantages, as you will get a much higher temperature in a charcoal fire, especially when you stoke it.

          In case of baking, I would like to point you to masonry owens, which have been very often wood-fired. Owning one, I can assure you that its operation with wood is fine, and the wood burns quite cleanly enough not to affect the taste of the food in an unpleasant manner, though of course, you only put the food inside after extinguishing most of the fire.

          The same goes for distillation of alcohol. It does not require a high temperature, so wood-fired stills work quite fine.

          In any case, the use of charcoal increases energy cost, not vice versa. Making charcoal out of wood takes energy, and is costly compared to simply burning wood.

          1. Raw coal is dirtier than wood or wood-derived charcoal. One citation that coking allowed it’s use in a food industry where it would otherwise not be usable is Nersesian, Roy L (2010). “Coal and the Industrial Revolution”. Energy for the 21st century (2 ed.). Armonk, NY: Sharpe. p. 98. ISBN 978-0-7656-2413-0.

          2. The Domestic Revolution: How the Introduction of Coal into Victorian Homes Changed Everything by Ruth Goodman

            Its subtitle is inaccurate: it was introduced as early as Elizabethan times. And a lot of the book revolves about the changes to cooking.

      3. Stories of people worrying over how new technology would lead to disastrous results are always entertaining. People being afraid that mass-market novels would destroy humanity’s intellectual capacity, or that passenger locomotives would drive people who looked out the window insane because of how fast the landscape outside is moving, that 5G would give people cancer, etc.

          1. Precisely; it *feels* that way. Parents are also very concerned about the internet ending critical thinking (nearly all peer-to-peer communication on the internet is criticism), and that excess device usage will lead to illiteracy (it is now more difficult than it has ever been for a child in the West to create a friendship if she or he is unable to communicate in text).

          2. People say that about literally every new communication technology, or at least every communication technology invented after the popularization of IQ testing. But similar remarks were made at least as far back as the invention of the printing press. Novels were the TikTok of the early modern period.

          3. Tut, tut, tut. Only as far back as the printing press?

            Don’t you know that literacy destroys memory? That’s why Socrates disapproved.

          4. “People say that about literally every new communication technology”

            Especially things liked by young women or teenage girls. Those new-fangled novels will rot your brain!

        1. And sometimes those people are right. Try searching for these terms. You may want to use image search.

          1. Uranium chocolate

          There was a time, shortly after the discovery of radioactivity, where they were sure it must be healthy. They were adding radioactive elements to all kinds of consumables, cosmetics, toothpaste… because obviously, energy is good! We used to have a mechanical clock with luminescent face, visible in the dark. Radium condoms by NUTEX (“That’s how they made lightsabers in the 1940’s”)

          2. Agent Orange, DDT

          3. Doctors recommending cigarettes

          4. Disposable plastic (“pacific plastic patch”)

          5. Sosnowsky’s hogweed, the toxic weed that has taken over Russia. Russian Federation already has a deficit of arable land. A natural plant was modified to spread quicker, because it’s very rich in nutrients.

          6. Antique Romans loved lead and would use it for things like wine vessels, water pipes, vats for cooking defrutum. And are we really smarter these days? Lead is used for hunting. Many times an animal is shot with lead, but survives, leading to slow lead poisoning. People eat that meat. Lead pellets are commonly used for hunting birds, and hunters drag their feet on replacing it. Ducks have a habit of swallowing stones from lake beds, which aids in their digestion. Lead, the powerful neurotoxin. It was in gasoline too.

          7. Coca-Cola was originally named after cocaine and cola nuts.

          8. Subprime mortgages

          9. Eternite, asbestos

          10. Palm oil (recent research suggests it promotes metastasis)

          11. Pop-up ads

          12. Clippy

          13. Mercury in thermometers

          My point is not “change bad”, but that critical thinking should apply to inventions too.

          1. Just to point out, those are more examples of “things we should have feared, but didn’t” (people thought all of those things were great), not “things we feared, but needn’t have”, like the post was talking about.

            In the camp of “things we feared, and rightly so”; maybe nuclear weapons? Not so much for the direct destruction they’ve caused so far (I feel pretty confident that conventional explosives have killed many more people), but for the fact that the average background radiation basically everywhere on Earth has gone up compared to a century ago due to the decades of open air testing.

          2. I’m amused that you name both things that have genuine danger that wasn’t appreciated at the time (radiation, lead, asbestos) and things which only pose dangers inherent to the thing’s design (pop-up ads, Clippy, arguably subprime mortgages).

          3. @GreatWyrmGold

            The other two things were there for humor, but subprime mortgages did cause a global financial crisis in 2008, didn’t they? The whole idea of interest when giving a loan to someone is because the bank wants to have profit but none of the responsibility, and no domain expertise and effort to figure out if your business failed due to your fault or you’re trying to cheat the bank. In fact, the responsibility is pushed so far the bank doesn’t care if you ARE conducting a business, only if you’re capable to pay. The alternative would be just splitting the profits at the end (inspired by David Graeber’s “Debt: the first 5000 years”).

          4. @Boruskates
            It wasn’t the subprime loans themselves (and lending money to people who do not already have tons of money is not any kind of innovation) that caused the 2007 crisis. Major lenders were bundling multiple subprime loans together and giving the bundle a sticker price that was more than the sum of its parts, but then a relatively small proportion of defaults in the bundle would lead to a bundle that could never fully pay off its price, and then the whole thing became “worthless” even though it was still overwhelmingly good debt from hardworking careful people who are mostly still today paying off that mortgage.
            The real crunch happened because the majors needed those bundles to retain their maximum value so they could use them as collateral for their own borrowing, borrowing the majors needed to cover all of the stock market gambling and other speculation they were doing.

      4. > However, in order to make bricks, you need to *bake* them in a kiln/furnace, which could cost a huge amount of wood to do so.

        You are right in all the relevant ways, but you can make bricks without fire, and they can be cheap.

        1. Adobe (dried bricks). They’re not as hard as baked bricks, and suitable mostly to arid climate because humidity turns them into mud.
        2. Dry pressed bricks (also known as compressed earth bricks). This is a modern technology and as such requires quite precise machining. Here’s a manually operated to produce bricks:

        1. Of course, dried mud bricks were a common building material in Mesopotamia and regions around it. However, as you said, their turning-back-into-mud-when-it-rains character made them an ill-suited building material in non-arid regions, which means the majority of the human-settled regions in the world. Even in Mesopotamia, a lot of ziggurats only use mud bricks inside, with a shell of baked or glazed bricks outside, to defend themselves from potential rains.

          This is also part of the reason why I brought up rammed earth (which can be understand as the precursor of dry pressed bricks you mentioned) in the previous post. Chinese plains mostly belong to Monsoon climate, so mud bricks would not stay long. Rammed earth, meanwhile, is far more resistant to rains, therefore making them cheap materials for good defensive works. A section of Shang dynasty rammed earth walls, built around 1500 BCE, still stands (!) in modern-day Zhengzhou.

          (Rammed earth walls are usually at least 3m thick, for instance the Beijing city walls are 8.6m thick at the bottom and 6.7m thick at the top. They are basically earthen dams, not unlike the glacises of later European fortifications, and could even withstand light artillery blasting – much more effective than mud brick walls.)

          1. Mud brick was a common building material in northern Europe and in India. It’s easy to rain-proof – add chopped straw and a binding agent (any vegetable oil) and a lime plaster as a final coat, wide eaves and a stone footing and it will stand through a monsoon – several if kept in repair.

  5. Great stuff, as usual, and reminds me that I must get around to visiting Beaumaris Castle one day (I’ve been saying that for 40 years …)

    As I understand it, Norman castles in England, and later in Wales, were also built to defend against uprisings from the conquered population – who presumably wouldn’t have access to catapults and the like.

    1. It’s my understanding that pretty much all castles had also the goal if protection against peasants rebellions, those weren’t exclusive to England. But the difference with army defence being that most of the time a palissade would be enough, so that goal was easily filled.

    2. I think a lot of that is baked into the castle’s role as administrative center- we’re not just talking about a lord and his (very few) bureaucrats, but also the armed force that enforces his rule. The small polities that build these castles don’t have the capacity to maintain something like a modern police force, and the dozens/hundreds of full-time soldiers in their employ would be incredibly vulnerable if dispersed. Even in places that aren’t recently conquered, conflict between rulers and ruled is a foreseeable hazard and the latter will always have numbers on their side, making a force-multiplier like a castle necessary.

    3. Sweden has an interesting perspective on this, in that castles seems to largely have been extensions of state power rather than constructed by the nobility on their own initiative, and while the games of politics largely revolved around being appointed castellan of various important castles. But then Sweden comes late to the castle-game, and they are never as extensive as on the continent. (something should probably also be mentioned of the coastal defence towers, and the militarized churches that belong to an earlier period and seems to largely have been intended to defend against baltic vikings)

  6. In the case of two of the most impressive castles I’ve visited, Conwy and Caernarfon, the extremely formidable castles are within, and serve as the citadel of, fortified towns. In both these cases, although there may have been pre-existing settlements, I get the impressions the towns were built along with the castles as a kind of logistical support / outwork – kind of overgrown baileys. I can’t find an online cite for this, but I recall reading and being surprised when I visited that Caernarfon – a big place – resisted a serious siege by the Welsh with a garrison of only a few dozen.

    Nuremberg and Salzburg also come to mind as cases where the town citadel is a serious castle in its own right, although in those cases I suspect there are layers of political complexity in play: both defending the city against outsiders, but probably equally importantly having a defensible seat of imperial/episcopal authority within the walls to keep uppity townspeople in check.

    1. I think market forces also play a role here- once the castle exists, people are likely to want to live near it, both for economic opportunity (the richest people in your area live in the castle) and safety (places near the castle are easiest to defend, and if that fails you might be able to take refuge inside the castle itself). So you’re likely to see castle towns growing over time even without deliberate government action to promote them.

      1. Castles as defensive points in a network are usually sited in places inconvenient for large settlement (on top of steep hills for instance). Castles as part of town defences – either to control the town or strengthen the defence – are at places that are already of commercial importance. Fortified towns (eg Warwick, Exeter, Hastings) do better at growth.

    2. Nuremberg Castle was politically two castles for a few centuries: the Imperial castle (kept by a castellan) and the Burgrave castle, standing side-by-side. The city, it seems, was very much on the side of the Emperor, got independence from the burgraves in the 13th century and became a free imperial city. In the early 15th century the bugraves sold their castle (burned down by then. It got re-build.)

  7. Nice picture of Krak. My dad visited it when he was younger; he said even seeing it from a distance it made him physically sick at the thought of having to try and get inside it while there were people inside trying to stop you.

    Which offers another perspective on some of the finer castles out there, especially in border/rebellious areas like Wales for England: a big stone castle is an incredible intimidating statement of power. in medieval Northern Europe most buildings were small by modern standards – with the only major outliers being cathedrals (awesome reminders of God’s power) and big castles (awesome reminders of the nobility’s/royalty’s power)

    1. Borders were so important that you got marcher Lords, margraves, and marquises. You outrank central Lords if you were an — edgelord.

  8. As we’re being pedantic here: “The earliest castle designs we see in Europe during the Middle Ages are wooden ‘motte and bailey’ castles which emerge first during the 10th century and make their way to Britain after 1066.”

    Although the Norman conquerors of Britain built many motte and bailey castles from the conquest onwards, there were a handful built during Edward the Confessor’s reign, as a result of influence from over the Channel, particularly in Herefordshire. See for example Richard’s Castle and Ewyas Harold Castle.

  9. One question I have is about the peasants being able to take shelter in the castle.

    When I was younger I was told that the local peasants could take shelter in the lord’s castle when needed, because protecting them was his duty. And they couldn’t pay any taxes if they were dead.

    Later I was told that this was nonsense, the lord wouldn’t want any extra people in the fortress eating limited food supplies. And who cares about peasants anyway?

    I am sure it varied from place to place and time to time, but what was the usual practice on this?

    1. The food availability would be about 1-2 weeks for the garrison plus peasants. So the peasants will gather inside during a raid (actually only a few will actually have time to move inside) and will be denied entrance during the advance of a big besiesing army.

      1. That really depends, remember the castles are administrative centres: Which means that taxes are collected there, and taxes often means foodstuffs. (everyone wants to get paid in coin, but you take what you can get) which means castles were often basically storage points for large amounts of food (either to be consumed directly by the people living there, by a peripateic monarch, or to be sent somewhere else)

    2. “Castle-guard’ was a common feudal obligation on the peasantry. Able-bodied men had to do periods of watch at the castle, in readiness for times of siege. Very few lords had a large enough retinue to defend a castle without such help. Towns had the same system – neighbourhoods were allotted sections of wall to defend. Obviously a castle cannot hold all the peasants, but it could take most of the nearby ones, much cattle and most of the more valuable items. Long sieges were rare – you can’t campaign until May and you want to be back home by late September, before the rain and cold destroys your force.

      That said, the last stronghold of the north British – Dumbarton Rock – fell to a combined Irish and Scandinavian force after a siege of two years. But the besiegers held the sea and could draw on Ireland for provisions.

    3. It depended on circumstances. If the besiegers tried to starve out the castle, extra mouths to feed would be a liability. But if they were unable to completely encircle the castle – for example to blockade the sea route, extra people were valuable as extra defenders. Maybe attackers counted on their ability to assault the castle, maybe they HAD to do it because they were working under a time pressure and knew a relief force was coming. Sometimes the besieged would appeal to the chivalrous side and ask the enemy for free passage of women and children (which was NOT always granted), so they would not get killed and would stop depleting the rations.

      I don’t remember the exact sieges, but I’m sure it was something on SandRhoman History channel (youtube). Many of the fortresses and fortified cities in Netherlands, especially star forts (early modern) were located at rivers or near shore.

  10. Great post as always. I should note that the Maginot Line’s failure was likely because it was overbuilt. The Germans NEVER intended to attack through areas defended by it, so the French arguably didn’t need to build so much (with fewer resources for the field army, especially its communications).

    1. That, and as our host mentions, poor communications and intelligence. Yes, the French assigned more and better trained and equipped troops to Belgium than defending the Maginot line, and the fortifications allowed this sort of allocation. But the Germans actually concentrated in Belgium even harder, with more percentage of their forces attacking than covering the far less defended Sigfried line than the French had defending the Maginot line.

      1. > But the Germans actually concentrated in Belgium even harder, with more percentage of their forces attacking than covering the far less defended Sigfried line than the French had defending the Maginot line.

        Yes, it seems to me the Germans were pretty sure the French will not counter-attack into Germany, leaving their fortifications, so they could leave only a token force opposing it.

        Overall a fortification makes the most sense if it blocks a far larger attacking force than the defending one.

        1. Certainly, when you expect to be outnumbered,* you don’t want to be in the position of building fortifications that will take more manpower to hold than the enemy bothers to plunk down opposing them.

          On the other hand, just making a territory inaccessible to the enemy so that you can ignore that sector of the front can have value, in that while you may still be parking more men there than the enemy does, you’re parking significantly less men than you’d need to without the fortifications.

          *(and just going by national populations, the German army in the West would predictably outnumber the French unless the Germans repeated WWI by fighting on both sides of their country at once)

          1. ” the Germans repeated WWI by fighting on both sides of their country at once”
            They (barely) managed to avoid that the second time around.
            For a while

        2. Well, this was the actual history for WW2. The French allocated 3rd rate troops for the defense of Maginot line and the Germans put 1st rate troops for its attack. It was a close gamble as the French reinforcements (artillery, Char 2 tanks and decent infantry) arrived only 8-12 hours too late. As Brett explained it was a success of tank and IFV speed vs train speed, not of offensive vs defence.

      2. My impression from contemporary witnesses is that the French were rather too invested in their impenetrable Maginot line. The trouble with static defenses is they’re static. The Allies at least were still in the WW I mindset which was all about a good defense and unprepared for the highly mobile tactics made possible by mechanized cavalry.

        1. Your term “mechanised cavalry” is a bit anachronistic, and applies Anglo-Saxon thinking to German army. The Germans still had cavalry units in WWII. Their armoured troops formed (and still form) their own branch, separate both from infantry and cavalry. Similarly, for Russians, the armoured troops are infantry.

          1. In Polish language it translates to “mechanized infantry”. In fact, for pedantic people there are two similar terms: MECHAnized infantry for infantry which uses the vehicles for fire support, and MOTOrized infantry for those who only use vehicles dragoon-style, for transport, but fight on foot. Central and Eastern Europe lacks natural borders, so mobility is a huge deal. Trucks would be for motorized infantry, APCs and IFVs such as the new borsuk – mechanized. The distincting is not widely known though.

          2. I’ve seen the difference between mechanized infantry (fights from and with their IFVs) vs motorized infantry (rides to the battlefield on vehicles, but fights on foot while their vehicles stay off the battlefield) used for NATO/American-style armies as well.

          3. “Armored Cavalry” is not even English-speaking thinking… it’s American thinking in particular.

            The British had a somewhat different doctrine in the 1940s, which divided tanks into “infantry tanks” and “cruiser tanks”, largely based on top speed and armor, with no significant difference in armament between them. (Infantry tanks were notably slow: generally around a 20km/h top speed. Conceptually, they were mobile pillboxes.) Interestingly, the manifest shortcomings of this distinction meant that the British were some of the first to embark on the idea of a “universal tank,” which is what eventually became the modern main battle tank.

          4. The Armored Calvary seems like the US uses strategic and tactical role defines how they describe the unit. So, any military unit for which the strategic or tactical role is strike and exploitation gets designated ‘Cavalry’. The US Army having ‘Armored Calvary’ and the ‘Airborne Calvary’.

    2. Yes, thanks for aiming another shrewd blow at the apparently deathless myth of the failure of the Maginot Line. It’s a myth which just seems to useful, to too many people, to allow to die. Anglo-Saxon scholars, in particular, seem to love rubbing their hands with glee while they talk of the French “hiding behind the Maginot Line”, while the Germans came elsewhere. (I’ve always wanted to ask such people where they think Dunkirk is). The fact is that the Line was built across the only part of the country which had a direct border with Germany, thus preventing a lightning assault before the French Army could completely mobilise. After 14-18 the French were obsessed with avoiding another war on their territory, hence the plan to advance into Belgium and fight there. But that could only work if the border with Germany was well defended.
      In the end, the German victory was probably down to three things. One was blind luck: the weather was good, the potentially suicidal decision to make the main thrust through the Ardennes (have you seen the Ardennes?) actually paid off, and the French High Command, never very keen on the war, was pushing to give up almost at once Second was German tactics (air-ground coordination and dislocation of command and control systems) to which, at that point, there was no answer- though the French did try to learn from Poland. Third, the French failed to spot where the German main effort was actually coming until it was too late: they thought that nobody but a lunatic would try to come through the Ardennes with more than a diversionary attack. (It’s not true that they thought the Ardennes were impassable: that’s another myth.)
      Any chance of a special issue on the subject?

      1. The Maginot Line was also supposed to help limit the number of men you’d need for the French Army. If it can funnel the Germans into Belgium, the area between the fortifications and the sea is far shorter than the kind of front lines the French had to hold during WWI. Shorter front lines let you achieve the manpower density you need to combat with a smaller army.

        Also, one of the problems the French had in WWI was that much of their ore mining and steel production was in their north east, in territory the Germans overran in their initial push. I’m not sure if it was a major impetus behind the Maginot Line, but if it can push the combat further north then it would allow France to keep those resources under its control. (Which should certainly help for keeping the industrial production of gear and weapons going)

        Sure, Germany might choose to assault the Line directly instead – but it should still slow them enough to let France mobilize, and it should still let them get away with fewer soldiers as it wouldn’t be quick or easy for Germany to make vast breaches in the Line. (And while in theory they could spread out once past the Line to lengthen the Front you’d need a vast hole blasted through it in order to even hope to be able to bring through enough supplies to support those troops. A narrow breakthrough just means it gets interdicted with artillery fire from the flanks (which can’t close the breakthrough, but can certainly cut down rate and which you can move troops and logistics through it)

          1. Really? I read that the artillery couldn’t fire backward, in case a position was taken.

          2. Some of the artillery was in casements and doesn’t look like it could have pointed backwards, but the forts of the line definitely did have guns that could cover their rear.

            In fact in 1944 the Germans were occupying it against the advancing Allies, and while it was mostly bypassed by the forces pushing east, small portions of the Line near Metz and in northern Alsace were attacked by the US on the way to Germany.

            It would have been pretty useless as a barrier against the Allies if its guns couldn’t fire back into France; and so the fact Germany used it as such seems to show that a reasonable amount of its firepower could be used on attacks coming its rear.

            (And finally the German offensive Operation Nordwind in January 1945 had to deal with portions of the Line that had been occupied by Allied forces – though that attack would be coming from in front of the Line)

      2. A fourth element can be added in that the Maginot Line was designed under expectations of stronger Franco-Belgian defensive cooperation. The idea was that one of the reactions to increased tensions with Germany would be for French forces to reinforce Belgian positions.

        Then Belgium shifted back to a more solidly neutral position¹ and the French had to wait for war to actually break out between Belgium and Germany before they could send in reinforcements. How quickly the Germans overcame Belgian defenses didn’t help.

        1: How solidly? The Belgians fielded a tank design that could only practically fire to its _rear_, (the T-13 Type II), so as to prove they had no offensive aims. They did realize how silly this was before the war so the T-13 Type III and the T-15 had more traditional turrets.

        1. this is the first I’ve heard that the T-13 TII fired backwards due to political considerations. do you have some citation for this claim?

          1. No direct ones alas, I found out about it by way of research done by Avalon Hill and Multi-Man Publishing for the vehicle/ordnance notes in Doomed Battalions.

        2. I maintain that the Allied failure to use the Mechelen Incident and the brief wavering of Belgian neutrality to occupy Belgium in force was the single biggest blunder on the Allied side of the war.

  11. Another great article! One of the interesting points was that the castles exist because of a need to provision your men in the field. So, in fantasy novels where the armies don’t have this constraint, it can make the castles somewhat useless.

    Immediate thoughts were of “fluff” Dragonlance novels where the knights in a castle are flabbergasted when the opposing army in a floating citadel just flies right over them without engaging (they have their provisions in the citadel, so why bother attacking?). Meanwhile, ASOIAF (with two episodes of GoT supporting this) imply that there will be a battle against the army of the dead in Winterfell, when by all rights the dead could simply march on past the castle and keep going since they have no concerns about provisions either.

    1. The Army of the Dead might not care about taking control of the countryside, but they do care about killing people so they can add to their army! In this case the resources they want to gain is the bodies of the very army that’s manning the walls of Winterfell.

      1. But they can just bypass it for easier targets and then wait to starve out the defenders. Nothing’s forcing them to commit against their enemies strongest point.

        1. The issue here is that the dead need a lot of men to bottle up the castle and keep the garrison from causing trouble as they march south — raids against the line of march, attacks on the investment of other castles, getting hit in the flank or rear as you try to cross Moat Cailin or the Neck, that sort of thing. In particular, you need to leave behind enough men to (1) maintain the siege and keep the castle fully invested and (2) prevent the garrison from simply marching out and destroying your besieging force in the field. That takes a lot of men — at a minimum you’ll want some fraction more men in your force left behind than were in the castle.

          Then you have to do this for every other castle. For all that “The North” is generally just shown as “Winterfell” in the show, the books make clear there are a number of midsized castle towns on the way, too — Winterfell is just the biggest. Once you start leaving men behind to keep Last Hearth, Cerwyn, White Harbor, Karhold, Dreadfort, Widow’s Watch, Hornwood, Torrhen’s Square, Deepwood, &c. under siege while you march past, you suddenly have no army left with which to take Moat Cailin.

          Feist in particular does a much better job of expressing this problem — a significant chunk of the plot of A Darkness at Sethanon is driven by this very issue, and it comes up again in the later books in other contexts.

          1. So how did armies in the 20th century develop bypassing and overcome the dread of leaving undestroyed enemies in their rear?

          2. I don’t know for sure, but I suspect armies in the 20th century were able to handle bypassing enemies for some combination of the following reasons:
            1) Vast increases in firepower. You no longer needed to leave a covering force larger than the garrison to be able to discourage the garrison from breaking out and raiding into your rear. Instead a smaller force with rapid fire guns, machine guns, or even on-call artillery support could do the same job. (And said artillery can now reach from dozens of km away, rather than having to be basically co-located with the covering force)

            2) Vastly improved logistics. You no longer needed to disperse your army to forage food and supplies as you moved, so you could move faster but also move in a more concentrated way and be less vulnerable to small forces in your rear. And units can carry enough supplies with their organic transport to handle temporary loss of their supply line should that bypassed force manage to block it for a couple days.

            3) Related to 2, those logistics allowed vastly larger national armies. You could afford to detach covering troops; or bring up less capable troops to perform that role, without overly weakening your front line forces.

            4) Faster movement – if you can move past the bypassed force on road, rail, or by steamship you can get out of range of where they could easily affect you.

            5) Improved communications (telegraph, telephone, radio) – each covering force isn’t on its own. If doesn’t need to be strong enough to defeat a breakout of the bypassed enemy, only to delay them (which machine guns and artillery are great at) and call for support from a fast moving relief force.

            6) Fortresses were less effective at buying time. Something the size of a castle could usually be reduced by your army’s follow-up heavy guns and infantry in weeks rather than months; so you’d be able to get those covering forces back sooner.

            Except for the WWII Pacific War island hopping I still think it was rare to leave large numbers of enemy troops in your rear for any significant length of time — even though armies were more willing to do so temporarily to maintain operational momentum and leave it to follow-on forces to deal with those temporarily bypassed pockets of resistance.

          3. @Michael Alan Hutson: They largely didn’t until what Prof. Devreaux terms the modern system came about. And even then, there was still a great deal of consideration for not leaving fortified defenders behind you — though by the time WWII erupted, the idea of simply isolating the enemy in their fortified stronghold while the rest of your force marched past was replaced with instead reducing the ability of the stronghold and its garrison to threaten your army and its supply train, and then later simply moving so quickly that the fortified defender was unable to respond.

            Consider the entire Pacific campaign in WWII as effectively being the crushing or reduction of one fortified stronghold after another. Bases (Rabaul) or islands (Truk/Chuuk) that weren’t directly taken had to be reduced by air and sea attack so as to prevent forces based there from sortieing out to attack forces along the line of advance — or supply lines. The liberation of New Guinea could not continue until Rabaul’s ability to operate ships or to launch airstrikes against fleets operating off the island was eliminated. Similarly, advancing up the Central Pacific (past the Carolines) was barred by the fleet base at Truk, so once the Allies had secured the Marshall Islands, they wrecked as much of the infrastructure at Truk as they could. The attacks on Taiwan prior to the invasion of the Philippines follow the same model of preventing forces within a fortified position from being able to threaten your forces as they moved in on your objective.

            On paper, the Allies certainly could have gone straight for the Marianas in July or August of 1942 — after all, Yamamoto and Doolittle had both demonstrated that the deep strike against core areas was possible. But had they done so, any invasion force would have found itself under attack from too many axes of threat to handle, and replacement troops and ships being brought up from Hawai’i or Samoa or Australia would have been harassed and sunk by submarine and air attack out of Truk or Rabaul or the Carolines or Japan the entire way, which is exactly why even as late as WWII you simply could not leave an intact, fortified defender behind you. The landings at Inchon during the Korean War created the same problem for the DPRK.

          4. Let’s take a brief moment to appreciate the manpower advantages of the Allies in Europe. The two largest nations fighting were the US and USSR. (British Indian forces having their own front against Japan.) While the US was fighting a two front war, the Pacific Theater was light on man power and heavy on capital taking only 15% of US resources.

            The scale of the manpower difference is hard to express. The counter attack to encircle the German forces at Stalingrad was on a scale of Barbarossa.

            The US in France had the spare manpower to detach an army group to invest the fortified ports that were isolated. But, this led to the Anglo-American army lacking a strategic reserve. Which would bite them in the arse when the Germans would once again see the Ardennes as tank friendly highway.

          5. The Pacific War between the US and Japan represents something of an “easy mode” example of how to get away with leaving behind encircled and reduced defenders of isolated garrisons… because all the garrisons were islands.

            A base like Truk presented considerable threats to the supply lines and rear of any force that tried to bypass it, but these threats would necessarily take the form of large air units (which required large amounts of fuel and precision machinery that could not be sourced on Truk proper) or large ships (which weigh thousands of tons and can be targeted when in port). There was no equivalent of “a couple of dozen men slip out of the castle’s sally port to burn the supply wagons of the enemy army,” no casual way for the garrison on Truk to threaten US forces without access to fully functional heavy equipment.

            Thus, in a sense, it didn’t matter how many tens of thousands of soldiers the Japanese piled up on Truk. On the one hand, the garrison would probably be able to supply itself with the bare minimum to physically survive (if only by forcing soldiers to engage in agriculture, not unheard of in the IJA as I recall). On the other hand, those soldiers would have nothing to do- the base could still be bombed into ineffectiveness from a distance and their presence wouldn’t help, because it would lose the ability to safely harbor ships or support large units of aircraft.

      2. They could just leave behind a small force that would still outnumber the defenders several times to starve them out, while the rest of the army marches south.

        1. Per OGP’s talk about the difficulties of coordination and organization, I’m not sure that the army of the dead had much concept of operations or tactics beyond “Charge!”

          1. As far as I can tell, they’re a magically controlled hive-mind. They probably (ironically) have *better* coordination than the living.

            (Of course this requires anything in *ASoIaF* worldbulding to make any sense, which is a big ask.)

          2. @Tiercelet: I don’t think we can blame the books for this one—their worldbuilding vis a vis the Army of the Dead’s coordination is pretty sparse because we haven’t really seen the army yet. I don’t recall any scenes in the books with more than a handful of wights—certainly nothing like an entire army executing siegecraft against a prepared fortress.

          3. Eh. The White Walkers are about as smart as humans. And they have perfect control over their soldiers. I understand that they have limited siege know-how. The oldest WWs are from the early Bronze Age, a time when armies and strategies were not very sophisticated. But they should be able to grasp very simple tactics like starving your enemy out.

          4. Hypothesis:

            The White Walkers have perfect telepathic control over their undead soldiers, but their span of true control and attention is merely human. As such, they cannot provide detailed mental direction to units doing a lot of different things all at the same time.

            One White Walker can easily direct two thousand ice-zombies to do something like

            But suppose said White Walker is trying to direct those same two thousand ice-zombies to simultaneously:

            1) Maintain a tight sentry-watch on an enemy castle.
            2) Maintain a tight sentry-watch to the rear in all directions in case any wandering human armies bump into his force from behind,
            3) Patrol the countryside well enough to discourage any obnoxious protagonists from smuggling supplies in or out, and
            4) Gather materials to construct field fortifications and dig trenches to discourage any sudden raids by obnoxious protagonists forted up inside the castle.

            Our White Walker friend is still only one near-human man with only one brain to keep track of all this, and a bunch of zombies aren’t going to be much help when it comes to delegating the details.

            If true, this would explain why the White Walkers and their army of the dead might display excellent coordination (i.e. “they act like they have magical radio control implants inside their soldiers’ brains”), but poor sophistication (i.e. “they only have a few dozen actual operators in the entire army who know how to work the control implants, so the bulk of their soldiers spend all their time doing stupid, easily comprehended things that can be done on literal magic autopilot, with no supervision or coordination.”)

          5. Simon_Jester, what you describe sounds a lot like the situation in Norman Spinrad’s satirical science fantasy novel “The Iron Dream” (story within a story “Lord of the Swastika”). The telepathic Dominators control a horde of mutant anencephalic Warriors who can be commanded to march and attack in unison but otherwise can’t do much more than attack enemies on sight.

        2. The castle contains dragons, a greenseer and a sizeable collection of dragonglass weapons along with people wield them. If they ignore the castle those forces could potentially raid their army as it marches attriting the dead and potentially numerous white walkers as well. Without intervention of the Night King, the dragons can rapidly destroy as many dead bodies as he can animate. And while the Night King is difficult to kill and can potentially kill dragons and any other enemy, he’s not invincible and anytime he engages in battle there’s a chance he could be killed and the entire army destroyed. In the show, by a Valyrian steel armed assassin after facing off against dragons, but potentially even a lucky dragonglass arrow could have ended him.

          So the castle still serves a purpose of protecting a military force that can raid from it to deny the enemy control of territory and attrite the enemy’s forces.

          His main error was not doing absolutely anything rather than personally engage in combat, but the power of dragons to destroy the rest of his army without his intervention may have forced his hand to an extent. The dragons would also have made a seige difficult, Of course his own dragon not to mention magical powers made resisting a siege difficult, but if his goal is to avoid exposing yourself to the enemy that limits his ability to counter them.

          Also, it’s entirely possible he *did* intend to lay siege to the caste and move on, and the attack was the initial hasty assault referenced above and previously, but once it suceeded in breaching the castles defenses he became too caught up in the attack and continued on personally leading it even when he should have fallen back….or perhaps the issue was always just getting rid of the dragons and the rest of the attack was merely getting rid of extraneous threats from other humans and attacking at night when humans were disadvantaged.

          Anyway, certainly the forces at Winterfell were the only ones that had any chance of stopping him, since the rest of the world had zero dragons and very few Valyrian steel or dragonglass weapons so getting rid of them had to be the priority.

          1. Possibly the Night king should have creatd his *own* fortified position and tried to force them to come to him, or if he had no means to do that, simply march south and force them to attack him while he was traveling instead of him attacking their castle. Hard to say, because the key part still requires him to expose himself to destroy the dragons, by attacking Winterfell he can choose the time – night and before more preparations can be made, but his opponents have their choice of location, one of the most defensible castles in the world. If he avoids Winterfell he can avoid attacking a castle, but his enemies can use Bran for scouting and attack him at a time of their choosing, at least during the day, and whenever he is more vulnerable to the extent that he is more vulnerable at some time. It also gives more time for other forces to gather and arm themselves with dragonglass, any piece of which can destroy a white walker and therefore a sizeable chunk of his army or potentially himself. He may have figured that fighting the dragons was the most important part and so the most important part was fighting at night when he was less vulnerable to missile fire, while the protection from the castle and the rest of the army was insignificant.

            Also, he’s been behind the Wall for hundreds maybe thousands of years. He’s probably encountered some form of fortifications before, but certainly hasn’t had a great deal of experience with modern (for the time) siege warfare.

    2. I expect the plan for ASOIAF is to have a massive battle against the undead at Winterfell, though I imagine many of the circumstances would be different than in GoT; one thing to keep in mind is that Winterfell very well may be a place of supernatural importance*. We have no book-insight into the Others’ plans/intentions/reasons, but it’s not impossible that their decision-making will be influenced by awareness of Winterfell’s magical significance (whatever exactly that is).

      * On the presumption that Martin scatters intriguing tidbits about without knowing exactly what he’ll follow up on, hard to make definitive predictions, but: it is, of course, the place that Winter fell, the last time. There are teased connections between the hot springs and supernatural sources of fire-magic. And given that the rational attitude for a reader to take is that “Old Nan’s folklore is true,” we must assume that the castle itself was invested with magical properties by Bran the Builder, and for that matter “there must always be a Stark in Winterfell” may be an important instruction and not just a bit of dynastic propaganda.

      1. In my opinion George R.R. Martin is just one of the writers good at world building but bad at story and especially tying loose ends up. He’s making loose ends at a much faster rate than dealing with them. I think this is what he really enjoys and he doesn’t have much of a plan. Considering the rate at which the new books come out he’s probably burned out with ASOIAF. 3 years between the first books, then 1 year, 5 years, 6 years, 10 years and counting. And as for plans it was originally planned as a trilogy.

        1. My hypothesis is different: that he’s good at generating story as “what would these characters do next?”, but does have a Plan, that the characters don’t want to go to. Especially if Season 8 is any guide. Like he’d probably be better off just churning out books in a series that never ‘ends’ the way that history never ends but just keeps going.

          Though also, yeah, generating more and more characters. I think Arya is the only POV shared between books 4 and 5? So that’s like 17+ live POVs for book 6…

          1. As Aristotle observed long ago, a story that is too large can’t be taken in altogether, and so loses its aesthetic impact.

            A long saga should shift from character to character and the prior characters should fade out because THEIR stories have been resolved.

          2. Books 4 and 5 of the series suffered from the fact that they were originally one novel that Martin decided to split into two so that he could follow the stories of a greater number of viewpoint characters all at once. Since 17+ characters is too many to follow in parallel in a single novel, he split it into two halves with ~10 characters each.

            When your novel starts reproducing by fission because of the sheer number of viewpoints you’ve introduced, you know you’ve done something wrong.

  12. >second by creating a base for a raiding force which can at least effectively prohibit anyone else from efficiently extracting revenue or supplies from the countryside.

    This is one historical tactic that actually does show up in an RTS! Starcraft 2 has a tactic called a “bunker rush,” where you take a couple of Reapers or Marines (cheap early-game infantry) and build a bunker right outside the enemy base. The reapers jump in, shoot some workers, and if defenders show up, they retreat back to the bunker and hide. From inside the bunker, they can easily defeat most early-game defenders, which means that the enemy can’t kill the harassers – only keep them bottled up until they build a big enough army to destroy it. And if they ever let their guard down, you pop out of the bunker and kill more workers.

    In short, a single static fortification lets your raiding force dominate a much wider area than its attack range would indicate, and means your enemy needs to spend time and money (and attention!) on building a bigger army, which slows them down and lets you get ahead economically.

      1. Well, RTS games tend to abstract that kind of thing out, but the practical equivalent to this in real life would be to infiltrate a raiding force to quickly seize a defensible location inside the enemy’s territory, hastily putting up some field fortifications broadly analogous to a legionary camp or something just to ensure their own security unless confronted by a much stronger force than themselves. The raiders would probably be trying to steal enough food to keep themselves fed anyway.

        If no force mobilizes to repel the raiders, eventually they hang around to stay, set themselves up as local overlords and start fortifying their own bases of operations until they grow up into something like castles. I imagine this is broadly speaking what it felt like to be invaded and taken over by Vikings, for example.

      2. RTS games don’t really have supply lines, (although reinforcement routes can sometimes play the same strategic role), so you don’t, you just retreat once the bunker becomes too dangerous to hold. If it helps, you can imagine that the SCV who builds the bunker also stocks it with enough food and ammo for your raid.

        1. Turn-based games too. Civilization, I think units take production to support, but they’re magically supported whereever they are. Colonization, food for your colonists inside the settlement or to grow horses is a big deal, but you can park an unbounded number of people (and horses, if mounted, or in storage) outside, who don’t take any support; likewise any units in the field. It’s a weird mix of micromanaging resource control and not needing resources at all…

          1. To be fair, Colonization would become unplayable if you had to feed all units in the field the same way, because a major gameplay mechanic involves sending scouts to explore the wilderness. Historically, at least in the Americas, such expeditions were usually able to feed themselves for long journeys, or were operating out of ships that could carry enough supplies to last for a very long time.

            I think the premise behind that mechanic is that the units not integrated into a colony are just foraging/hunting for their food in the notionally vast wilderness between settlements… but that runs into obvious limitations when someone abuses the mechanic, especially since there IS the assumption that you’ll amass actual armies by the end of the game.

    1. I’d be careful about using Starcraft as an illustration. I mean you can find interesting examples and principles, but there so many oddities. If something makes sense, it’s by accident.

      Bunkers in SC are one of the most fragile structures ever, all in the name of game balance. Starcraft is strictly a zero-sum game, to the point where SC players worry about having any spare money at the moment (the rationale is that all factories should be producing units at all times – if you have surplus money, you don’t have enough factories. All available money should contribute towards victory.). Formations don’t matter and armies are often called “blobs”. For example if someone attacks your infantry with an area weapon, it never works to spread them out. Sight range is comically short – units can shoot perhaps 2-3 times before they’re engaged in melee. Intelligence gathering is usually done by performing a suicide run into an enemy base to see what structures the enemy has built (because it determines what he can produce). You mostly can’t detect movement of enemy armies – scouting tools are not good enough for that. The interplay between unit types is often defined explicitly and arbitrarily, for example to beat a cluster of siege tanks (artillery) you throw huge, slow, short-ranged spider robot at them (Immortal), because developers like it that way. The game is built on hard counters, and that means you use unit X against unit Y and not tactic A against situation Z. Terrain barely matters in the game – there’s no cover, no terrain that slows you down, no neutral structures infantry can garrison. There are no pincer maneuvers because if you split your army it will be beaten by a single concentrated army – the RTS equivalent of “stack of doom”. The maps are very, very symmetrical because competitive players insist on even playing field.

      If Blizzard made a racing game, it would have a “Tank”, Healer, and a Damage Dealer.

      The one genuinely interesting concept that SC has taught me is the timing attack. The best time to attack is once the enemy has paid for a new technology but before that technology has started yielding profits.

  13. Was an escalade really a bigger threat to medieval castles than treachery? Is there any research quantifying this? I would love to read up on the subject, because I always had this vague notion that treachery was the single biggest threat.

    1. I too am curious how that ranking was arrived at. Previous posts have touched a bit on the difficulties with both sapping and starvation as strategies, but not gone into great depth, leaving me wondering why starvation was ranked equal with treachery and above sapping.

    2. The catch is that there are two very different ways to evaluate “the biggest threat.”

      Is the biggest threat “the thing actually most likely to result in the castle falling,” or “the most dangerous thing the castle was prepared to face?”

      If a castle is designed to be extremely resistant to escalade, then as a matter of course it is very unlikely to fall to escalade. By process of elimination, most castles that do fall will fall to treachery, starvation, or other factors. And indeed, since attackers aren’t a pack of fools, they usually won’t even waste their time on a suicidally dangerous escalade attack, and will instead concentrate on starving the defenders out or figuring out how to successfully suborn a traitor.

      In one sense, then, the escalade is a relatively unlikely threat compared to starvation or treachery. In another sense, the escalade is a huge threat and only by spending a great deal of resources (to build a whole castle in the first place) can the defenders avoid it.

    3. From what I have read (mostly 100 years war stuff) was that succesful escalades were done at night, stealthily. More common was that as soon as the siege began, there were negotiations between siegers and besieged at which point a future date was set when the castle would be surendered if no relief force would have shown up.

        1. I really want this sort of this to be captured in EU5. Sieges and forts defined many of the conflicts of the period and I’m annoyed by the game’s reducing it to just a waiting game.

    4. Your average castle was pretty small and often held only a small number of people permanently. Many escalades were surprise attacks at night or in bad weather. Others employed ruses to draw the garrison out (see eg The Douglas Larder) – once you had a dozen men inside the wall the game was over.

    5. Treason is basically impossible if you can’t find a prospective traitor who stands to gain something *and* believes he or she will get away with it. Consequently, the smaller a fortification is, the more difficult it is to take them by treason; and even harder in feudal-era situations where people mostly don’t survive relocating to new communities (so a traitor would not expect to escape a reputation by moving, even if they actually did get their pay).
      Because pre-modern fortifications are nearly always built to minimum possible level, the vast vast majority of siegable locations were on the smaller end of the spectrum. Sure, people did sell out uncles and whatnot, or lords they’d known their whole lives, but mostly people just looked out for the people they knew and didn’t trust packs of jerks with swords who showed up from over the horizon with the announced intent of killing and looting.
      Ladders are much simpler to work than traitors; for them, you just need a big enough pack of jerks.

  14. There’s one other major impetus to fortification that so-called Real Historians, being so-called “Professionals” who do so-called “serious history” with so-called “citations” never address: People don’t like dying if they can avoid it, and if they can’t, preferably put it off till later. Or as I like to cal it, the “I Don Wan Die!” School of thought. Surprisingly, studies have shown that having large, sturdy walls between you and people who want to kill you is often a good way to avoid death, although so-called “Scientists” with their so-called “evidence” and so-called “logic” haven’t yet been able to explain why.

    [Yes, this is a joke. Or at least half a joke. I think there might be some interesting historical study of Prospective versus Retrospective Fortification efforts. That is, the use of fortification as a response to current or recent conditions compared against expected future needs.]

    1. Someone did a controlled study on whether a parachute helped when jumping from an airplane. Their conclusion was No, though they did observe that these results might not hold if the airplane was farther off the ground — like, in the air.

      1. Reminds me of the anecdote when they trained a neural network to recognize tanks on aerial photos. It worked nice at first, with training images at least, but stopped when they tried it on new data. It turned out… all the photos with tanks were made in sunny weather. Many others had bad weather. The network didn’t learn to spot tanks, it learned to recognize sunny weather.

        * * *

        When you think about it, it’s a bit like survivorship bias. You can reach wrong conclusion using correct logic and perfectly good statistical data. There are graphic examples from military history.

        WW2: US bombers were examined for bullet holes to find the best places for extra armor. Most holes were on the wings or gunner’s cabin, so extra padding would be added there… except Abraham Wald had the imagination to think about planes that were hit in the fuel tank or pilot’s seat. Instead, he proposed to add extra armor in places which were consistently left unscathed.

        WW1: “When the Brodie helmet was introduced by the British Army during World War I, there was a dramatic rise in field hospital admissions of severe head injury victims.[citation needed] This led army command to consider redrawing the design, until a statistician remarked that soldiers who might previously have been killed by certain shrapnel hits to the head (and therefore never showed up in a field hospital), were now surviving the same hits, and thus made it to a field hospital.”


        1. Often called the “Russian Tank Problem”—it points out a serious issue in an intuitive way and makes a great story, but sadly it seems to be something of an urban legend.

          Better examples are probably the recidivism systems or loan qualification rating systems, which in the former demonstrably replicate racial bias (as in—provably over-estimate re-offense rates for Black offenders and under-estimate them for White offenders) and in the latter use zip-code-of-residence as an input feature and thereby train redlining into the model. But these don’t have the same kind of intuitive punch (and humor driven by transparently universal agreement—we can laugh at the obvious Badness of failing to identify enemy tanks, but to America’s great shame there is not similar consensus in public discourse on the undesirability of automatic racial discrimination; and in any case it’s clearly no laughing matter) so they don’t pop up as much as examples.

  15. “the people actually living in the fortified point (or close enough to flee to it). . . might well place a higher premium on their own safety (and their own stuff!) than an abstract strategic planner would”

    Any any rate, “people prefer not to die” is sufficiently obvious that it doesn’t require a lot of academic attention.

  16. Actually, what was happening fortress wise in the near east? Because on the one hand the Arabs don’t seem all that proficient in sieging down cities (the Almoravids and Almohads lost almost every siege in Iberia), but on the other the Europeans did adapt a lot of their defensive architecture. Or am I drawing a false paralel between the Maghrebis and the Arabs of the near east?

    1. I believe both Arabs and Europeans were learning siege raft and fortification from the Romans via the Byzantines.

    2. North Africa / Spain in the early medieval period has differences to the Near East. The ‘Arab Conquest’ did include a new ruling class and some population movement, but most of it was converting the people already there.

      In North Africa there wasn’t much besieging, I speculate because the major cities are all ports. Naval power would move your armies around faster, and instead of besieging from land, you’d rely more on blockade.

      Both the Almoravids and Almohads started as religious mass movements, the poor in North Africa overthrowing the decadent elites. (Yes, this is Ibn Khaldun territory.) When they moved into Spain, the local ‘Moors’ preferred their decadent lifestyle, so fought against them, often joining forces with the Christians. I speculate that the Almoravids and Almohads were crap at sieges because the skilled combat engineers had either been killed by them or weren’t co-operative.

      1. IIRC, the initial arab conquests of North Africa had some quite lengthy sieges (to the point where the siege/army camps grew into their own proper cities,

  17. I’d emphasize one of the points you made. A king of a country that’s got a lot of castles, or walled towns, has a defense in depth for the country. Even if an attacker can defeat any one of them, or any dozen of them the time and lives consumed in taking them or convincing them to surrender means the attack is very slow moving and you’ve time to call up a field army and go drive them off.

    As noted, those fortified points can’t really be safely bypassed, so collectively they raise the cost of attacking extremely high. Thus even the most powerful enemy is unlikely to be able to make an single existential blow against your nation. The best they can likely hope for in a campaign season is to carve off a bit of your frontier by taking over (and managing to hold against counterattack) a handful of castles or fortified towns.
    And even then the costs in money and lives may be such that they’ll need a lengthy recovery period before really being able to try again.

      1. Which is why you needed a royal license to crenellate. Kings often had a network of royal castles (often succeeding the Anglo-Saxon ‘war towns’ – the fortified places built to contain the Vikings), plus a policy of demolishing unlicensed fortifications.

    1. That was the theory behind the several lines of fortifications – mostly towns – built by Vauban under Louis XIV. Showed their worth in 1706-14, when they imposed sufficient cost on Marlborough to force a treaty on relatively favourable terms.

      Hungary after the first Mongol invasion did the same- built stone castles. Later Mongol invasions were limited in their foraging and had to turn back (when they were hit by sallies at vulnerable points as they retreated)

      1. This makes me think that maybe show-Cersei was right and show-Robert wrong about their castles vs. Dothraki. Especially Dothraki in a Westeros that is not overrun with grass for horses.

        1. Well it depends, the actuall Mongols did figure out various ways to take walled cities and fortresses, including simply employing non-Mongols who knew how to build siege engines etc. But obviously that wasn’t universally successful for all Mongols or all horse archers at all times. The book/show Dothraki seem to have been stymied pretty effectively by walled cities, but presumably the fear would have been an army of Dothraki combined with a – presumably smaller – army of of Westerosi rebels/loyalists, thus incorporating important knowledge and experience of siegecraft. There would be a lot of challenges in getting the Dothraki army to Westeros and keeping them operational in an unfamiliar environment, but it’s not impossible, particularly if you have a great house helping you – as they in fact did in their original plan and as Robert feared they would.

          And really, maybe you don’t need a hundred thousand Dothraki to completely outnumber opposing armies anyway, just enough to supplement native Westerosi forces and change the balance of power.

          I’d say they both have points. The threat of Dothraki sweeping over the kingdom in an unstoppable army was highly exaggerated. But the threat of Dothraki allying with a great house or two to change the fragile balance of power was real, even if not the most likely possibility, and something to be addressed.

  18. “Clifford Rogers has already laid out a pretty lay-person accessible account of the medieval siege playbook (in Soldiers’ Lives Through History: The Middle Ages (2007), 111-143; the book is pricey, so consider your local library)”

    Would it be breaking any rules to point my fellow ACOUP readers towards that excellent free resource known as Library Genesis?

    1. It might break less rules to point your fellow ACOUP readers to Archive dot org. If you make an account with them, they’ll let you borrow books, assuming no one else’s reading them at the moment; the 1-hour borrowals are apparently perfectly legal.

  19. Krak de Cheveliers and Beaumaris, two of my favorite castles! Beaumaris is perhaps the ultimate in concentric castles and if completed would have been a grand place to live! The Krak practically screams ‘Come on if you think you’re hard enough!’

  20. “Out-of-context quotations are a monument to the stupidity of man.” —George S. Patton, probably

    No fortification is ever designed to be absolutely impenetrable (or perhaps most correctly put, no wise fortress designer ever aims at absolute impenetrability; surely some foolish ones have tried).

    This conjures the image of a proud architect showing off his absolutely impenetrable fortress to the local lord, who politely asks where the hell the front door is.
    “There is no front door. Doors would compromise the absolute impenetrability.”

    All of this despite the fact that the crusader army was uncommonly large by medieval European standards, numbering perhaps 45,000.

    Though since it was composed of petty lords and retinues from across most of Western Europe, and lacked a clear commander for much of the Crusade, the poor coordination/organization was even worse than it would be for the typical medieval king’s army.

    This is, by the by, more true in real warfare, where coordination is limited by communications technology, than it is in film or video games, where armies appear to mostly communicate by some form of instantaneous telepathy (it is amazing just how many clever sounding movie or game assault plans fall apart once you imagine trying to coordinate them with nothing more than shouting, or even a radio).

    On a related note, I’m surprised so few fantasy stories justify that dramatically intricate coordination with actual telepathy. The only example I can think of off the top of my head is Mother of Learning, on the rare occasion that its fight scenes escalate into complicated military operations.

    subdividing towns into walled districts (very common in video-games for memory-management and loading reasons)

    I don’t think that’s the only reason; otherwise, fantasy novels would almost never have internal walls dividing their cities into distinct districts.

    The other big reason is, of course, that this kind of clear delineation makes thematic intent easier to convey. A wall serves as a very straightforward reason for the noble’s quarter and commoner’s quarter being so cleanly divided, and one that’s easy to justify—usually with defense-in-depth, sometimes with the implication that the nobles are as worried about their own commoners rebelling as they are with external enemies. And on that note, it also serves as a visual symbol of the callous attitude that the ruling class generally has towards their laborers’ problems—the wall serves to keep the poor people’s problems away from the rich people without actually solving anything.

    And that’s just scratching the surface, focusing on elements that appeal to me personally—internal walls in a city are a remarkably versatile writer’s tool.

    1. David Eddings’ Belgariad and Malloreon, and I think some of his other works, feature wizards with telepathy. This is occasionally used to coordinate armies.

      Most of said wizards can also shapeshift into birds, and regularly use this ability to get aerial reconnaissance in dangerous situations including warfare.

    2. I think one of the Discworld novels had someone build an airtight refuge for themself.


      “I’m surprised so few fantasy stories justify that dramatically intricate coordination with actual telepathy”

      Hah! Or even mundane things like pigeons. (I read Clavell’s _Shogun_ recently, and it did have quite a lot of messenger pigeon work, including poisoning them or hunting with hawks.)

      _The Hobbit_ used talking Ravens nicely for communication and surveillance; one of my more disappointing moments was when I wondered why they weren’t ubiquitous through Middle-earth.

      1. Much worldbuilding has vast holes where the writer simply assumed that life as he knew it was the law of the universe.

        1. Goes back to Tolkien’s comment that a fiction has to use a lot of commonplace elements (familiar trees and buildings and such) if the reader is to suspend disbelief. Making everything strange makes it incomprehensible and unbelievable (and unreadable).

          1. Having people see clearly, when you have specified a moonless night with no artificial illumination, does not help suspend it.

      2. The talking birds in The Hobbit? Yeah, you don’t see them all over the place.

        Maybe it’s because most people in the setting have trouble convincing talking birds to do stuff.

        If you’re personal friends of Gandalf or whatever, you can prevail on your connections and convince the sentient birds to feed you some intel and carry messengers for you. But most of the time, they prefer to just stay aloof and avoid getting entangled with what regular people do.

        1. The ravens talk to the dwarfs because dwarfs made nice shiny babbles that the ravens covet. The eagles talk to Gandalf because he healed their lord of an arrow wound. The magical race of thrush talks to people of the Dale because the plot needs someone to tell Bard the weak spot of the dragon.

    3. There’s a nice tale in the Riddlemaster series (by Patricia McKillip) where a king hired someone to build him a house safe from his foe, and after a time, he decided he was safe and to go for a walk. That was when he found that his foe had built it. . .

    4. I do note that we sometimes *do* get walled quarters… In the case of jewish ghettoes. (this was often a selling point, the idea being that the jewish quarter would be comparatively safe from mob violence, how well that actually worked seemed to vary)

      1. But a much later phenomenon than the period we are talking about; it was an early-modern, gunpowder era thing. The first Jewish ghetto in Europe was that of Venice, established in 1516– and even that was not yet a ‘ghetto’ in the familiar sense,* but rather a ‘Jewish quarter’ in the same sense as the ‘Greek Quarter’ or for that matter Constantinople’s ‘Venetian Quarter;’ in other words, it was established as a Jewish neighborhood but residence within it was not mandatory; that came much later. So there was no need or desire, early on, to wall it off.

        *Although the word ‘ghetto’ derives from the Venetian-dialect name for the area, which had previously been a bronze foundry or geto.

        1. The 1084 charter establishing the Jewish quarter in Speyer had the Jews settle in a walled area separate from the rest of the city.

          Importantly, though, the Jews were to maintain and guard these walls themselves.

          (The charter explicitly says the walls are a measure to protect the Jews).

      2. I don’t think either I or Devereux claimed that cities never had separate sections walled off from the main part of the city, just that it’s not as common as fantasy novels and games would have you believe.

    5. Sanderson’s Way of Kings and subsequents books have magical telegraph and magic food production to take care of logistic and coordination problems. Sadly Sanderson sucks at anything large scale (I think mostly because of his exclusive use of internal viewpoint) so despite the fact that he clearly thought about it a lot most of his military operations and battles feel a bit silly.

  21. So, I was going to write a comment about how you seem to rarely see this kind of castles in China, but then decided to actually fact check myself. I’m glad I did, because there’s a whole nice rabbit hole you can jump into of the many and varied forms of Chinese fortresses and castles built and various times for much the same purposes of these European castles, for administering the countryside and to defeat local rebellions. As well as for groups and lords of less well off means to defend themselves.

    This is of course especially true during the period of Chinese political fragmentation and political unrest, where these fortifications multiply themselves across the Chinese countryside like crazy.

    Below post is in Chinese, but I think the pictures do speak for themselves XD.

    There’s also the famous which was part of the Great Wall complex, though given its highly remote nature the fortress itself was also very substantial.
    In the south of China, where central control was quite weak for long periods of time, there were also a style of private fortification that looks quite neat.

    1. Thanks for that. Fascinating to see how ‘form follows function’ works at opposite ends of Eurasia.

      I do notice that the Chinese castles still have square towers, where I gather European castles switched to round during the medieval period, most likely drawing on Byzantine / Near Eastern expertise.

      If you find any more good photos, please post them.

      1. So this was another fun diversion, I can’t say I know why square towers were more favored in China than round ones, especially since there actually are round towers (very rarely) on the Great Wall, which I didn’t know about until today, so they clearly knew how to build round towers, but deliberately chose not to.

        Speaking of round, there’s actually a quite different kind of fortification that I forgot to mention. These are not castles in the traditional sense, being not used by local lords to dominate the countryside, but rather by local clans for personal protection, and so are built to be more egalitarian. They’re the Hakka Round House.

    1. I mean, aside from the rather pat “by being the ones who built it in the first place” answer…

      As Dr. Devereaux points out, the Theodosian Walls seem very specifically and well designed to counter the exact “playbook” of tactics and tools the Romans themselves would normally use to breach a walled city. The big things the Romans brought to the table there were sophisticated torsion artillery and vigorous earthwork construction.

      For a besieging ‘imperial’ Roman army coming after Byzantine Constantinople… Well, the artillery is largely countered by setting up multiple rings of defenses that physically block lines of fire against the most vulnerable part of the main defensive line. They can punch holes in, or snipe at defenders on, the outer walls, but that doesn’t help much if they can’t get a clear line of attack against the main wall. And since they can’t get torsion artillery close enough to do that without building it relatively and dangerously close to the defenders’ outworks, that seems like it’d be a problem.

      So that leaves earthworks. The part where (again) you have to start building your mole/ramp/whatever from well outside range of the outer defenses, and push forward far enough to breach the inner defenses that are very high and separated from the outer defenses by clear fields of fire, makes this a daunting task. In principle, just about any fortification prior to the advent of gunpowder can be taken by building up a big enough siege earthwork,* the definition of “big enough” can be pretty intense (see Masada).

      So the most likely answer is that the besieging Roman army would stare at the defenses, mentally calculate the magnitude of earthworks required (large), go “fuuuuu-” for a while, then quietly stop to figure out if there’s any way to avoid having to do this. If the answer is “yes,” they do that instead. If the answer is “no,” then they go “fuuuu-” again for a while and actually build that earthwork. Eventually. Assuming no relief army chases them off or they don’t have to run away and defeat a barbarian invasion or six before they have time to finish the job or whatever.

      *(covering the work crews from the defenders’ gunfire with mobile shelters is prohibitive, so with gunpowder you have to go full Vauban and start relying on trenches to take fortifications)

      1. And I expect this was entirely deliberate: The greatest threat to a roman emperor remained his generals, after all.

    2. So the Romans would need two massive fleets, one to block the Hellespont and the other the Golden Horn for the Siege to even begin. At least one Legion in Asia to cut off supplies from there. Four to five Legions to meaningfully encircle the walls. Probably an entire road dedicated only to feeding the sieging force. Constantly harrassed by the defenders. Mountains of corpses for a city they would then have to burn down in the end.

  22. This whole talk reminds me of the Mongol invasions of Hungary, despite battlefield success they were unable to secure control of the land. Partially in there inability to take the major stone castles present, this only got worse in the second invasion because Hungary went from 10 to 40 stone castles.

    There was also the issue of attrition especially after the one major battle of the war, were the Mongols narrowly won after heavy attrition and fighting.

    1. It is also interesting to note of course, that other parts of the Mongol forces eventually got quite good at sieges via importing foreign expertise. Kublai Khan famously fought bitterly, siege after siege, in China in order to conquer it, in the process becoming an expert at siege craft.

      1. Kublai had the advantage that he wasn’t invading southern China with only a steppe army: He could draw upon all the resources of the heavily militarized (and quite familiar with siege warfare) northern China (as well as experts from farther abroad, like the muslim world)

        The mongol armies attacking Hungary had no equivalent denseley populated area to use as a base (the closest would be the Rus areas, and they were a long distance away and not nearly as populous)

    2. Defense in depth. Alfred the Great used the same principle for fighting Vikings. Check out the youtube video “How to Deal with Viking Invasions” on SandRhoman History channel.

  23. Good morning Professor Devereaux:

    Knowing that these posts are overviews of a very broad matter I’m curious if there are any regional differences in castles and fortresses as well as in periods apart from what you pointed out. You reference the well known (by me at least) motte and bailey type, so typical from Anglo Saxon and Norman period, and I’m missing some reference to French, German, Italian, Eastern Europe, Arabic and also Spanish castles.

    I guess you probably know that it seems Castile got that name for the number of castles, towers and so on that were in that territory. Of course there is so much diversity and over the centuries there are accounts of several tens of thousands of fortifications in the Old World. So any other tips to books on castles or types in this ocean of information?

    I really appreciate your work, I’m a big fan of acoup and I recommend it to my friends. Thanks for your insight!


    1. The earlier castles in Castila were of the type “castillo roquero” (rock castle), with the tower on top of a bedrock spur instead of a motte, so that they incorporate natural features of the land in the design of the building. Most of them are ruined now, like Cellorigo, Aitzorrotz, Bilibio…
      A later developed (and beautiful) one is the castle of Frias:

      1. The Auvergne in France is dotted with similar castles – sitting on the volcanic plugs (puys) of the region.

    1. There were walled districts in Chinese cities, too. I believe the Qing liked them — and you better not be outside yours at night.

      1. Chang’an during the Tang period had walled districts with a night curfew as well. I don’t know much about other postclassical Chinese cities and their structure, so I have no idea if this was just a peculiarity of a particularly prosperous dynasty’s capital or not.

        1. No, this was actually fairly common—I’m pretty sure Suzhou had a similar feature. (Sadly the reference is at home, so I’ll have to follow up on this later.)

          1. And long after anyone cares…

            “In the city of Suzhou, as in many other Chinese cities, a sort of ‘zoning’ system must have existed at least until the mid-Tang [ie ca 750-800 CE]. The city was divided into residential wards, market quarters, and enceintes exclusively occupied by local government offices, each being enclosed by walls and separated by streets and canals.” [Xu, Yinong. The Chinese City in Space and Time, 2000]. (163)

            Ff states that the rigid walled separation of the wards was reduced thereafter, although it then also discusses that nearly all “public” space in the early modern Chinese city would have been contained within the walls of public institutions (eg temples). I will note that the effect (as a review of contemporary urban landscape scrolls makes apparent) is rather similar to having the wards walled, since it’s only the streets (not even marketplaces) that lie outside the private walls; all that’s missing is internal gates barring passage. You still have the continuous-wall effect.

            Of course Suzhou is also particular because of its extensive canal network, which probably further restricted movement, but on the other end I’d say you have a similar effect in the alleys and off-main-street areas of modern Taipei—where the walls are often at the property line and continuous with the neighboring lots.

    2. Old Baghdad was built as circular city with concentric walls an compartmentalized neighborhood. It looks very cool but must have been difficult to navigate.
      Ancient Egyptian pyramid towns were divided into walled districts, one for the palace and high officials; another for the skilled artisans and the last and largest for the common workers. But that was about social control not defense.

        1. I see the resemblance. Only with Old Baghdad the green zone was in the city center. Concentric city defenses are common in fantasy. Look at Minas Tirith.

  24. > Recall that this is a defense which really doesn’t envisage enemy artillery (because armies with lots of effective siege artillery were not common in the often small-scale warfare of the period;

    Counterpoint: all the buildings hug the walls, which makes them partially protected by artillery hits. You’d have to hit them at a high angle. This is something Shadiversity brought up in his video about castles. This makes sense, because you’ve already said that this particular example of motte-and-bailey has projecting towers, which is a later innovation.

    In general, the higher the walls are, the more protection they offer from artillery and the more benefit from hugging them. By contrast, Japanese style castles very often had earth behind the walls – inner layers would keep raising much like terraces on a rice field. This makes them more resistant to direct destruction by artillery, but offers less protection for buildings inside, other than of course having to lob your projectile higher and higher. But naturally piling all that earth is very work intensive.

    1. Hm. I can think of a number of reasons why the buildings inside a castle would be backed up against the walls.

      1) If the castle is large and concentric, there’s a big keep in the middle of it. You probably shouldn’t build outbuildings up against the wall of the keep itself without compromising the defenses, so by process of elimination they need to go either against the inside of the outer walls, or in the courtyard spaces between the outer walls and the keep walls, which brings us to (2)

      2) Castles generally double as administrative and market centers, and as a space capable of at least temporarily housing bodies of troops over and above the minimum garrison required to hold the place. It’s a practical necessity for such a structure to have a large cleared area within the circuit of the defenses that can serve these various functions- as a market square, a place to gather the public in peacetime, a place for your lord’s retinue of retinues to pitch tents if they are so inclined, and so on. Again, you need a big open space somewhere within the castle, and it’s probably bad if that space is cluttered up with buildings in the middle of it. For practical reasons, then, the semipermanent and permanent outbuildings get built up against the walls of the castle where they’re out of the way.

      3) Besides, if you build your stables or whatever up against one wall of the castle, that’s one side of the stable where you don’t need to bother building a wall for it. 😀

      I kind of doubt it’s primarily about ‘artillery,’ since most of these castles aren’t going to see much siege artillery, beyond maybe the level of some guy with a burning rag wrapped around an arrow trying to lob it over the wall and set a thatched roof on fire or something.

  25. > But stone walls are a much larger investment in time and resources; they also require a fair bit more careful design in order to be structurally sound.

    Worth noting that the Japanese were really attached to their largely wooden castles. How did they do that?

    1. The wooden walls were backed by earth. Or another way of looking at it – the castles were basically terraces where wooden walls were used for earth stabilization.
    2. The Japanese had very elaborate and time-consuming system of wooden joints without using nails. There are plenty of them on youtube because they’re satisfying to look at.
    3. The wood was often laminated. Various processed were used to make the wood fireproof.

    My overall point is that you absolutely could persist using wood for castle walls, but there was a lot of extra work involved. That said, my personal opinion is that those castles wouldn’t stand up to the fierce military competition that took place in Europe. A particular weakness was bad quality iron available in Japan, which for example made katanas very brittle and not competitive with western swords. The Japanese were saved a few times by sheer luck, to the point where they started believing they were the Chosen People (Kamikaze – Divine Wind).

    1. The Japanese castles stood up to the fierce military competition that took place in Japan during the 14th to 16th centuries. The Japanese were a little slower to get started with gunpowder weapons than Europeans, but by the 16th century they were making muskets and cannon fully equal to European weapons. (Primary source for effectiveness is the book Firearms: A Global History, which among other references has quotes from a Chinese military procurement official who had run a competitive evaluation of domestic and various foreign muskets.)

      Stone construction was expensive in Japan, especially because the transport infrastructure was really awful by European standards in medieval times. Wood and earth was cheaper and could do the job. In the early 17th C, when a centralised government had established control, castles finally started being built in stone, although by this time the Japanese were well aware of what cannon could do and the stone was mostly to look more impressive and show off wealth.

      As for quality of iron and steel, for what time period? Like everybody else, Japanese smiths would vary the quality according to what was necessary and/or what they could get away with. In the European medieval / renaissance period Japanese (and Chinese) iron and steel seems to have been comparable quality. Europe did pull ahead in the early industrial revolution, but that is well after castles became obsolete.

      For swords, in both Japan and Europe the swords most likely to survive are the high quality weapons that were well cared for. The cheaper stuff broke but nobody was surprised (well apart from the unlucky soldier using it at the time) and they got melted down for scrap. If you’re an aspiring baron / daimyo with a retinue to equip and the local armourer can give you a hundred cheap swords in three months, or one triple quenched thousand folded katana that you can hand down to your grand children in three months, which choice wins you battles?

      1. I was curious about Chinese cannon history recently, and found pages saying that China didn’t develop heavy cannon because their city walls were already cannon-proof. 30-60 feet thicknesses of rammed earth, able to give even 20th century high-explosive artillery a hard time. In Europe there was a feasible arms race between cannon and fortification, in China the forts had accidentally already won.

        1. That’s not quite the case: The Ming and early Qing were quite interested in european cannon, and there were even attempts by the Ming to hire experts to build european-style Star forts. It’s just that well, the dynasty collapsed before anything came of that.

        2. This is one of the arguments laid out in the book “The Gunpowder Age”. Gunpowder weaponry in China was developed as an anti-personnel weapon and not an anti-fortification weapon due to the fact that wall breaches are uncommon in Chinese siege warfare due to the thickness of their walls.

      2. My understanding is that while japanese quickly adopted matchlocks and produced excellent pieces, they were slower and not as quick to adopt cannons (partially because of the construction reasons)

        my understanding is also that japanese castles weren’t designed against cannonfire but *were* designed to withstand wearthquakes (at least to some extent) and that accidentally ended up working pretty well against cannon, too.

  26. In the intro, “Last week” should be replaced – I imagine you started writing it a week after part 2.

    More to the point: I read somewhere, I forget where, that one of the reasons the motte and bailey evolved into the more familiar curtain wall castle is that the bailey’s palisade can be used to fortify against the motte. Moving the keep to within the curtain wall means that attackers who’ve taken the bailey-equivalent can’t fortify themselves this way. Is this correct? If so, does this mean that an attacker can take a motte in two steps, first taking the bailey and then after having had a night to sleep and plan the second step assaulting the keep?

  27. Somewhat off-topic: What do you think about the view that 18th-century European warfare was an unusually civilized affair? Did the cabinet wars truly feature officers who were so chivalrous (to their kind) that the prevailing notions of honorable conduct impeded military success? Were civilians noticeably better off than during the age of Napoleon?

    1. Look up the cost to Germany and Bohemia of the Seven Years War, or The Great Northern War impact on Finland. The officer class was multinational and sorted by religion was well as national allegiance (eg a lot of Huguenot officers in the British service, Irish in the French and Spanish, German in the Russian) and some concern not to repeat the Thirty Years War. But war still ate up the countryside, wrecked towns and spread disease.

    2. My 2-¢ is that the belligerents had a mutual desire to distinguish war from brigandage (and at sea, piracy) so that the losers were not summarily hanged or massacred. Hence the formalization of declarations of war and of obeying assumed codes of conduct.

  28. On citadels in towns: Hmm, I’m not sure if it was different in earlier eras, but if we leap back to the Hellenistic Era, there’s an interesting example of this in the Maccabean Revolt against the Seleucid Empire. The Seleucids apparently built a citadel either in or right next to Jerusalem, the Acra, and staffed it with Greek settlers & Greek-friendly Jews. Jerusalem later fell to the Maccabees, but the Acra didn’t. It was besieged once or twice, but relieved, and generally seems to have been able to gather supplies and send messages back to Antioch just fine. So apparently there was some sort of West Berlin / East Berlin split city situation for thirty years or so (170-141 BC), all thanks to this citadel. It seems like it was substantially more useful than merely buying time for more negotiations – was this because warfare changed by the Middle Ages, or just an exception that proves the rule?

  29. > Consequently, for most castles the greatest threat remained escalade, followed by treachery or starvation, followed by sapping, followed by artillery.

    It sounds like the chief weapon is surprise, fear and surprise, …

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