Fireside this week! We’re in the last few weeks of the semester, but semesters tend to ‘crescendo’ rather than ‘wind down’ so there has been a lot going on. I’ll probably be posting a gap week for next week (Friday, April 29) because I’ll be at the annual meeting of the Society for Military History in Fort Worth, TX. I’m not presenting this year, but I am chairing a panel on ‘Issues of Governance, War and Identity from Rome to Vietnam.’
For this week’s musing, I want to take on a bit of a lighter topic: the size of science fiction space armies (and to a lesser extent, fleets). It has long been observed that Sci-Fi writers have no sense of scale and that is certainly a fair observation. Indeed, when it comes to the size of armies, most writers seem to have little sense of scale, but in galaxy-spanning space operas one can be several orders of magnitude off of the correct scale. Nevertheless, I want to caveat some assumptions that various science fiction civilizations ought to have trillions of combat troops or many thousands of warships.
The first issue is what in military parlance is called the ‘tooth to tail’ ratio. This is the ratio of the number of actual combat troops (the ‘tooth’) to logistics and support personnel (the ‘tail’) in a fighting force. Note that these are individuals in the fighting force – the question of the supporting civilian economy is separate. The thing is, the tooth to tail ratio has tended to shift towards a longer tail over time, particular as warfare has become increasingly industrialized and technical.
The Roman legion, for instance, was essentially all tooth. While there was a designation for support troops, the immunes, so named because they were immune from having to do certain duties in camp, these fellows were still in the battle line when the legion fought. The immunes included engineers, catapult-operators, musicians, craftsmen, and other specialists. Of course legions were also followed around by civilian non-combatants – camp-followers, sutlers, etc. – but in the actual ranks, the ‘tail’ was minimal.
You can see much the same in the organization of medieval ‘lances,’ – units formed around a single knight. The Burgundian ‘lance’ of the late 1400s was composed of nine men, eight of which were combatants (the knight, a second horsemen, the coustillier, and then six support soldiers, three mounted and three on foot) and one, the page, was fully a non-combatant. A tooth-to-tail ratio of 8:1. That sort of ‘tooth-heavy’ setup is common in pre-industrial armies.
The industrial revolution changes a lot, as warfare begins to revolve as much around mobilizing firepower, typically in the form of mass artillery firepower as in mobilizing men. We rarely in our fiction focus on artillery, but modern warfare – that is warfare since around 1900 – is dominated by artillery and other forms of fires. Artillery, not tanks or machine guns, after all was the leading cause of combat death in both World Wars. Suddenly, instead of having each soldier carry perhaps 30-40kg of equipment and eat perhaps 1.5kg of food per day, the logistics concern is moving a 9-ton heavy field gun that might throw something like 14,000kg of shell per day during a barrage1, for multiple days on end. Suddenly, you need a lot more personnel moving shells than you need firing artillery.
As armies motorized after WWI and especially after WWII, this got even worse, as a unit of motorized or mechanized infantry needed a small army of mechanics and logistics personnel handling spare parts in order to stay motorized. Consequently, tooth-to-tail ratios plummeted, inverted and then kept going. In the US Army in WWI, the ratio was 1:2.6 (note that we’ve flipped the pre-industrial ratio, that’s 2.6 non-combat troops for every front line combat solider), by WWII it was 1:4.3 and by 2005 it was 1:8.1. Now I should note there’s also a lot of variance here too, particularly during the Cold War, but the general trend has been for this figure to continue increasing as more complex, expensive and high-tech weaponry is added to warfare, because all of that new kit demands technicians and mechanics to maintain and supply it.
Why do I think this is relevant to science fiction armies?
Because there’s no real reason to suppose that trend wouldn’t continue in most science fiction universes. First of, we’ve already gone over why I thin even in a spare-faring context, ground operations might not be dead letter at all. That said, an army structured for orbit-to-ground combat operations is going to have wild logistics demands, even if we assume lots of exotic technology solving things like, for instance, the prohibitive cost of getting military equipment to and from orbit. You’d be looking, at least, an army with armored and mechanized forces (since it needs to have a firepower advantage once it is on the ground against defenders) that needs to be air-droppable. In most cases, armies in science fiction appear to be almost entirely air mobile (e.g. the marines of Halo with their Pelican dropships or the Clone Army in the Star Wars prequels; both appear to be 100% air mobile, including armor), which in turn means fueling, repairing and operating a massive fleet of air mobility platforms both for your troops and also for heavy weaponry. Moving just the infantry component of a single infantry brigade combat team would, for instance, demand something like 300 of Halo’s Pelican dropships (or around 140 V-22 Ospreys if you want a modern platform with similar V/STOL capabilities).
That sort of configuration poses formidable logistics challenges, but it makes a degree of sense. The attacker in such a scenario has a huge mobility advantage already coming from orbit (ships in low orbit circle a planet very fast, enabling them to deorbit basically anywhere on very short notice), but would surrender that advantage if troops once landed couldn’t re-orbit or at least become air mobile quickly. On the flip side the defender is likely to have at least numerical parity if simply because they don’t need to fly through space to get to the battlefield. They also don’t need combat platforms which can be orbit-dropped, so they can employ literally heavier combat systems. Emphasizing mobility, airpower and orbital fires all seem like ways the attacker can level the playing field. But of course then you need to maintain all of that equipment, and stock all of that firepower, though you at least have the advantage that much the ‘tail’ can remain in orbit in space (avoiding the cost of both de-orbiting but also re-orbiting when the operation is done).
At the same time, another trend we’ve seen as the technological and industrial demands of war have increased is that the militarization rate – the percentage of individuals under arms when a country is at war – essentially peaked in WWII and has since declined. Part of this is the cost of the modern military kit: the most effective kinds of fighting are really expensive on a per-soldier basis and so the armies that use them have gotten smaller because a small number of modern-system units is more effective than a large number of static-system units, while at the same time you can only afford a smaller number of modern-system units because they’re so expensive. That has gone hand in hand with increasing dispersion in response to firepower: you need to spread out your systems because enemy firepower is so intense. That limits how many soldiers can operate on a given length of ‘front.’
Contrasting military operations in the Ukraine in WWII to military operations in Ukraine today actually displays some of these effects very clearly, especially when you keep in mind that the USSR of 1940 had a similar, but lower total population to the Russian Federation today (c. 110m to 140m). While neither side has truly ‘filled the frontage’ across the entire border, there is effectively continuous contact along a large front from Kharkiv through the Donbas, despite the forces involved being substantially smaller than the forces involved in the same area in WWII. The dispersion is much higher and thus the density of forces in combat is lower in order to try to avoid the tremendous firepower of the enemy. For cinematic reasons, science fiction shows and movies often show troops at extremely high densities (often closer to late 18th, early 19th century warfare), but in practice dispersion would limit the total number of troops that could be deployed over a given frontage.
In that context, while perhaps a Space Empire could mass-mobilize billions of troops, it’s not clear that they would do so, even in a war where planetary invasions were important combat operations. Instead, they might well assess that the better ‘bang for their buck’ would be a two-tier army: planetary defense forces as a jumbo-sized version of reserves/national guard/territorial defense units, supplemented by a much smaller, much more materiel intensive maneuver army designed for offensive operations like planetary invasions, with the latter soaking up much of the budget as its fancy high-tech systems were expensive to build and maintain.
Now that kind of maneuver army would still almost certainly be larger than what we see in most science fiction settings; probably low millions for a force that plans to be able to seize one planet at a time; much higher for a military that wants to be able to engage in multiple such operations at once. But it wouldn’t necessarily mean billions or trillions of soldiers, either in the tooth or the tail.
Meanwhile, of course, there is a second limiting factor here, which is the degree to which the state can actually access and organize productive resources. The armies of Dune are, for instance, fairly small. The invasion of Arrakis seems to have been done with just 11 ‘legions’ of 30,000 men each (330,000 total; one of these legion are of Sardaukar, the rest Harkonnen), which is not a lot given that it represents essentially a maximum effort by one of the strongest Great Houses in the Imperium. But then the social system of Dune, the faufreluches, doesn’t lend itself to total economic mobilization either. Social class is fairly rigid and inflexible. Meanwhile, a system based on personal hereditary rule and personal relationships (the kind where Dune‘s – the book, to be clear – banquet scene is a useful political exercise; think about what it means about social organization that the banquet is a better use of everyone’s time than mass politics) is going to struggle to mobilize meaningful resources on a planetary scale.
Likewise, the governments in Star Wars (both Republics and the Empire) clearly haven’t been able to extend anything like a modern administrative state over most of the galaxy. Lando is, after all, running a self-governing independent mining city and only gets noticed because his rebel friends get tailed there. Whole sections of the capital planet seem to exist effectively outside of the supervision of the central government and we regularly see planets that clearly exist outside of the meaningful reach of the central government. In short, the vastness of population and physical distance prevents those governments from creating the same kind of total economic and popular mobilizations that smaller states on Earth manage, which is going to limit their military capability. That’s not a crazy notion either; as empires grow larger, their ‘militarization rates’ tend to fall because new conquests cannot be administered as intensively as old ones, because they are culturally different and further away.
A good way of thinking about this is how the different military structures of the ancient Mediterranean (oriented around cities and towns with local civic governments) and much of the medieval Mediterranean (oriented around landed mounted military aristocrats and their retinues) meant that the ability of these societies to mobilize resources for war declined, with most medieval armies in the broader Mediterranean and Europe being substantially smaller than what those areas could produce in earlier centuries. It isn’t entirely silly for a science fiction author to posit that the difficulties in ruling vast expanses of states might enforce similar limits.
And of course all of this goes double for fleets, which are nothing but big, expensive materiel issues, especially when one keeps in mind how absurdly huge many space warships are. Tthe interior space of something like the Battlestar Galactica, for instance, is probably a few hundred times larger than the largest modern warships when calculating for volume or mass. A Star Destroyer is even somewhat bigger than that; one estimate suggests that an Imperial Star Destroyer might mass something like 50 million tons, 500 times the displacement of the world’s largest warships. Given that, in the broader lore, Star Destroyers have to be supported by other smaller, but still very large warships, I am actually not surprised that the Galactic Empire has only a limited number of these platforms and can only concentrate a much smaller number in a single place.
All of which is to say that while I’d expect Future Space Armies to be very large, I don’t think you can cleanly extrapolate from the size of armies in WWII to get to the frontline combat strength of Future Space Armies: the tail is going to be much, much longer and the demands of logistics and resource mobilization may also sharply limit the degree to which a population can be militarized. A lot depends on the sort of society being posited here.
On to recommendations!
Over at Peopling the Past, for April they’ve been focusing on the study of human migration. Megan Daniels offers a historiography (the ‘history of the history’) of how archaeology has been used to study human movements and the shaping assumptions that have often been imported into that study. Catherine Cameron discusses her research on “Unwilling Migrants,” human migration through capture and captivity in the Americas; though I will note that while Cameron describes it as ‘astonishing” to find that most captives were women and children this is actually a very typical pattern in raiding both because adult males are the most able to escape a raid but even moreso because the adult males are killed rather than taken captive.
Meanwhile, Paul Johstono and Michael Taylor recently published a reassessment of the Battle of Pydna (168), the battle that effectively ended the Macedonian kingdom and secured Roman hegemony over Greece, in the journal of Greek, Roman and Byzantine Studies, which is gloriously open-access. Pydna is a tough battle to get to grips with as our sources for it are less than ideal: Livy would normally be a reliable source (deriving most of his details from the text of Polybius, lost for these years) but the surviving corpus of Livy cuts out for much of the early battle; Plutarch offers a complete narrative but much shorter and also less reliable. The source difficulties make a detailed effort in reconstruction like this valuable and well worth a read. If you do look at this, be sure to note the maps at the end, which do a lot to make sense of how the reconstruction is proceeding.
Events in Ukraine continue to show the primary of logistics in war and I’d be remiss, as the ‘orc logistics guy‘ if I didn’t point some of this out. Emily Ferris in Foreign Policy notes that “Russia’s Military Has a Railroad Problem,” a discussion of Russia’s logistics issues stretching from its reliance on rail logistics, which of course will be a familiar problem for those that read last December’s reading recommendation, Alex Vershinin’s “Feeding the Bear: A Closer Look at Russian Army Logistics and the Fait Accompli,” which seems to have largely correctly called the degree to which Russian ground forces would struggle to maintain their logistics beyond the railheads.
This week’s book recommendation is T. Sheppard, Commanding Petty Despots: The American Navy in the New Republic (2022), a history of the early formation of the senior officer corps for the US Navy from 1775 to 1824. The focus of the book is on how the often free-wheeling and startlingly glory-seeking command ethos of the early navy was reformed, albeit in degrees, into an organizational culture which valued professionalism and civilian supremacy over the navy.
Sheppard doesn’t treat this question in abstraction, but rather as a series of concrete narratives following the actions and careers of a progression of navy secretaries and captains. That both serves to make the book very readable – there are no problems with jargon here and the often colorful antics of some of these captains makes for entertaining reading – but it is also a good study into how a succession of leaders can shape organizational culture. Because of the slow communications of the period, the interaction between the ‘petty despots’ (the captains) of the title and the Secretaries of the Navy takes a sort of ‘call and response’ cadence: captains go out and do something and then the Secretary of the Navy has to respond later when they find out; they can’t micromanage their petty despots. Nevertheless, the long series of these calls-and-responses, especially after 1815, slowly established expectations for what command decisions and attitudes would be acceptable and what wouldn’t be. The shift in organizational culture is thus not examined in the abstract, but as a series of concrete decisions: who to praise, who to critique, who to promote, who to cashier, which collectively produce those abstract outcomes.
I find that particularly valuable: there is a tendency to treat questions of command ethos and organizational culture in broad abstract terms, especially when writing for a general reader. That can make sense in a lot of contexts, but it can also make it difficult to understand in a concrete sense what is actually being done to shape or change that organizational culture, to the point that organizational culture can seem impossible to shape or reform. What Sheppard demonstrates is how those ongoing ‘negotiations’ between Secretaries of the Navy, the eventual Navy Board and naval officers themselves steadily shaped and formed a more restrained, deferential and professional naval officer ethos.