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This week we’re going to look at everyone’s favorite kind of armored fighting vehicle, the tank. In part this is a response to my frustration – one shared by, it seems, quite a few people – at the continued inability for journalists in particular to correctly identify what is and is not a tank. But more importantly it provides an opportunity to discuss what tanks are and what they are for.
This isn’t going to be a real ‘deep dive’ into the development and design of armored fighting vehicles as that is a huge topic. Rather this is going to be a brief overview of how we got both tanks but also other tank-like objects which often get mistaken for tanks with some particular attention to what these various vehicles are for: what their role is and how that dictates elements of their design.
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Defining a Tank
Whenever this topic comes up, someone swiftly produces some version of this chart:
Or this somewhat more fanciful version:
So what defines a tank? If I was pressed for a hard definition, I’d say that a tank is a heavily armored and tracked combat vehicle whose purpose is to offer powerful direct fire capabilities against a range of enemy targets. This isn’t quite a doctrine-only definition, but it is certainly a doctrine-first definition; the technical details (heavy armor, tracks) actually both relate to the specific capabilities they provide (which we’ll get to in a moment).
But in practice, like many weapons and weapon-systems, the tank and its definition is rooted in its developmental history and the problems that tanks were created to solve. So…
Where Did the Tank Come From and Why?
We’ve actually already discussed this to a degree: the tank was a direct response to the battlefield conditions of WWI, in particular the trench stalemate on the Western front. The idea of some kind of armored ‘land cruiser’ (potentially armed with machine guns) had been floated before WWI but never seriously considered and developed on, but serious development only began in 1915 with the formation of the Landship Committee early that year. Famously, they needed a code-name for their planned vehicle and opted first for ‘water carrier’ and then for ‘tank,’ thus giving the tank its peculiar English name.
And we should stop to note that as with any question of definition, this one too is language-sensitive. The exact confines of a term vary from one language to another; kampfpanzer, for instance is not necessarily an exact synonym for ‘tank.’
In any event, the basic demands of early tanks were dictated by the realities of the Western Front: a tank needed to be able to resist small arms fire (particularly machine guns), deliver direct supporting fire itself, it needed to be able to move on the muddy, artillery-flattened ground and it needed to be able to cross a trench. This last requirement – the need to be able to both climb a parapet (usually c. 4ft) and then cross over an 8ft wide trench – was significant in the design of early tanks.
Those factors in turn dictated a lot of the design of early tanks. The armor demands of resisting small armies fire meant that the vehicle would be heavy (and indeed, as soon as tanks appeared amongst Allied troops, their German opponents began introducing more powerful bullets, like the K bullet and later the 13.2mm anti-tank round fired from the Mauser 1918 T-Gewehr). And here is the first advantage of tracks. The weight of a vehicle is distributed along all of the area of contact it has with the ground; with tires that area is limited to the bottom of the tire so the total area of ground contact is fairly low, which is fine for most vehicles.
But tanks are heavy. Really heavy. Even something like the Renault FT could mass around 7 tons and by later standards that would be classified as a tankette (a ‘mini-tank’ as it were); by WWII, medium tanks often clocked in around 30 tons. If you put a vehicle like that on tires, you are going to create a LOT of pressure on those small points of contact. That might still be OK if you are just going to drive on roads and other firm surfaces which can take the pressure. But remember: tanks were designed for the Western Front, which looks like this:
Fortunately for the landship committee, this wasn’t a new problem: farming tractors were also heavy and also had to operate in churned up (in this case, plowed) soft soil; the heaviest of these vehicles had much the same problem and the solution was continuous tracks or ‘treads.‘ When kept properly tensioned – tune in, by the by, to Nicholas ‘The Chieftain’ Moran’s YouTube for more than you ever want to know about track tension – the track distributes the weight of the tank across the entire section of the track touching the ground, which reduces the ground pressure at any given point, allowing a big heavy tank to roll over terrain where even a much lighter wheeled vehicle would get stuck.
This is one of those points where the functionality of a tank (what a tank does) has such a strong influence on design that the design implications of the functionality become part of the definition: a tank has to be heavily armored and has to be able to move off road and as a result has to be tracked, not wheeled. One might be able to imagine some sort of exotic technology that might make it possible to do all of the things a tank does without tracks, but we don’t have that yet.
The other factor was fire. I’ve mentioned this before, but one of the significant background factors of WWI is that a lot of the belligerents misjudged the kind of artillery they’d need for a general European war. Not to get too deep into the weeds here, but most of the belligerents expected a relatively rapid war of maneuver and so thought that light, direct-fire1 artillery like the famed French ’75 (the Matériel de 75mm Mle 1897) would be the most useful. Those guns could be moved quickly and could deliver a lot of quick firepower on static or moving formations of enemy infantry in support of friendly infantry.
The problem is that in the conditions of trench warfare, those guns – as they were configured, at least – were far less useful. They were, first off, much shorter in range which meant they had to be brought dangerously far forward to do their direct fire role – often so far forward they could be engaged by enemy rifles and machine guns. This was compounded by the fact that direct fire at range was ineffective against trench works (which are dug down into the earth). But at the same time, the value of rapid firing (because these lighter guns could fire a lot faster than the heavy, indirect fire artillery) direct fire artillery remained high, if only you could get it to the fight.
This was also a problem a tank could solve: as a mobile, armored platform it could move a rapid-firing direct fire gun forward without immediately being knocked out by enemy small arms to support the infantry. There is, I should note, early complexity on this point, with both ‘male’ (heavy direct fire cannon focused) and ‘female’ (machine gun focused) tanks in WWI though in the end ‘hermaphrodite’ designs with both capabilities (but much more focus on the main cannon) triumph, so that’s what we’ll focus on.
And that gets us the fundamental role structure for tanks: enough armor to resist enemy small arms (but with the understanding that some weapons will always be effective against the tank), enough mobility to cross the churned up battlefield and some direct fire capability to support the infantry crossing it at the same time.
Comes the Halftrack
The period between WWI and WWII – the ‘interwar’ period – was a period of broad experimentation with tank design and so by the time we get to WWII there are a number of sub-groupings of tanks. Tanks could be defined by weight or by function. The main issue in both cases was the essential tradeoff between speed, firepower and armor: the heavier you made the armor and the gun2 the heavier and thus slower the tank was. The British thus divided their tank designs between ‘cruiser tanks’ which were faster but lighter and intended to replace cavalry while the ‘infantry tanks’ were intended to do the role that WWI tanks largely had in supporting infantry advances. Other armies divided their tanks between ‘light,’ ‘medium,’ and ‘heavy’ tanks (along with the often designed but rarely deployed ‘super heavy’ tanks).
What drove the differences in tank development between countries were differences between how each of those countries imagined using their tanks, that is differences in tank doctrine. Now we should be clear here that there were some fundamental commonalities between the major schools of tank thinking: in just about all cases tanks were supposed to support infantry in the offensive by providing armor and direct fire support, including knocking out enemy tanks. Where doctrine differed is exactly how that would be accomplished: France’s doctrine of ‘Methodical Battle’ generally envisaged tanks moving at the speed of mostly foot infantry and being distributed fairly evenly throughout primarily infantry formations. That led to tanks that were fairly slow with limited range but heavily armored, often with just a one-man turret (which was a terrible idea, but the doctrine reasoned you wouldn’t need more in a slow-moving combat environment). Of course this worked poorly in the event.
More successful maneuver warfare doctrines recognized that the tank needed infantry to perform its intended function (it has to have infantry to support) but that tanks could now move fast enough and coordinate well enough (with radios) that any supporting arms like infantry or artillery needed to move a lot faster than walking speed to keep up. Both German ‘maneuver warfare’ (Bewegungskrieg) and Soviet ‘Deep Operations’ (or ‘Deep Battle’) doctrine saw the value in concentrating their tanks into powerful striking formations that could punch hard and move fast. But tanks alone are very vulnerable and in any event to attack effectively they need things like artillery support or anti-air protection. So it was necessary to find ways to allow those arms to keep up with the tanks (and indeed, a ‘Panzer divsion’ is not only or even mostly made up of tanks!).
At the most basic level, one could simply put the infantry on trucks or other converted unarmored civilian vehicles, making ‘motorized’ infantry, but as discussed a whole part of the design of tanks is to allow them to go places that conventional civilian vehicles designed for roads cannot and in any event an unarmored truck is a large, vulnerable tempting target on the battlefield.
The result is the steady emergence of what are sometimes jokingly called ‘battle taxis’ – specialized armored vehicles designed to allow the infantry to keep up with the tanks so that they can continue to be mutually supporting, while being more off-road capable and less vulnerable than a truck. In WWII, these sorts of vehicles were often ‘half-tracks’ – semi-armored, open-topped vehicles with tires on the front wheels and tracks for the back wheels, though the British ‘Universal Carrier’ was fully tracked. Crucially, while these half-tracks might mount a heavy machine gun for defense, providing fire support was not their job; being open-topped made them particularly vulnerable to air-bursting shells and while they were less vulnerable to fire than a truck, they weren’t invulnerable by any means. The intended use was to deposit infantry at the edge of the combat area, which they’d then move through on foot, not to drive straight through the fight.
The particular vulnerability of the open-top design led to the emergence of fully-enclosed armored personnel carriers almost immediately after WWII in the form of vehicles like the M75 Armored Infantry Vehicle (though the later M113 APC was eventually to be far more common) and the Soviet BTRs (“Bronetransporter” or “armored transport”), beginning with the BTR-40; Soviet BTRs tended to be wheeled whereas American APCs tend to be tracked, something that also goes for their IFVs (discussed below). These vehicles often look to a journalist or the lay observer like a tank, but they do not function like tanks.3 The M113 APC, for instance, has just about 1.7 inches of aluminum-alloy armor, compared to the almost four inches of much heavier steel armor on the contemporary M60 ‘Patton’ Tank. So while these vehicles are armored, they are not intended to stick in the fight and are vulnerable to much lighter munitions than contemporary tank would be.
At the same time, it wasn’t just the infantry that needed to be able to keep up: these powerful striking units (German Panzer divisions, Soviet mechanized corps or US armored divisions, etc.) needed to be able to also bring their heavy weaponry with them. At the start of WWII, artillery, anti-tank guns and anti-air artillery remained almost entirely ‘towed’ artillery – that is, it was pulled into position by a truck (or frequently in this period still by horses) and emplaced (‘unlimbered’) to be fired. Such systems couldn’t really keep up with the tanks they needed to support and so we see those weapons also get mechanized into self-propelled artillery and anti-air (and for some armies, tank destroyers, although the tank eventually usurps this role entirely).
Self-propelled platforms proved to have another advantage that became a lot more important over time: they could fire and then immediately reposition. Whereas a conventional howitzer has to be towed into position, unlimbered, set up, loaded, fired, then limbered again before it can move, something like the M7 Priest can drive itself into position, fire almost immediately and then immediately move. This maneuver, called ‘shoot-and-scoot’ (or, more boringly, ‘fire-and-displace’) enables artillery to avoid counter-battery fire (when an army tries to shut down enemy artillery by returning fire with its own artillery). As artillery got more accurate and especially with the advent of anti-artillery radars, being able to shoot-and-scoot became essential.
Now while self-propelled platforms were tracked (indeed, often using the same chassis as the tanks they supported), they’re not tanks. They’re designed primarily for indirect fire (there is, of course, a sidebar to be written here on German ‘assault guns’ – Sturmgeschütz – and their awkward place in this typology, but let’s keep it simple), that is firing at a high arc from long range where the shell practically falls on the target and thus are expected to be operating well behind the lines. Consequently, their armor is generally much thinner because they’re not designed to be tanks, but to play the same role that towed artillery (or anti-air, or rocket artillery, etc.) would have, only with more mobility.
So by the end of WWII, we have both tanks of various weight-classes, along with a number of tank-like objects (APCs, self-propelled artillery and anti-air) which are not tanks but are instead meant to allow their various arms to keep up with the tanks as part of a combined arms package.
MBTs and IFVs
As we get into the Cold War era, one thing becomes simpler: the distinction between different kinds of tanks (heavy, medium, light, cruiser, infantry, etc) largely4 drops away. Improved engines, suspension and lighter but more effective composite armor meant that the slightly different roles of the different weights of tank could increasingly be accomplished by a single platform evolving out of late-war medium tanks. You could now fit a heavy tank’s gun and armor on a chassis with a medium tank’s speed and maneuverability. The first of these ‘universal’ tanks was the British Centurion (first deployed in 1946)5 and other countries followed suit.
The result is the modern ‘main battle tank’ (MBT), typically between 45 and 75 tons, with a single powerful direct-fire cannon as its primary armament. That’s not to say design differences between militaries drop away; there are still decisions to be made: the level of emphasis between speed, armor and firepower for instance. Another major decision is whether a tank is designed with a three-person turret (one of whom is a dedicated loader) or a two-person turret with an autoloader (that is, a machine that does the loading for you). It used to be that now I’d have to go on about why going autoloaders aren’t simply obviously the best but given the live demonstrations of some of the drawbacks of Soviet/Russian carousel autoloaders going on right now I’ll just say that both options have advantages and drawbacks and move on. So there is variety within the idea of an MBT, but by and large most countries field just one type of MBT (or one family of MBTs for countries which can’t afford to retire older systems) and that covers their tank needs.
But of course nothing could easy so just as tanks were getting easier to keep track of, APCs get much more complicated. Even before they were fully enclosed, APCs had generally carried some kind of defensive weapon (usually a heavy machine gun), but you weren’t supposed to fight with it if you could avoid it. Beginning in the 1950s, designers – first in West Germany – began experimenting with the idea that an APC could be armed to not merely deliver the infantry (‘dismounts’) but to actually fight when they got there. The thing is, there are a lot of situations where an infantry formation might want more firepower but where a tank would be overkill: armored vehicles lighter than tanks, or enemies with lighter fortifications, for instance. West Germany pioneered the idea by putting a 20mm autocannon on their APC, the Schützenpanzer Lang HS.30, enabling it to put out some meaningful firepower, albeit much less than a tank.
The USSR cottoned on to the idea and liked it, resulting in the Soviet BMP-1 and the subsequent BMP family of what we call ‘infantry fighting vehicles’ (IFV). Initially resistant to the idea (American doctrine was that APCs move troops and should not fight if they could help it), the United States, noticing the effectiveness of these sorts of platforms, got into the act with the Bradley Fighting Vehicle (these days the M2 Bradley). And IFVs, especially the Bradley, look like tanks. And indeed, they are sometimes called on to do the kind of armored reconnaissance and infantry support jobs that in a previous era would have gone to a light tank.
But they are also notably not tanks in several key ways. The primary job of an IFV is to move infantry and support them against lighter targets; some IFVs do maintain some kind of anti-tank capability, but it tends to be more limited (e.g. the Bradley’s pair of TOW AT missiles). The requirement that an IFV needs to be fairly fast but also needs to fit a bunch of dismounts means they can’t carry the firepower or the armor of a tank, often using lighter aluminum armor rather than steel or heavy composites. Finally, the tendency is for IFVs to mount lighter primarily armaments – again, space and weight concerns – like the Bradley’s 25mm M242 Bushmaster chain gun. The BMP-3 is probably the most heavily armed IFV out there with a low-velocity 100mm rifled gun and a 30mm autocannon, which is still a far cry from the firepower of the high-velocity 125mm main gun of a contemporary T-80 or the 120mm high velocity gun of a M1A1 Abrams. Instead, most IFVs would rely on anti-tank missile systems to engage tanks (although IFV autocannons can cause a tank serious problems if they can engage the rear or side armor, which is thinner).
Note that the IFV did not mean the end of the APC just as the APC didn’t bring the end of soft-skinned troop transports. In the US military, the Bradley serves alongside lighter-but-still-IFV Strykers, the venerable M113 APC along with soft-skinned HMMWV (Humvees; to be in theory replaced with the Oshkosh6 L-ATV) and trucks of various kinds and uses. Likewise, the Russian army has its BMPs (which are IFVs), and BTRs (which are APCs) as well as soft-skinned vehicles – or at least it did until, I am now being told, they were all towed away by Ukrainian farmers. The real Iron Harvest.
The final category worth noting here are variations on the concept of the MRAP (Mine-Resistant, Ambush-Protected): infantry transport vehicles designed to resist the sort of dangers one encounters in counter-insurgency operations, mostly mines, IEDs and small-arms ambushes. In essence, these vehicles are a purpose-built version of the up-armored Humvees designed to operate in a very particular combat environment (insurgencies and particularly urban insurgencies). These sort of vehicles have gotten more visibility in the United States because many of them have been shifted into the hands of law enforcement, where their utility is questionable, to say the least.
So What is a Tank?
In many ways, the role a tank fills hasn’t changed much since WWII when ‘engage other tanks’ was added to its list of jobs: tanks provide offensive ‘punch’ and firepower to allow infantry to advance, seize ground and maneuver in an environment where, thanks to machine guns, even small enemy forces can put out a lot of bullets to otherwise prevent infantry from doing those things. Tanks also need to engage other armored vehicles and potentially fortified positions. Doing those two jobs require that tanks heave the heaviest armor and the heaviest main gun possible, which both precludes them doing other things (like moving infantry) while at the same time demanding that they be tracked in order to manage the weight of that stuff.
I don’t think a tank needs to have a turret, by this definition, to be a tank, but most tanks have turrets. But many non-tanks also have turrets. The key here is role and function, not any particular design element.
What has changed is that tanks have gone from being effectively the only armored vehicle on the battlefield to working in concert with many other armored fighting vehicles, which have different roles. IFVs, in particular, can blur the line a bit between a tank and an APC, but in most cases the differences in design, firepower and thus capabilities between a tank and an IFV is massive; attempting to use IFVs like tanks is a good way to lose a lot of IFVs.
Is the tank on the way out? I don’t think so. Nicholas ‘The Chieftain’ Moran did a fairly good overview of the question, but the key point here is that the design of the tank is dictated by its battlefield function and there still isn’t anything out there that does a tank’s job better than a tank does; IFVs and other AFVs have to make pretty clear compromises in armor protection and firepower to accomplish their main roles. And while the public may be discovering the vulnerability of the tank for the first time, tanks have always been vulnerable to a wide variety of threats and have always required supporting arms to mitigate (but not remove) that vulnerability.
Now does it matter that the general public cannot tell the difference between a tank and an IFV? No, it probably doesn’t, to be honest. But it does matter that journalists covering wars and politicians making decisions about them also don’t seem to be able to, because it hints at a broader gap in the base of knowledge they are working with. “Bradley/BMP-3 isn’t a tank, but something else (an IFV) with a different function and purpose” is a fairly entry-level piece of information about modern warfare. And at some points that information gap can be abused, as when the German ambassador to the United States described Germany sending ‘Gepard Tanks’ to Ukraine:
Presumably Emily Haber was attempting to avoid a truer description of the event which would have been, “Germany is sending largely obsolete self-propelled anti-air platforms, the Flakpanzer Gepard, to Ukraine.” A journalist who is actually qualified to be covering a modern conflict ought to immediately be able to call this out as, at best, an unfortunate mistake (if not an intentional error). But journalists often sadly lack that kind of domain-specific knowledge, which really hurts their ability to inform the public.
(Edit: It seems worth clearing up confusion here about the German word panzer. While it is often translated as ‘tank’ (and so Flakpanzer gets translated as ‘Flak-tank’ or ‘AA-tank’) that’s not really right. Panzer means ‘armor,’ thus kettenpanzer is the German word for mail armor (one of them, anyway), “chain armor” literally. The direct German equivalents for ‘tank’ are the older panzerkampfwagen (‘armored fighting vehicle’ but in use clearly means ‘tank’) or the more modern Kampfpanzer. Of course you can just use panzer in German to mean ‘tank’ just as in some cases you can use ‘armor’ in English to mean tank (“enemy armor, coming down the road!” means tanks, not a procession of breastplates). That said, this article was fundamentally about the usage in English where ‘tank’ is more narrowly defined than panzer is in German. Equipment terminology actually tends to be very language-specific in terms of what it includes and excludes.)
In any case, here is the terminology shorthand: any armored fighting vehicle is an ‘armored fighting vehicle’ (AFV – convenient, huh?); that includes tanks, but also self-propelled artillery and self-propelled anti-air, IFVs, MRAPs and APCs. A tank is an AFV whose purpose is to offer powerful direct fire capabilities against a range of enemy targets (infantry, buildings, other tanks and other AFVs); tracks, while not a dead giveaway are good to look for. Not all tracked AFVs are tanks, but all tanks are tracked AFVs because of the demands that the weight armor and firepower place on them. If you take an APC and put big gun on it, it becomes an IFV, not a tank. If you take a truck and put a big gun on it, it becomes a technical, not a tank (but that’s a story for another post).
This post is not a tank.
Edit: Turning the Post off and on again.
Edit2: For some further viewing if you want to know more about the development of armored fighting vehicles of all kinds, may I suggest the videos of Nicholas ‘The Chieftain’ Moran and Bernard Kast, the latter of whom has a channel, Military History Visualized. Both are great channels that I particularly like because they foreground their sources, be that surviving examples of equipment, academic literature or doctrine publications.
- That is, guns that fire in low arcs towards their targets. The opposite is indirect fire, where the projectile is shot mostly up to fall on the target.
- Technically here a major issue is also the size of the gun, since a larger gun means a bigger turret, which means a much heavier tank
- At least not against well-armed enemies. It is worth noting that, when fighting against enemies who lack access to effective heavy weapons and also don’t have any armored platforms of their own that would require something more powerful than a heavy machinegun, APCs could be used as a sort of ‘poor man’s tank.’
- With some exceptions
- You really feel for the British, whose tank designs during WWII often left a lot to be desired and it is only as the war is basically over that they stumble on one of the best tank designs ever in Centurion.