Tank

" Remember Comrades, we are tank!
They take out treads, we are artillery!
They take out main gun, we are pillbox!
They take out machine gun, we are bunker!
They take out armor, we are heroes! "

– A popular internet copypasta about a tank's various roles in a nutshell

Were you looking for the MMO role that gets applied to tabletop games? If so, we have that under Combat roles

A French Renault FT-17 Tank, the first tank to have the rough layout that would be the norm for tanks (Crew in the front, top mounted 360 degree turret for main gun, engine in back)

A tank is a tracked, armored combat vehicle. The term is often limited to vehicles intended for direct combat, (e.g. as opposed to self-propelled artillery, which stay to the rear) or armored personnel carriers and infantry fighting vehicles, which are on the front line but are primarily tasked with carrying soldiers as opposed to fighting directly, and may not necessarily be tracked. Their invention revolutionized warfare in the 20th century, and any wargame set in or after that time period, or in alternate universes with similar or more advanced technology levels, will have plenty of attention devoted to them -- or to whatever made them obsolete (e.g. BattleTech).

The idea of an armored fighting vehicle dates back at least to Leonardo da Vinci and was explored by H. G. Wells and a few theorists, but the modern tank was proposed shortly before World War I, and was then spurred to production by the war itself. When the war on the Western Front got bogged down in trenches, the British Royal Navy, who had already had some success with mobile armoured car groups, had the idea to use tracked, armored vehicles with guns to break the stalemate. The name "tank" became attached to the vehicle as a codename to disguise the purpose of the large metal bodies being built. After the first tanks rolled onto the battlefield, other countries called them "battle wagons", "armors", "assault vehicles", and other more descriptive names, but the Anglosphere was stuck with calling them "tanks". (Interestingly, the original British Tank, which looked like a tractor with a metal box on top of it was called "Little Willy".)

Common Features of the Tank

Tanks were built with pretty much any set of features you could imagine, but over time, the militaries of the world settled on several key features:

1. A large-caliber cannon for destroying enemy targets.
2. A turret to house the tank gun, to allow the tank to shoot at targets without having to pivot the entire vehicle.
3. Good protection against most battlefield weapons, with a heavily-armoured front face to defeat anti-tank weapons
4. A multifuel engine with a lot of torque and horsepower.
5. Tracks with independent long-travel suspension for each roadwheel.
6. A radio!

Basically, tanks boil down to three main features: firepower, defence, and mobility. Trying to specialize in one or two attributes tended to come at the expense of second or third attributes. The heavier your guns and/or armour, the slower the tank will be, for instance, while a vehicle made for mobility has to sacrifice either protection or the size of its guns. Nowadays, tanks designers try to maximize all three attributes by being cleverer about achieving their goals, with their main limitations being weight and profile. Additionally, a fourth factor to consider in design are support systems: while not necessarily integral to the design of a tank, they are nonetheless essential in allowing it to work as one, as evidenced by the radio.

Offense

One of the defining attributes of the modern tank is its main gun, though this was not always the case. The first tanks didn't really have a primary armament, but were bristling with guns. Initially, side-mounted sponsons were adopted for carrying armament because they could clear aim downwards into trenches. Obviously, as soon as trenches fell out of favour, so too did sponsons. Additionally, as an enemy tank will never be in said trench, mounting an anti-tank weapon in the sponson is utterly retarded. The French had this one figured out by 1918, adopting a turret in carrying the main armament of the tank, and some tanks developed during the interwar period actually had more than one (though this proved impractical).

Even after turrets became more common, tanks didn't necessarily have a primary weapon, for reasons that have much to do with technological limitations as designers not really being decided on the whole tank thing. The French Char B1 for instance, mounted a 47mm gun in the turret as a main anti-tank weapon, with a 75mm howitzer in the hull providing decent high-explosive shell capability. For a time, there was also a fad with the land battleship concept, whereby a tank would have multiple turrets each with their own weapon, the idea being that the tank could attack in all directions. In practice, this led to horribly oversized tanks that were less efficient than simply building more tanks with the same armament. Most eventually followed the German example of having one main gun and at most three machine guns as secondary armament, though they accepted that they might have to compromise in either anti-armor or anti-infantry roles, as demonstrated by the early Pz III/IVs. It wasn't until the T-34, with its 76mm gun, that people began to fully embrace the idea that it was possible to have a tank gun be capable of tackling armour and blowing stuff up with explosive shells.

Curiously, while tanks began to coalesce around the turreted concept, many remained turretless and as the German Stug proves, were successful weapons in their own right. The lack of a turret does have some advantages thanks to how it lowers overall profile and allow for a larger gun to be mounted than could otherwise be the case. That said, a turret-less tank is only really useful if you don't have the money to make a turreted tank, don't have a bigger tank for your bigger gun, and will only be fighting on the defensive. The latter is the reason why the only guys ever serious about turretless tanks after WWII were the Swedes with their Stridsvagen 103, and the Germans, with their Kanonenjagdpanzer 90.

Guns just got bigger and better from thereon. Starting with the Soviet T-62, they started to go from rifled to smoothbore guns. If you are in any way familiar with the development of gunpowder weapons, this may seem like a baffling decision, but there is a good reason. Anti-tank shot went from a simple lump of steel to sub-calibre munitions like APCR and APDS, as detailed on the cannon page. These essentially try to be better at penetrating by focusing more energy on a smaller area. A later development was APFSDS, the famous "Silver Bullet" or arrow-like penetrators which turned Saddam's tanks into ooey gooey explody Swiss cheesey. Likewise, they also started using HEAT shells, which are designed to use the power of a focused explosion to bore their way through armour; at one point, they were so effective that tanks were designed specifically around their use. Both of these munitions types actually suffered from the rotational forces imparted by a rifled barrel. For APCR, APDS, and APFSDS, rifling does not stabilize subcalibre rounds nearly as well; likewise, the shaped charge jet from HEAT shells doesn't hold together as well if it's spinning itself apart. The main exception was HESH, which was essentially a shell full of plastic explosive that flattens itself against targets; upon detonation, it creates a shockwave that is transmitted through the material, causing it to break and shatter if concrete, or to spall off into deadly shrapnel if steel. The spin imparted by rifled barrels helps the explosive pat out more evenly, hence why it is still commonly used by the Brits in their tanks.

Nowadays most tanks are armed a cannon with a calibre between 100mm to 125mm. Said gun must be capable of firing a wide range of different projectile types: at the bare minimum, it should have ammunition specialized for dealing with hard targets such as opposing tanks, or soft targets such as infantry. During the 1960s, there was an attempt to replace the gun with a missile or gun-missile system which... didn't quite pan out. The main problem is that to accommodate guidance systems, fuel, and all that jazz, missiles are a lot larger than an equivalent tank shell, which strictly limits the amount of ammunition that can be carried. Furthermore, limitations associated with the technology at the time (heavy and fragile hardware, minimum firing ranges) precluded their use on tanks. Future vehicles may carry railguns instead, pending the development of a sufficiently capable, lightweight power system.

In addition to the main gun, you also have the following weapons:

• Machine guns They've been around since the beginning, in some cases serving as primary weapons, and they're still around as secondary weapons on most armoured vehicles. They can be mounted pretty much anywhere: on the front of the hull, in its own turret on the hull, in the commander's cupola, on the side of the hull, on the back of the turret, beside the cannon (coaxial), or on top of the turret next to the hatch. The latter two are preferred for modern tanks: the coaxial can easily be used by the loader or gunner without having to change stations, and the top-mounted gun can be aimed pretty much anywhere around the tank, including at aircraft.

• Autocannons The next step up from machine guns. Like machine guns, they've also served on primary weapons on more than a few tanks. After the Second World War however, they've tended to be relegated to the status of secondary armament, with potential use against light armoured vehicles and helicopters. Despite their obvious firepower advantages, most tanks don't have them, on account of being rather cumbersome and requiring a separate ammunition supply. The only places where you could feasibly mount them are coaxially alongside the main gun like the French AMX-30; otherwise, you'd have to create a separate compartment somewhere on the turret or hull, as was done with the experimental MBT-70, which had a retractable cupola for it.

• Grenade launchers While tank cannons may fire high explosive shells of greater potency, an automatic grenade launcher has similar flexibility to a machine gun in urban environments, only with more firepower. Another form of grenade launcher is the smoke projector that many tanks incorporate as a defensive measure, but that's for later discussion.

• Mortar Like the grenade launcher, a mortar on a tank can be handy for fire support. The Aussies took a page from the Germans' "mad genius" book and mounted a 7-rounds 178mm spigot mortar on the back of a Matilda II tank, the idea being to give their infantry support tanks some serious close-range firepower for those cases something needed to be softened before an assault. That said, it didn't really take off: there were much more efficient ways of providing fire support separate from a tank, and the only reason it was worth bothering with was because many early-war British tanks of that period (like the Matilda) had extremely poor or even non-existent high-explosive shell capability. Nowadays, the only tank to feature a mortar is the Merkava, which largely serves as a utility weapon for firing special munitions such as smoke or illumination rounds.

• Rockets During the Second World War, a lot of countries experimented with mounting rockets on tanks, ranging from the various German Nebelwerfer attachments or the Calliope mounted on the American M4 Sherman. Like with the example of the Matilda II above, the point was to provide fire support in anticipation of an assault, or otherwise simply reuse obsolete tanks. They fell by the wayside for similar reasons.

• Guided missiles While attempts to use guided missiles as primary armament in tanks have largely failed to succeed (with one exception), they are still being developed as a special munition designed to be launched out of the main gun. This provides tanks with an option to engage targets that are difficult to hit at distance with their main gun, which can include helicopters. Lighter tanks like the M551 Sheridan typically use guided missiles to give them an extra anti-armor punch when needed. Similarly, old Soviet tanks like the T55AM2 are upgraded to fire advanced missiles as a way of extracting more usage from obsolete but otherwise functional equipment.

Defense

In general, tanks are designed to maximize their protection for a given weight. Initially, the only criteria during World War I was that tanks should be bulletproof... which they were, to some extent. While their armour might have been thick enough to deflect most bullets, poor quality steel and riveted construction meant that tank crew tended to get injured anyways by pieces of steel breaking off from repeated impacts. They also did jack squat against artillery, large bundles of grenades, poison gas, and flamethrowers; later in the war, the Germans developed special armour-piercing bullets and anti-tank rifles that could punch straight through.

Fast forward to the Second World War. Early on, you still had tanks that were so poorly armoured that they could be easily pierced in several places by heavy machine gun fire or special anti-tank rifles. As tanks got bigger and more capable however, they started to incorporate not only thicker, welded armour, but also a technique known as sloping. Basically, what this involved is the angling of armour plates to increase their line of sight thickness, so a 45mm plate angled at 45 degrees relative to an incoming shot would effectively have a thickness of 90mm. This technique was not unknown before the war, but the size limitations of earlier tanks made it difficult to implement, as sloped armour ate into usable interior space; it was also a little harder to build than just slapping everything together at right angles. Of course, then the T-34 came along and showed that sloping could make plates of even modest thickness repel any early or pre-war anti-tank weapon, and then on sloping became an integral feature for almost all tanks.

All seemed fine and dandy until some assholes started knocking together something called a shaped charge onto lightweight launchers that a complete bunch of nutters could use to take out a tank, creating weapons like the American M1 Bazooka or the German Panzerfaust. At some point during the Cold War, the increasing effectiveness of shaped charge weaponry made some designers throw up their hands and give up on providing maximum protection to their tanks. If the thickest armor you can put on a tank is going to get penetrated anyway then your best bet is not to armor it at all and focus on maximizing speed and minimizing profile to make sure you don't get hit to begin with. The German Leopard 1 and French AMX-30 were designed according to this principle, when it seemed like it would be impossible to defend against new HEAT shells. Others kept experimenting, and by the 1970s, people developed measures to deal with them, starting with the well-known principle of spaced armour, and then moving on to quartz and ceramic plates.

Nowadays, most modern tanks have good protection all around from most weapons, with a particularly heavily-armoured turret and front to resist dedicated anti-armor weapons. Most modern tanks have some form or another of composite armour, which consists of layers upon layers of spaced steel plates, ceramic tiles, kevlar liners, and so forth. The idea is that by putting these various materials together, you can achieve greater protection against most things for far less weight than an equivalent protection level of steel, though it does become quite bulky. How these materials exactly work together is not entirely known to even the most pretentious armchair generals. All that can be said for sure is that they tend to focus on clever techniques to deflect and mitigate the energy behind attacks, as opposed to trying to stop them with the raw thickness of solid steel.

Below are a few devices and techniques utilized for defensive purposes:

• Smoke Dischargers The little pipes or beehive-like clusters you see on the turrets and hull of the tank are smoke launchers, which fire a single salvo of smoke grenades upon activation. You may find the idea of trying to hide a tank ridiculous, but a good tank commander will know how to use smoke to mask their movements in case they need to make a hasty retreat. However, they're also really, really good at fouling up enemy sensors (anywhere from optical to infrared) and guidance systems.

• Reactive Armor As per the name, they are designed to react to incoming projectiles. The most common form is what is known as Explosive Reactive Armor or ERA: essentially metal boxes with a small explosive charge sandwiched between two metal plates. When a sufficiently large projectile hits an ERA tile, it detonates, forcing the metal plates apart; this can disrupt a shaped charge jet before it has time to form. Later versions like the Russian Kontakt-5 and Relikt are capable of defending against APFSDS munitions by forcing the penetrator off course, dissipating its kinetic energy. In addition, there is also what is known as Non-Explosive Reactive Armour or NERA. Instead of an explosive charge, NERA incorporates an elastic material that is wedged between the two metal plates. Like ERA, it will react to attacks; however, instead of exploding, the sandwiched layer will expand, with similar effects on incoming projectiles to ERA. Compared to ERA, they have the distinct advantage of not exploding, which makes them safe to use around infantry, so they tend to be more like easily-replaceable armour tiles; modern-day composite armours may also incorporate them into their defence arrays to varying extent.

• Slat Armor Due to how shaped-charge rounds work, they need to detonate at the right distance of the armor to punch through it. Something as simple as a metal cage surrounding you can prevent the shaped charge from doing much damage by just making it go off early or warping the detonator upon impact, rendering it useless.

• Improvised Armor Just like its name says. During the Second World War, tank crew tried to bulk up armour with whatever they could find in the field. These can take the form of salvaged armor plates from other tanks and bedspring mattresses, or nothing more than basic materials like sandbags, wooden logs, or ooncrete. Ironically, many of these materials were probably worse than nothing: the added weight overstressed components and slowed down whatever tank they were mounted on. Moreover, due to defects in HEAT design at the time, they may have actually enhanced the effect of the warheads by causing them to detonate at the optimal distance, away from the tank's main hull.

• Active Protection System An active protection system is a device that shoots down or deflects incoming anti-armor projectiles. It takes two forms. The first is an electronics countermeasure system that detects incoming guided missiles and attempts to trick them into not hitting the tank, usually by messing with their guidance systems. The other type involves an active radar scanner linked together with a launcher or projectile weapon of some sort; when it detects an incoming projectile larger than a bullet, it calculates its incoming trajectory and then fires a projectile which destroys it mid-flight.

• Spaced Armor Spaced Armor is what it sounds like. Armor with a large gap. This gap helps dissipate the shaped charge. The most obvious examples are goofy-looking thin plates around a WWII German tank's turret and tracks (Schürzen or skirts). Although they were initially designed to deflect light AT guns and rifles, they may have had some effect against HEAT warheads, at least according to some people. Whatever was the case, it has been well-established that trying to force a shaped charge to travel through three feet of air will protect a tank far better than a foot of armour. Usually incorporated as one aspect of modern composite armour.

Mobility

Track design is also integral to the identity of a tank and are what allow it to move around without sinking into the ground. They are so good at their job that a tank imparts a lower weight per square inch on the surface than an automobile or a human foot. That said, they are a significant weakspot: they can break or slip off, leading to a complete loss of traction, and a stopped tank is a dead tank. Running the tracks over the top of the body is begging for a mobility kill, no matter how cool the British Mark I looked. (Though to be fair to the Mark I, it needed its high tracks to cross trenches, and since it came first, there weren't really any weapons that could specifically take advantage of its exposed tracks at the time.)

More than tracks, suspension is what allows tanks to travel easily over all terrain, absorbing all of the bumps and lumps. The earliest tanks did not have any suspension. By the Second World War however, you had vehicles using varying arrangemnet of helical and leaf springs to smooth things out a little. Most tanks now employ what is called torsion bar suspension, which translates the up-and-down movement of the roadwheel into a metal bar designed to resist twisting. A few newer models employ hydropneumatic suspension, which can be adjusted to cope with softer or harder terrain, as well as adding a few more degrees of elevation or depression for aiming the main gun.

Most tanks designed prior to the Second World War but after the First World War utilized the same engines as trucks and buses (cheap but underpowered), while a few settled on downrated airplane engines (lots of power but unreliable). At the start of the war, only the Germans dedicated engine production for military vehicles (which led to problems that we won't get into here) but it was the Soviets who would later take the cake, with the relatively lightweight yet powerful diesel Model V-2 in the T-34 (seeing a pattern here?) that would go onto to power almost all of their tanks. Most tanks nowadays go for diesels (fuel-efficient but with poor power-to-weight ratios) but a few use turbines (runs on nearly anything flammable, high power-to-weight ratio, but very thirsty), though in the interests of making warfare more environmentally friendly, we may eventually see tanks driven by electrical power and hydrogen-fuelled turbines.

Support

In addition to the essential three attributes of offence, defence, and mobility, tanks rely on a whole host of systems to be tanking, key among which comprise communications. It can not be overstated how important a radio became to tanks. Utterly essential for communicating with other tanks as well as whoever is in charge; having a radio determines whether or not a tank is a rolling pillbox or a decisive, mobile weapon of war. In both the battle for France and the early Operation Barbarossa the German tanks were outnumbered, under gunned and under armored compared to their opponents but thanks to their radios, they were able to outmaneuver the enemy and take them apart. Radios also became important inside tanks because, well, tanks are LOUD, and it's the only way for the crew to talk to each other without going hoarse yelling at each other. And it's not a joke: before the advent of intercom the commander often had to kick the driver on the left or right shoulder to indicate the direction he wanted him to turn because even yelling wasn't working with the ruckus of the moving tank. Soviet tank crews actually communicated mostly in kicks until well into 1943 because early Soviet radios were shit tier and tended to break in the first minute of every goddamn engagement.

Below are some additional systems that are not utterly essential, but nonetheless very desirable:

• Autoloader Basically a mechanism for automatically loading shells into the main gun, obviating the need for a laoder. This is less of an obvious decision than it would seem. For decades, human loaders were actually regarded as better than mechanical loaders because they were generally faster and better: most early autoloaders had to depress the gun to a minimum elevation before loading and had difficulty switching between different types of shells. An autoloader that is put out of action by mechanical failure or damage will either make the cannon more difficult to load by hand or at worst, render it entirely inoperable, requiring extensive repairs in order to be restored to fighting condition. Plus, as mentioned in the previous section, having a human loader lends versatility and redundancy to a tank crew, as the loader could function as an additional pair of eyes and hands whenever needed. Initially, the main advantage to automating the loading process was that you could afford to have one less crew member, thus reducing overall weight. Newer developments however, can easily match or surpass human loaders in terms of loading speed, with the additional benefit of never tiring.

• Stabilizer

• Fire Control System

• DetectionTanks have notoriously bad situational awareness, so people came up with solutions to improve it. The most basic instrument is of course, Eyeball Mk. I, initially relying on either vision slots, optical instruments such as periscopes, or the commander poking his head outside of the tank. In WWII, the Germans installed an armored cupola with vision slits atop the turret in order to improve the commander's sight while 'buttoned up'. Nowadays, you have an array of cameras and infrared/thermal imagers to give you a clearer picture of things.

• Remote Weapon Systems The pintle-mounted gun is great for clearing out and suppressing infantry because it can rotate 360 degrees and is at the top of the tank, so it has a bird's-eye view of the area. Unfortunately, popping your head out to shoot at people makes you a prime target for snipers. A solution for this is having the pintle gun be virtually controlled from the inside by a remote weapon system, so the gunner can still shoot at targets without threat of catching a bullet in the face the moment they peek out of the hatch. Granted the gun itself can still be shot, but it's a lot easier to replace a machine gun than a trained crewman. The aforementioned blurb regarding replacing the MG with grenade launchers also apply here.

• Automatic Fire Extinguisher Fire? No problem. Tap a button or just wait a few seconds, and in the Abram's case, Halon gas at 7% puts it out.

• Blowout Ammo Compartment A big problem in WW1 and 2 was tanks going up from the ammunition being detonated when hit (the remains of the crew would be... messy, to say the least. Frequently they would be buried all together in a matchbox). So we first came up with wet storage, which reduced and delayed such 'cooking off' tremendously. But since there was still some risk and with tanks costing more and more every generation, we invented blowouts for modern tanks. They're basically compartments that blow outwards when the ammunition is hit and begin to burn; they vent the bang away from the main body of the machine, thus saving the million dollar tank (and the squishy but almost equally expansive meatbags inside). Sure, the tank must retreat to restock ammo, a new storage bin and some tuning up; but it can still fight with a small repair... if your ammo storage compartment wasn't open the moment it was hit, that is, which is not unheard of, and had no HE or HEAT shells in it (the reason why M1 Abrams do not carry those).

Crewmen

Unlike a car or most combat airplanes, a tank isn't something that one person can fully operate alone (at least for today's standards). It is a large, complex machine that requires multiple people with specific tasks to keep it working. Never discount the importance of a well-trained crew, as they can be every bit as important as the selection of equipment. While technically feasible to operate a tank with only two people (a driver and a gunner, as was the case with the Renault FT), it’s much more practical to have more people per tank to divide the workload, especially since a successful tank battle is heavily determined by the time it takes to get off a successful shot. Early tanks were envisioned as 'landships' and had a crew of around ten men, but most tanks today have a crew of three or four, with some crewman having multiple duties to keep things as streamlined as possible.

• Commander The commander is the one who issues orders to all crewmen. Their main responsibilities for the tank are navigating for the driver, spotting targets for the gunner, and coordinating everyone to work as one well-oiled deathmachine. They're also the one who typically mans the hatch-mounted machine gun when needed. In modern times, they are also responsible for the radio.
• Driver Maneuvers the tank, but with a twist. Because the driver is typically near the bottom of the tank he only can see in front of him unless he sticks his head out of a hatch; his peripheral vision borders on the non-existent. Because of that, they have to rely on the commander for precise maneuvers when the tank is traveling at full speed. That said, it is still possible for a driver to maneuver the tank on his own (yay for vision slits and/or cameras). In modern times, they also double up as the crew's mechanic.
• Gunner Operates the tank's main cannon(s) and coaxial machine gun, again with a small twist. He's responsible for aiming the guns where they need to shoot and firing when appropriate. They can also double as a loader if one's not available. But because the gunsight is quite narrow they can only make fine adjustments on their own and so need the Commander to spot the target and give them the rough direction in which to point the gun in the first place for them to acquire it and blow it up. A tank typically only needs 1 gunner, but older models that have more than 1 main cannon (like the WW1 British Mark tanks) required a gunner for each gun.
• Loader Assists the gunner by loading the appropriate ammunition into the main gun. Loaders are less common in modern tanks due to rise of autoloaders these days, but older tanks needed them to perform efficiently and the extra man has advantages his own. These include helping in field repairs and helping fuel the tank up and in the Abrams' case manning a second pintle gun.
• Mechanic Responsible for fixing up the tank when it breaks down (well, the whole crew pitches in but he's the guy with the knowledge). In later years to ease space concerns; the driver typically doubles as the crew's mechanic.
• Radio Operator Operates the radio and relays any orders and communications with friendly forces to the commander. Due to advancements in radio technology; radio operators are no longer needed in modern tanks as the commander can do that on their own these days.

Types of Tanks

Whether it's real or fantasy, tanks are classified from their weight and/or armament profile. A modern catch all term for all purpose built and improvised combat vehicles, not necessarily tanks, is Armored Fighting Vehicle (AFV). Here are the common ones:

Not Actually Tanks

Despite having treads and a gun, the following vehicles are not considered tanks. The difference is that tanks are designed for frontline combat, while other vehicles with treads are designed to carry and support infantry (APC/IFV), bombard enemy positions with heavy artillery (SPGs), or act as general support weapon systems. Many of these vehicles are light enough to be deployed by aircraft, giving them an edge over tanks in response time to emerging threats. If it isn't a purpose built chassis, they are frequently based on the previous or current tank being used to simplify logistics.

• Armored Personnel Carrier APCs are light vehicles designed to carry infantry and not much else. They're usually given a heavy machine gun to support the infantry they're carrying into battle and to defend itself, and not much else. They're designed to protect against small arms fire, not tank shells. Unlike IFVs, APCs are not expected to fight on the front due to their lackluster protection and armaments. However, they're sometimes also amphibious, something that the vast majority of tanks are not, allowing for both seafront assaults and quick getaways down waterways. Don't expect anything bigger than a HMG (that being under 20mm, usually also under or equal to 15mm) and a grenade launcher. Very rarely a low caliber (20 to under 25mm) autocannon may be present. May have a couple ATGMs (Anti Tank Guided Missile) to surpress the enemy but it isn't designed to stay in a firefight, an APC is first and foremost a transport.

Examples: Rhino, M113, Namer (notably, it is based on the Merkava, an MBT, and has unusually tough armor)

• Self-propelled gun (SPG) Vehicles armed with artillery weapons designed to bomb the enemy back into the stone age, ranging from howitzers, mortars, or missile systems. Typically built similarly to tanks, but sacrifice armor for their heavy guns since in normal circumstances they should be too far away to get shot at directly. Not to mention that some artillery pieces have a minimum range where they can drop their payload; thus, the SPG needs to put some distance between them and their target so that they can be in effective range. The advantage to having such artillery on an actual vehicle rather than being stationary, is that counter-battery fire can threaten static guns, while mobile guns can safely get out of the danger zone once they've delivered their payload. Self-propelled guns typically carry a 150+mm Howitzer, much larger than what any proper tank would carry. While mobile rocket platforms such as the BM-21 Hail or MLRS are more popular than Self-propelled guns and are capable of absolutely soaking an area in rocket spam, the SPG has the advantage of being able to sustain fire for longer periods of time. Besides that, most SPGs can also depress the barrel enough to engage something directly which can be useful in some situations (avoiding collateral damage, for instance). Do note that standard operating procedure for SPGs is to leg it like a little bitch tactically redeploy if the enemy close on their position: even if they carry a big gun, they are not front-line capable vehicles. Direct engagement is avoided even if a huge shell will ruin a punk's day just fine. May have a machine gun or two just in case (and theoretical anti-air in older models), or an autocannon if the armed force is particularly passive aggresive and has money to blow on useless overkill.

Examples: Basilisk Artillery Gun, M109 Howitzer

• Self-propelled anti-aircraft gun (SPAAG) Tank-like vehicles armed with weaponry designed to shoot aircraft out of the sky to provide mobile anti-air cover. There are only three real ways to shoot a very fast moving aircraft out of the sky. First you can use as many rapid fire guns as you can to fill the air with as many bullets as you can and hope for one hit. Second, you can fire one big shell up into the air and at a certain height have it explode spraying shrapnel around it self to score the one hit you need, this are known as Anti Air Artillery, and are known in the English world by the name the Germans used during World War 2, flak. Both have been superseded by AA missiles which can track a target and put that shrapnel warhead closer to the target than just guess work and a slide rule can. Others use both guns and SAMs. As a sidenote, flak tanks (and half-tracks) equipped with heavy machine guns and small autocannons have a nasty reputation as being infantry trouncers as multiple barrels spewing lead at high speed will turn soft ground targets into mulch very quickly. Indeed, both the M19 MGMC and the M42 Duster were primarily used in this role despite having been envisioned as point-defense SPAAGs. That role had something of a heyday between WW2 and Vietnam, with the quad mount 50 cal M45's being nicknamed Kraut Mover and the twin 40mm's of the M42 being used to lumberjack VC hiding in treelines. Modern variants mostly have guided missiles and the BRRRRT variants are usually not mounted on tanks.

Examples: Hydra Flak Tank, ZSU 23-4 Shilka

• Infantry Fighting Vehicle Known as IFVs, these almost-tanks are capable of transporting infantry forces, while being armored and armed enough to be of support to the field, unlike light tanks. However, unlike true tanks, IFVs can't be expected to stand up to enemy armor. Modern IFV's can have anti tank missiles, but with their tin can armor, going toe to toe with a main battle tank is suicide and so it supports regular tanks or takes on enemy armor in emergencies. While APCs and IFV can share similar roles and armaments today, the main way to distinguish them is with their main gun: anything that has a main gun smaller than 25mm is classed as an APC, and anything higher is an IFV. IFVs are designed to stay and fight (though not toe to toe with enemy tanks) and act as direct fire support. Effectively, when comparing a squad with an IFV vs a squad with an APC, the later is an infantry squad with a transport, the former is a (light) tank that can dismount some of its crew.

Examples: Chimera, Razorback, BMP, M2 Bradley

• Armored Reconnaissance Vehicle In some ways they can be confused for IFVs in that these vehicles are similarly equipped and focus on mobility, and may even have limited troop capacities. But where they mainly differ is in doctrinal use: Armored Recon is mainly used to provide independent support to a recon team rather than support front-line troops. As such, troop carrying capacity isn't as necessary if it has any at all. See below the Infantry vs Cavalry Tank distinction as it can apply here as well, since modern cavalry units use such vehicles. Some IFV's share a base chasis with ARVs , those ARVs are usually called Cavalry Figthing Vehicles (CFV).

Examples: Salamander Reconnaissance Tank, LAV-25, M113 MRV, M3 Bradley

• Tank Destroyer Tank destroyers are specialist armor designed for one thing in mind: knocking out armor and not much else. Some are turreted, and some aren't. Most modern ones use guided missiles, all historical and some modern use cannons. What makes them not tanks is a matter of technicality. Tanks are designed for general military purpose (so useful for a range of tasks) while tank destroyers are for only one thing, destroying armor (especially on vehicles). After World War 2 we figured out that since tanks fought other tanks so often anyway tank destroyers don't really make sense so we upgraded the guns on regular tanks, while the role of “Light Anti-Armor Vehicle” was taken by ATGM carriers, which being mostly modified LAVs, have the ability to kill tanks while being very mobile and easy to transport. A handful of cannon-armed Tank Destroyers still exist, some tracked, others wheeled, but they're a rare breed. They tend to be considered for use with airborne troops in need of anti-armor capability (since a proper tank tends to be too heavy to airdrop) and for certain strategic mobility concerns.

Examples: Destroyer Tank Hunter, Leman Russ Vanquisher, M901 ITV

• Assault guns Similar to tank destroyers, assault guns differ in one important way: instead of an anti-tank gun, they're armed with a anti-building weapon, frequently a howitzer. These tended to be fairly big and fairly heavy compared to SPGs, because they're made to get in close to heavy fortifications. After World War 2 assault guns became light air-dropped weapons to support airborne troops if they encountered hard targets. They are comparatively very rare in modern orders of battle. Most that remain are in the Third World (usually WW2 Soviet vintage, they made a LOT of things).

Examples: Vindicator, Leman Russ Demolisher

Proper tanks

• Male/Female A very, Very, Very early design and designation of tank done only really during the first world war when the British were still trying to figure out how this whole tank thing worked. The difference is obvious, male tanks have cannons, and female tanks have only machine guns. In modern time however Gendering Tanks is completely obsolete since, almost by definition a tank has a cannon so making tanks without cannons is a rather silly. Nether the less you can point to a few very light tanks as being in the same vein as the British female tanks, but only if small caliber autocannons count as machine guns.

Examples: Land Raider Crusader and Phobos pattern (female and male respectively)

• Tankettes Less of a tank and more of an armored clown car with guns; these were in vogue for a while in the 1930s. They're essentially a one or two-person tank, armed with machine guns, flame throwers, or anti-tank rifles and not designed to move much faster than the infantry around them (except for the italians, whose cute lil' buggers could reach a respectable speed). They're generally made to act as mobile infantry support or anti-tank weapons. Needless to say, this idea didn't stick because when even a high-caliber machine gun (which WW2 was rife with) could penetrate the armor of the tank, making it useless in straight-up combat. Only the Japanese extensively used them during WW2, which made some sense as most of their combat theater is in jungles that would bog-down full-sized tanks (Plus their doctrine emphasized more on air and naval superiority, with them island-hopping during their conquests). Tankettes however, were still fielded in limited quantities after WW2 due to their light weight that allowed them to be safely air-dropped, mainly for non-front line use like tank destroyers, AA guns, and recon vehicles. The only tankette still in use is the German Sedan-sized Wiesel, an airdropped scout vehicle. In effect, the smallest of the tankettes with a crew of one were an attempt to make an individual soldier into a one man tank to allow them to support their comrades. Sounds familiar, doesn't it?

Examples: Sentinel (effectively)

• Light Tank These are lightly armored tanks that sacrifice armor and firepower for maneuverability. They are not meant to be front-line combat tanks, as their armaments are usually too underpowered to go against heavier vehicles, rather they're usually relegated to reconnaissance duties and infantry support. Light tanks would carry guns that ranged from 37mm-45mm, though some early German Panzers were only equipped with machineguns. Some modern equivalents serve as Scout Tanks which are usually capable of paradrops.

Examples: Siegfried, M551 Sheridan

• Heavy tank The big boys, armed with the biggest guns and the thickest armor. Heavy tanks are what you send to crack an enemy defensive line as they slowly (or not-so slowly, as German and American heavies could reach similar speeds as their mediums) rumbled forward, guns blazing, destroying anything in sight... Except eventually Medium tanks, which split the difference between light and heavy tanks having more firepower than the former and more mobility then the latter, are just more cost effective and Heavy tanks are not too much better than improved mediums, which evolved into the main battle tank. Some heavy tanks were actually variants of medium tanks with heavier armor and/or guns, most notably those of the M4 Sherman. Heavy tanks typically carried 88mm-120mm cannons.

Examples: Sicaran Battle Tank

• Main Battle Tank/Medium tank Medium tanks, which were generally made to carry guns close to a heavy with mobility not far off a light, evolved into main battle tanks. These would become the primary tank for modern nations by combining high speed, adequate armor and most of all a powerful gun. MBT's are not as heavy as we could theoretically make a tank (although modern advances like reactive armor plates, have allowed them to still be as survivable as true heavies, while springing for a modern heavy could make it theoretically unkillable in a slugging match but vulnerable to guided munitions) but their speed makes up for it and they act as the spearhead of an assault force designed to create and exploit a gap in enemy defenses to allow massed mechanized forces to rush though the gap. Interwar and early WWII mediums usually had 37mm or 50mm cannons. WWII era medium tanks carried 75mm-90mm cannons, first generation (basically optimised mediums that still had a few optimised heavies accompanying them), second gen and the very first gen 3 MBTs typically had 105mm guns, and second gen retrofits and proper third gens (the modern generation of tanks, with the very newest named 3+ or 4) generally have a minimum cannon size of 120 mm or so, with the Russians coming in with 125's that can fire ATGMs and Rheinmetall building 130mm guns to counter them (there was also a test variant of the M1 Abrams with a 140mm gun).

Examples: Leman Russ Battle Tank, M1 Abrams

• Infantry/Cavalry tank A British and French design doctrine, the theory for the design goes like this. Infantry tanks support infantry, (hence the name) and therefore they don't need to go fast and can carry heavy armor while their guns did not have to be terribly strong to support the infantry. However they were too slow to use the line breaks they created (a problem in World War 1) hence the need for the Calvary tank. Cavalry or cruiser tanks were much, much lighter and were designed to move fast and rush though a gap the Infantry tanks made but could not use and create havoc behind enemy lines cutting communication, destroying supplies, etc. The idea was sound, however technology advanced so that Cruiser tanks could have the armor of a infantry tank without the slowness, and infantry tanks could have the speed of the Cruiser's meaning the distinction became meaningless. Before World War II, Russia had a similar idea for three different types of tanks, a breakthrough tank acting as an infantry tank, one tactical breakthrough tank, and a 'fast tank' to exploit gaps. The Cavalry tank role has been pretty much taken over by airdropped armored vehicles such as IFVs or Tank Destroyers.

• Flame tank a tank (going from tankette to heavy, all types were used in WWII) with a werfer zat werf flammen instead of a big gun as main weapon. Only used in the 1920s-1950s as they were quickly rendered obsolete (it was more cost-effective and just as efficient to have standard tanks have a flamethrower as a coaxial gun), though incendiary weapons of various sorts are still used today, mainly in artillery roles. Typically unpopular with both forces using and opposing them for many reasons: the implications of this weapon were very harsh as the typical man-portable flamethrower has a range of 60 meters max (video games lied to ME?!) and their heavy mechanized versions could reach most of a quarter mile with their concentrated hydraulic spray of diesel fuel. Flame tanks were supposed to start with a "Wet fire", basically spraying the fuel without igniting it into bunkers or fortifications to get enemy units to realize just how hard they were fucked, really weren't protected from the coming blaze at all and in turn they would surrender before being cooked to death. Which a vast majority actually did when hosed with gasoline. The problem was that, due to either open fighting, soldiers that just wouldn't surrender or sadistic crews/commanders, the weapons were often fired outright the first time around to horrific physical and psychological impact on both sides - burning, screaming soldiers, the fumes making crews sick, thick diesel smoke inhalation or oxygen depletion asphyxiating those in poorly ventilated areas (especially caves in the Pacific Front) and the smell of burnt human flesh permanently seared in their minds meant that instant life derailing post-traumatic stress disorder was a very common side effect of witnessing a flame tank in action. Another was that flame tank crews that were captured were usually subjected to torture and summary revenge executions. In the end, flame tanks are remembered as a job nobody wanted to do, an enemy nobody wanted to face, a weapon that accomplished little that soldiers using the man-portable variety (which already had a bad rep' but was begrudgingly tolerated by soldiers as tactically necessary to avoid chemical warfare, nobody in their right mind wanted to clear caves out directly) could not do and pushed the propaganda and soldier's beliefs forward that the enemy truly were barbarians and made of evil, all pushed ahead because a Commissa -- I mean General far removed from the field said they were necessary. Real life Grimdark indeed.

Examples: L3/35 "Lanciafiamme", M3 "Satan", M4 "Crocodile", Flammpanzer III, Churchill Crocodile, Kliment Voroshilov model 8, OT-34, technically any tank with incendiary or thermobaric ammo

• Super Heavy Tank Superheavies were conceived in World War I, essentially using the term "landship" literally. Armed with giant cannon (sometimes multiple ones, and usually reserved for artillery or battleships) and armor plating so heavy, you'd mistake it for a fortress; they were meant to be the ultimate line breakers. While some prototypes were fleshed out, none (except for the French Char 2C, although it arrived too late to be used in WW1 and was obsolete in WW2) were put into service because they were simply too impractical. They were often too heavy to be supported by most roads (and off-road would have been worse), and were a logistical nightmare since their engines guzzled gas like no tomorrow. There was also the combined problem of being so slow and so large that they were easy targets for artillery spotters and bombers and it was near impossible to hide in the field due to it's large profile, so it was easy to disable the tank even before it got into effective range (No matter how much armor you put on a tank, artillery designed to level structures will eventually turn it into an expensive hunk of scrap metal). Overall, commanders found out that it was much better to send out multiple medium/heavy tanks to do the job, than sending a single super heavy. Still, because the idea of a multi-turret warship on treads is universally hella cool, that didn't stop writers from including such weapons in the arsenal of their armies, just to show how powerful they are. Super-Heavy prototypes had cannons that could range between 120mm-280mm, with the Nazis having many of the more absolutely ludicrous designs *cough*Ratte*cough*Maus*cough*. At the end of the day, this whole concept ended up being a useless waste of money in real life, at least until technology improves sufficiently.

Examples: Baneblade, Maus

Tanks in Warhammer 40,000

Since Games Workshop seems to think that tank development in the Warhammer 40,000 universe stopped somewhere between the World Wars, most of the iconic fighting vehicles of the Imperium are a mish-mash of modern and historical designs. We can quibble that some of those vehicles are not really tanks but armored personnel carriers or other specialized classes of armored fighting vehicles, but GW's design team has a serious problem with looping their tracks all the way up and over the chassis for that 1918 flavor, and not even in the correct direction for what they were designed for. A variety of other vehicles in the 40k universe are referred to as tanks, but these are often hovering vehicles like those used by the Tau or Eldar, and thus technically don't count.

Real vs Fictional Tank Designs

Its important to know that games like WH40K subscribes to the rule of cool, rather than logic. So while things like the Land Raider or Baneblade looks cool; in a real combat situation, these tanks would range from highly impractical to down-right detrimental for everyone involved. Here's a short list of why real-world tanks, aren't designed like most fantasy tanks.

Profile

One of the main concerns of a tank designer has always been reducing a tank's profile as low as possible. This is for this main reason: it makes the tank harder to spot, and shoot at, at range. The others are mainly for mobility, like making the center of gravity lower so it doesn't flip over on uneven terrain, or smaller so its able to operate in various locales. Plus smaller tanks mean less material used, so that can be used on another tank or given to another project.

Sure it seems odd that this would be taken into account, given a tank is as large as a city bus; but since WW2: it wasn't really that hard to disable a tank (rocket launchers, mines, anti-tank guns, AT grenades, aerial bombers, artillery, better concealed tanks, to name the most common), if your opponent had the weapon to do so, and if they didn't: making a tank unnecessarily large just made it easier for your opponent to spot you. Thus, making your tank's profile as low and small as possible, contributed in making it less of an easy target, while still being able to act like a priority target for your opponent.

As with so many other aspects of tank design, there is a trade-off involved. Making a tank too small can compromise its ability to function as intended on the battlefield. Interwar tankettes were the most extreme example of this, with some that were smaller than the average automobile but lacking armament more powerful than a machine gun and armour that could protect against the same. With larger tanks, you could still run into similar problems by simply not leaving enough space for sufficiently powerful armament or engines (a problem which plagued many British tanks during the Second World War) or by making it too cramped for the crew to efficiently work with (which is common to many Soviet tanks before and after the Second World War).

Speed

Like what we've described above: it wasn't that hard to stop a tank with the proper armaments (or at least avoid it once spotted) and once your opponent has the guns to stop it, your hulking behemoth will slowly turn into a liability soon enough. (And even if they didn't have the guns; that makes your tank too-slow of a threat, which beggars the question as to why have it there in the first place).

Tanks were also pretty vulnerable on their own, requiring infantry support to deal with targets at close range (the co-axial gun only had limited elevation and was slow to aim as the entire turret had to face the target, and the pintle-mounted gun was limited to the line of sight of the gunner) as a nutter with a powerful-enough explosive could easily run/sneak to an unsupported tank and blow it to smithereens, or disable it (which pretty much meant the tank is still toast).

Nazi Germany got around this problem by using mechanized infantry (troops transported in vehicles) to support their armored forces, so everyone picked up on that and started making tanks fast enough to keep up with infantry transports to create a combined-arms assault, allowing tanks to deal with hard targets while infantry dealt with other targets that were too small for the tanks to take care of.

So, people started distancing themselves from heavyweight tanks, and started using lighter, but more faster tanks in modern combat (plus advances in modern technology made it that even a medium tank could still be as survivable and powerful as a true heavy, while still retaining maneuvrability).

Mobility

An immobile tank, is a dead tank, so people have gone to great lengths to either reduce, or outright remove the many ways on how infantry could disable a tank from moving; but the most common of this is by taking out the tracks with mines or explosives. This was partly fixed by putting the tracks at ground level, covering the tracks with armor, and adding additional armor skirts to further guard it from attacks from the side, ensuring that little of the tracks were exposed to direct enemy fire. Sure it was still vulnerable up-close and mines can still do a number on it, but that's what your infantry support is for (you did bring them, right?).

While the British Mark 1's rhomboid-tracks looks cool; having that on a tank today made it incredibly easy for an opposing force to disable your vehicle, as the tracks could be easily targeted. Plus even if you were to cover it in armor; it made your tank unnecessarily bigger, and people wanted to make their tanks as low and small as humanly possible. It also made maintenance and repairs unnecessarily complicated (Have to repair the tracks? Too bad, now you gotta get on top of your tall tank to fix that. Hope snipers aren't watching.).

Also while the sponson-mounted guns look cool, they're useless in modern tank combat. Apart from the obvious issues of being unable to bring your full-firepower to bear if your opponent isn't situated right infront of you AND that they have to be larger than the width of your tank: having two of your sophisticated weapon systems near ground level meant a plethora of reliability issues (went through water or muddy terrain? Pray to the Machine God your gun doesn't malfunction if you didn't clean that right away. Went through a building? Hope all that rubble didn't tear off anything important.).

Also note that this setup was done to for trench and fortification clearing, not tank vs tank combat (since WW1 focused on trench warfare than mechanized assaults). Having your turret in be centered with the hull itself, either with a turret or having it built into the tank itself to save on parts, was infinitely more effective. It also made weight distribution more balanced, which made it easier for tanks to maneuver in rough terrain.

Logistics

This should be an obvious point, but the Imperium of Man has only been able to create and maintain ludicrous super-heavy tank designs, because they have the aid of the Mechanicus (even if they've been reduced to a shadow of their former glory) to assist with creation and maintenance, plus having access to thousands of planets full of resources to get materiel and fuel from. Plus the creative liberties of simply accepting that: "It just works" and "THE FUTURE", because it'd be boring if we had to explain that a Forgeworld couldn't build a Baneblade because some mining world couldn't produce the output or the resources for it were earmarked to other projects, rather than something more exciting, like foul traitors constantly assailing their supply lines, or the techpriests needs some McGuffin stolen by the Orks.

Another design point for tanks is resource economy. It had (and still has) to be produced using, and maintained with, the least possible amount of resources whilst still being formidable in it's role. If an army would deploy superheavies today, just remotely near the scale of how Imperial forces do during wartime; they'd be bankrupt and end up with a lopsided army. If creation didn't eat up most of their supplies; the amount of resources they'd need to keep these war machines maintained would put the US Army to shame. Once they realize they can't keep it up; they'd start scrapping those and scramble to turn them into practical tanks (assuming they still had fuel left).

Armaments

Putting two cannons as your tank's main armament like C&C's Mammoth Tank looks neat like the, or UNLEASHING ELEVEN BARRELS OF HELL sounds awesome, but that had it's own set of problems. One is that putting a lot of main guns on your tank requires you to make the chassis bigger, as you need more room to accommodate the guns, ammunition, and larger engine (as you need more power to keep that sucker mobile), which makes it an even bigger target.

Another is that its a waste of resources; those other main guns, ammo, and materials, would be better put in making another tank, and two tanks are still more threatening than one. It is also either overkill, as the main guns of today's battle tanks can typically penetrate tank armor easily enough, or worthless since if you did meet a tank with armor too strong for your guns, having more of them is not gonna help. The probable rate-of-fire, firepower, or accuracy advantage you have over tanks with only one gun, would be easily off-set with autoloaders, specialized ammunition, better targeting systems, and/or a well-drilled gunner crew. That or an auxiliary missile launcher, which is loads more practical and cost-effective.

One more, is that in the event your tank is destroyed; that's a massive ammo-cookoff you're looking at, which can be dangerous to both the crew and surrounding friendlies.

Character Role

See also Combat roles for other roles

In many role-playing games, particularly the online ones, the term "tank" has also arisen to describe a character whose primary purpose is redirect all damage from enemies to himself. This was one of the primary purpose of actual tanks as well; tanks, being as armored and threatening, are supposed to get most of the enemy's attention while the squishier units like infantry and light vehicles move into advantageous positions to deal more damage, without the threat of serious retaliation.

See, many enemies in RPGs have way too much health, deal way too much damage for most classes to withstand, and fights with them are unlikely to be decided in one round unless they're uncharacteristically vulnerable to save-or-die rays (which almost never happens).

Furthermore, many of the classes that are best at dealing damage (assassin and wizard types, for example) often have very little survivability when it comes to being punched in the face, in order to balance out classes. If a class can both tank damage and deal high damage at the same time, they either render other classes redundant or can do neither as well as a dedicated tank or damage dealer. (This is where the gaming term differs from the historical/military term - a "pure" tank (unit role) is strictly something that attracts and survives damage, without much or even necessarily any of the punch a tank (vehicle type) has.)

Thus, demand is created for a character whose job is to redirect enemies' aggression away from the squishy members of the party and towards them instead, usually using their mastery of mind-control, irritating sound effects, imposition of dangerous effects for attacking anyone else, or simply cutting insults and rude gestures which draw attention to themselves. They also tend to have abilities that help them in resisting, mitigating, avoiding, or regenerating from some of the damage they suffer (and on occasion act as a secondary damage dealer). In most cases, tanks are also often reliant on healer classes as well to keep them alive while they do their thing, as enemies that require tanks can usually deplete a good chunk of their health in a few attacks. Making sure that chunk is constantly restored is required to make sure they can keep at it.

Fourth Edition refers to this role as the "defender," while Dawn of War 2 vets will recognize it as the "Tarkus", and later the "Diomedes." While it is most obvious in online video games, the necessity of drawing fire away from squishier party members toward tougher ones who can take a beating exists in a variety of different games, from cooperative card games to MOBAs. The wargame equivalent would be the DISTRACTION CARNIFEX.

See Also

• Team Yankee - a tabletop game that revolves around late Cold War tank warfare, with plenty of info on real-world tanks.

Vehicle Warfare
Combat Aircraft - Siege Weapons - Tank - Warship