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Tank classification is a taxonomy of identifying either the intended role, or weight class of tanks. The classification by role was used primarily during the developmental stage of the national armoured forces, and referred to the doctrinal and force structure utility of the tanks based on design emphasis. The weight classification is used in the same way truck classification is used, and is intended to accommodate logistic requirements of the tanks. Modern tank designs have favoured a "universal" design that has generally eliminated these sorts of classifications from modern terminology, which tends to refer to almost all designs as main battle tanks despite sometimes significant weight differences.

The most common division in the role has been between tanks intended to focus on fighting either with or against infantry, and tanks intended for fighting against other AFVs, especially other tanks. The British referred to these as infantry tanks and cruiser tanks respectively, although the latter was expected to exploit holes in the enemy lines and "cruise" at high speeds behind the lines. Other specialist roles include anti-tank vehicles or tank destroyers which are generally highly armoured compared to similar generation multi-purpose tanks, and assault guns that mount oversized and typically low-velocity guns, for attacking fortifications.

Weight-based classifications are useful, but only in reference to a period's other tanks. For example, a medium tank at the end of World War II would have been considered a heavy tank at the beginning. Light, medium, and heavy have other meanings than just weight, e.g., relating to gun size, the amount of armour, or speed. In many cases the weight of armour was a side effect of their intended role, light tanks were generally used for reconnaissance, mediums were similar to British cruisers, and heavy tanks were used for roles similar to the British infantry designs.

As an example, in the mid-1930s to early '40s, Nazi Germany developed a new generation of combat tanks after its Panzer I. It resulted in: the 'medium' Panzer III, armed with an anti-tank gun and intended to, like the British Cruiser tanks, speed past enemy positions to attack the rear; and the 'heavy', 'infantry support' Panzer IV, initially armed with a 75mm short-barreled gun for engaging bunkers and other static defences, with strong frontal armour but weak side and rear armour, the thought being the infantry supporting it would keep it from being flanked. The differentiation was not absolute: the IV could fire HEAT shells and the III could fire high-explosive shells to attack infantry, but neither was as effective in the roles of the other. By the start of World War II, the Pz IV would be a medium, and the III, light-medium, when compared to French tanks of the time.

As the war progressed, tanks, heavier anti-tank guns, and tank-versus-tank combat became much more common on the battlefield. In order to survive, all tanks required an increase in armour protection and larger guns in order to defeat a similar "up-armouring" taking place on the enemy's own designs. The separation of "infantry" and "cruiser" roles generally disappeared and the "universal tank" started to take over. These were generally classified by weight in comparison to tanks from their own country; for instance, the US fielded the M26 Pershing "heavy" tank, which was heavier than the M4 Sherman. However, the Pershing was very comparable to the German Panther tank which Germany considered a medium, due to the presence of its much larger Tiger II.

Classifying tanks

Many classification systems have been used for tanks over the nearly one hundred years of their history. Classification has always been determined by the prevailing theories of armoured warfare, which have been altered in turn by rapid advances in technology. No one classification system works across all periods or all nations.

Tanks are often referred to by weight-based classification, such as 'light', 'medium' or 'heavy', which may also imply tactical roles. Many types are also described by their tactical role, which depends on contemporary military doctrine. For instance, 'infantry' and 'cruiser' tanks are British classifications of the 1930s and '40s; 'infantry', 'fast', and 'breakthrough' are contemporaneous Soviet types. Furthermore, expected weights for a given tank type vary over time; a medium tank of 1939 could weigh less than a light tank of 1945. Some examples:

• The British Mk II Matilda Infantry tank weighed as much as a German Panzer III or Panzer IV medium tank. Due to its heavy armour it had some of the traits of a heavy tank, but the gun was typical of a light or medium tank of the period.
• German Panzer IV tanks were often referred to as 'heavy' tanks in 1939 and 1940, because they had high-calibre armament designed to attack infantry positions. However, the Panzer IV is usually regarded, and was primarily employed, as a medium tank.
• American M26 Pershing tanks were designated as 'heavy', despite being closer in performance to a Panzer V Panther medium tank than a Panzer VI Tiger heavy tank.
• Soviet T-34/85 medium tanks used 85mm guns, comparable in calibre to 88mm guns on Tiger heavy tanks. However, because of their armour and speed, and their weapons' strength, the two are ranked in different classes.
• Soviet IS-2 tanks were classified as heavy due to the impenetrability of their well-designed armour and large 122mm gun, although they weighed only about half as much as a Tiger and about the same as the German Panther, classified as a medium. Used well, it was more powerful than either of those tanks.

Overview

British and Soviet tacticians up to the time of the Second World War classified tanks into three major roles: infantry, light, and cavalry. Infantry tanks were to be distributed to infantry units, to integrally support dismounted infantry actions. Light tanks performed the traditional cavalry role of scouting and screening. Cavalry or "cruiser" tank units were meant to exploit breakthroughs and fight other armoured formations. Even into the 1930s, some soldiers saw tanks as merely serving in support roles for large conscript armies of foot soldiers and horse cavalry.

But even before the end of the First World War, some military theorists such as J.F.C. Fuller, and later Basil Liddell Hart, formulated a different image of combined-arms armoured warfare, featuring independent, professionally manned tank units. The conditions of the Treaty of Versailles forced Germany to build an armed forces essentially from scratch, allowing it to more easily abandon conservative theories and develop Blitzkrieg tactics.

The infantry and cavalry tank roles were abandoned by the end of the Second World War. WWII tanks were generally classified by weight and role: fast, relatively inexpensive light tanks for reconnaissance, general-purpose medium tanks, and slow heavy tanks for breakthroughs and long-range fire. Combat experience helped weed out unsuccessful designs.

After WWII, less expensive armoured cars and more specialised tracked vehicles gradually took over the reconnaissance role. Heavy tanks were shown to be incapable of keeping up with mobile warfare, but advances in engine, weapon, and armour technology allowed medium tanks to acquire the best characteristics of heavy tanks—the ultimate in mobility, firepower, and protection were rolled into the extremely optimised main battle tank (MBT).

Some of the names developed for tracked AFV and tank types over history:

• Up to 1918:
  • 'male', 'female' (referring to armament; male tanks were armed with machine guns and one or more cannon while female were armed with machine guns only); light tank, medium tank, heavy tank
• 1918 to 1950:
  • tankette, armoured reconnaissance, fast tank, cruiser tank, cavalry tank, assault tank, infantry tank, light tank, medium tank, heavy tank, super-heavy tank
• 1950 to present:
  • main battle tank, infantry fighting vehicle, Boyevaya Mashina Pekhoty (BMP, infantry fighting vehicle), Stridsfordon ("Combat Vehicle"), Cavalry Fighting Vehicle

Tank generations

Tanks are sometimes classified as belonging to a particular generation, although the actual definition and membership in these generations is not clearly defined. Soviet and Russian military planners organise tanks into a generation of tanks up to 1945, and four generations of main battle tanks, while Canadian strategists organise main battle tanks into three generations. The military of the People's Republic of China also recognises three generations of its own tanks.

Tank types

There were many names given to different tank types, and similar names did not assure similar design goals. Some light tanks were relatively slow, and some were fast. Some heavy tanks had large-calibre, low-velocity, anti-infantry bunker-busters, and some had high-velocity anti-tank guns.

WWI tank types

File:Medium Mk B.jpg

Medium Mark B, a late-1918 British tank.

In WWI, the first tank, the Mark I, was designed for supporting infantry by crossing trenches and attacking machine-gun posts. Initially, there were two types with two roles: the 'males', armed with artillery guns, and the supporting 'females', armed with anti-infantry machine guns to protect the 'males'. The tanks that followed were described relative to it, including light, medium, and super-heavy tanks—for example, the light tank FT-17 (approximately 7 t / 15,000 lb.) and the medium Medium Mark A 'Whippet' (14 t / 31,360 lb.). By the end of the war, the Mark I (~30 t / 56-60,000 lb.) could be classified as a medium tank, and the Whippet as a light tank. Super-heavy breakthrough tanks such as the Char 2C (69 t / 158,000 lb.) or the K-Wagen (120 t / 275,000 lb.) were nearly completed before the war ended. In comparison, the current British MBT, the Challenger 2, weighs some 60 t (137,500 lb).

Tank development: 1930–1945

File:Bt2.jpg

The BT-2 tank of 1932 was the first Soviet improvement of J. Walter Christie's design.

Tank models were developed before and during WWII according to different philosophies, with different combinations of armour, mobility, and armament. Each major nation developed its own doctrine of tank use, and therefore different tank models to suit. New doctrines explored the role of the tank as a fast-striking unit, while technological improvements led to the invention of engines, tracks, transmission, and suspension, which made tanks more reliable over a long distance. The ideas of the American inventor Walter Christie were important in establishing the fast tank concept.

Tank doctrine in the UK declared that one group of tanks would accompany infantry in a similar role to WWI, while another group of 'cruiser' tanks would then exploit a breakthrough, in a role similar to cavalry.

In the USSR, 1930s' tank doctrine specified three groups of tanks: one 'breakthrough' tank in the infantry support role, one tactical breakthrough tank to clear the combat area, and a 'fast tank' for operational maneuver.

In Germany, the ideas of Guderian established the need for unified tank formations, but with a mixture of armaments for differing roles.

In the USA, doctrine evolved so that the main purpose of the tank was to provide support to mobile infantry, while divisions would be provided with battalions of tank destroyers to combat enemy tanks themselves. There was no analog to the cruiser tank in pre-war US doctrine, and tanks were expected to be used only along with infantry. There were those within the US Army which advocated a more modern force with tanks in the cavalry role, but their suggestions were not put into place by the time of the US's entry into WWII.

These doctrinal differences are important when considering WWII tank classifications.

Infantry tank

Main article: infantry tank

A British Matilda tank displaying a captured Italian flag

The idea for this tank was developed during World War I by the British and French. The infantry tank was designed to work in concert with infantry, moving mostly at a running pace, which let it carry much heavier armour than the average tank. Its main purpose would have been to clear the battlefield of obstacles, kill enemy soldiers, and protect the infantry on their advance into and through enemy lines by giving mobile overwatch and cover.

One of the best-known infantry tanks was the Matilda II of World War II. Its armour was thick enough to stop all but the most powerful anti-tank rounds of the period. Its QF 2-pounder gun was sufficient to take on most light and medium tanks of the early war. It should not be confused with the Matilda Mk I, also an infantry tank, which however was armed with only a machine gun. The Churchill and Valentine infantry tanks were also successful models, each with a number of variants, such as some mounting heavier guns like the QF 6-pounder.

Cruiser tank

Main article: cruiser tank

File:Cromwell tank color.JPG

Cromwell tank.

A cruiser tank, or cavalry tank, is designed to move fast and exploit penetrations of the enemy front. The idea originated in "Plan 1919," a British plan to break the trench deadlock of World War I in part via the usage of high-speed tanks (at least, compared to other designs). This concept was later implemented in the "Fast Tanks" pioneered by Walter Christie.

They were used by the United Kingdom during World War II, and early models were thinly armoured and armed with anti-tank guns that could not effectively combat infantry or towed anti-tank weaponry. Cruiser tanks were designed to complement infantry tanks, exploiting gains made by the latter to break through enemy lines and assault from the rear. In practice, they largely proved to be less effective than the German tanks they opposed.

Early cruiser tank designs, such as the A9 and A10, were comparatively lightly armoured, but mobile and reasonably well-armed for the early campaigns of WWII. These earlier designs were largely replaced by larger cruisers such as the Crusader series, though in some cases reverted to even lighter (but better-armoured) scouting tanks, such as the US M3 Stuart. In 1942–1944, British cruiser tank units were reequipped with American M4 Sherman tanks. In 1944, in replacing their tanks, a few units were partially converted back to British equipment: the Cromwell cruiser tanks, which were similarly armed and armoured to the Sherman but significantly faster. The final cruiser tank was the Comet, introduced in late 1944, which was an extremely effective medium tank on a par with the German Panther. The last of the British Cruiser tanks, the Centurion, would be one of the first MBTs.

The Soviet fast tank (bistrokhodniy tank, or BT tank) classification also came out of the infantry/cavalry concept of armoured warfare. Fast tanks differed from Soviet light tanks by an emphasis on speed, and descended from a Christie tank prototype of 1931. The T-34 were a development of this line of tanks as well, though their armament, armour, and all-round capability places them firmly in the medium tank category.

Light tank

A Stuart M5A1 light tank at the Worthington Tank Museum.

Light tanks tend to be smaller, faster, and lighter vehicles, and cheaper to produce. The weight of a 'light' tank increased markedly during WWII. For example, the M24 Chaffee was a purpose-built light tank of late WWII, but weighed more than the Panzer III, a mainstay medium tank from 1939-43 but obsolete at the time the Chaffee was introduced. Some light tanks are able to move over land rapidly compared to heavier tanks and are maneuverable through obstacles such as jungle thickets, while maintaining lethality against enemy infantry. The Imperial Japanese Army exploited this ability of their light tanks during the Battle of Malaya. However, many other light tanks are no more mobile than their heavier cousins, in part because the emphasis on economy meant they often were powered by standard light truck engines rather than the larger, heavier, but much more powerful medium tank engines.

Light tanks were quite common at the start of World War II, being the main element of German, Polish and French formations in the Polish and French campaigns, but during the war were relegated to reconnaissance roles because of the increasing firepower of tanks and anti-tank weapons. Some were amphibious, and some, like the Tetrarch, were small enough to be airlifted to battle. They were often preferred over armoured cars for scouting. The Soviet Union even built an experimental winged tank which ultimately was never put to practical use.

The USSR experimented with giving infantry units detachments of light tanks (e.g., the T-70) to provide armoured support. The idea was a failure because the tanks' armour was readily penetrated by German anti-tank weapons, and their firepower was inadequate for fighting other tanks or destroying field fortifications.

After WWII, light tanks continued in the reconnaissance role for some time, thanks to their modest cost and potential for amphibious capabilities, but were eventually replaced by infantry carriers and armoured cars.

The French WWII-era Light Tank (Char Léger) type was generally similar to other nations' light tanks of the period. Since it was intended to be used for infantry support rather than scouting, it was slower than most light tanks, giving it the weaknesses of the type, but no compensating advantages. The French intended the Armoured Reconnaissance (Automitrailleuses de Reconnaissance) and Armoured Combat (Automitrailleuses de Combat) for scouting and light combat roles.

Medium tank

Sherman medium tank from World War II, the workhorse of U.S. armoured forces

Medium tanks are simply neither the heaviest nor lightest in weight, and many of the designs had successful balance of firepower, mobility, protection, and endurance, and could often be adapted to a variety of roles. In WWI, the very first Mark I tank turned out to be a medium tank when compared to the range of designs of the time.

Medium tanks of the intra-war period included the British Vickers Medium Mark II, the French Char B1, and the Soviet multi-turreted T-28. During this period they were often considered by the traditional tactical roles as infantry tanks and cavalry tanks, rather than by weight class.

There were medium tanks that focused on anti-infantry capabilities (such as in WWII: the Panzer IV short-barrel, and the 75mm-turret M4 Sherman), and medium tanks which were more focused on the anti-tank role, mounting high-velocity tank guns. The French Medium Tanks (Chars Moyens) were much the same as their light tanks, but of a heavier sort and intended for infantry support. Their Cavalry Tanks (Chars de Cavalerie) focused on speed in addition to power and protection of the other designs. They were similar to what other countries called medium tanks.

When Soviet tank designers were preparing a successor to the BT Fast Tank series, they combined its excellent mobility with thick, sloped armour and the unprecedented firepower of a 76-mm high-velocity gun. The result was the T-34 medium tank, whose superbly balanced capabilities shocked the German Wehrmacht when it invaded the Soviet Union. The lessons of Blitzkrieg, first employed by the Germans and eventually adopted by other nations, found their best expression in formations of mutually-supporting medium tanks and motorised infantry. The traditional view of infantry and cavalry tank roles was rendered obsolete.

As well, the Soviet Union and the United States both benefited from their ability to manufacture a well-balanced medium tank in incredible numbers—about 57,000 T-34s and 49,000 Sherman tanks were built during the war.

During and after the war, the roles of light tanks were gradually taken over by less-expensive armoured cars and specialised reconnaissance vehicles. Heavy tanks, having shown their limitations in WWII, experienced a limited arms race of progressively more heavily-armed and armoured designs, but these too were eventually phased out in favour of increasingly capable and flexible medium tanks. Simpler and more economical self-propelled guns, and later anti-tank guided missiles, came to fulfill fire-support and anti-tank roles, allowing tanks to become more specialised for mobile warfare.

With the production of relatively expensive tanks converging more and more on the sweet spot of the versatile medium tank, the way was paved for the development of mechanised warfare and the modern main battle tank concept.

Heavy tank

The German Tiger tank

Heavy tanks have usually been deployed to fulfill the need for a breakthrough tank, though in practice have been more useful in the defensive role than in the attack. Design goals have included attacking obstacles, creating breakthroughs, and engaging enemy armoured formations. They feature very heavy armour and weapons relative to lighter tanks, though they tend to push power plants to the limits. As a result they tend to be either underpowered and comparatively slow, or have engine and drive train problems from overworking their engines.

The first tank, the Mark I of World War I, was designed around this philosophy. So was the Char 2C, one of the largest tanks ever produced. At the start of World War II, the French and the Soviets were the only countries to have inventories of heavy tanks, such as the Char B1, T-35, and KV-1. The Matilda II infantry tank, though not as heavy as the others, had thicker armour than most tanks in service at the time. Later war examples were the German Tiger I and II, as well as the Soviet IS series. Note that "heavy" versus "medium" is more a question of tactical roles than weight; the Pz.Kpfw. V Panther, for example, was a "medium" tank that outweighed most Allied "heavy" tanks.

Heavy tanks achieved their greatest successes both fighting other, lighter tanks, and destroying fortifications with their very large guns. Although it is often assumed that heavy tanks suffered inferior mobility to mediums, this was not always the case, as many of the more sophisticated heavy tank designs featured advanced suspension and transmission precisely to counteract this drawback. The German Tiger, for example, had similar speed and better terrain-handling characteristics when compared to the significantly lighter Pz IV medium tank, albeit at the cost of low reliability.

File:PanzerVI TigerII Porsche1.jpg

A German Tiger II Tank

After World War II came the last major fielding of heavy tanks in addition to mediums, which included the M103 heavy tank, the FV214 Conqueror, and ARL 44, in response to the Soviet T-10. The largest tank guns were approaching maximum calibre whose shell could still be handled by the crew, even using awkward two-part shells and propellants, which greatly slowed their rate of fire. And thanks to improved engine and armour technology, more mobile medium tanks were catching up to them in the amount of firepower and protection they could carry. After this, the role of medium and heavy tanks merged, and came to be known as the Main Battle Tank (MBTs), with no specialised super-heavy tanks being fielded. Less expensive assault guns and artillery pieces could fulfill the heavies' anti-infantry role.

Heavy tanks were finally rendered obsolete by anti-tank guided missiles and high explosive anti-tank (HEAT) ammunition. The much more flexible missiles are effective at ranges beyond a tank gun's range, and sheer armour mass was no longer a guarantee of survivability against the largest HEAT warheads of tank guns or missiles.

Super-heavy tank

Main article: Super-heavy tank

There were a few rare tanks informally called "super-heavy tanks." As their name implies, most of these tanks were extremely heavy such as the impractical German Panzer VIII Maus, which buckled roads. Super-heavy tanks featured thick armour, which was generally impervious to most weapons of their time. The armaments of these immense tanks were usually heavy artillery guns. Most of these super-heavy tanks only reached pre-prototype stage, while some never even left the drawing board, such as the Landkreuzer P. 1000 Ratte and Landkreuzer P. 1500 Monster. WWII and the following post-war period saw the quick zenith of super-heavy tanks with the conception of the German P-series tanks, British experimental Tortoise tank and American T-28 Gun Carriage. The super-heavy tanks had an extremely short career; air units were too much of a threat for lumbering behemoths which were all too liable to get stuck in various terrain. And with the development of rockets and missiles, the super-heavy tank quickly saw its decline. In short, super-heavy tanks were merely an extension of World War I ideals regarding heavy assault guns placed on self-propelled carriages, emulating the railway guns and heavy artillery of their time, and with the rise of missiles and rockets, extremely long-range guns became obsolete.

Some designs called "heavy assault tanks" were actually heavy self-propelled guns, including the German Jagdtiger, as well as the experimental wartime British Tortoise heavy assault tank and U.S. T-28 Super Heavy Tank.

Main battle tank (late twentieth century)

Main article: Tank

British Army Challenger II is an advanced heavily armoured modern main battle tank that utilises Chobham armour.

US Marine Corps M1 Abrams tank.

File:Korean Army K1A1 tank.jpg

K1A1 of the Republic of Korea Army

Modern Leopard 2 A6M of the German Army

Advances in tank design, armour, and engine technology allowed tank designers to increase the capabilities of tanks significantly without always resorting to heavier designs, although weights did gradually increase. HEAT ammunition was a huge threat to tanks and could penetrate steel armour thicker than was practical to put on a tank. Advances such as the British-designed Chobham armour limits the effectiveness of weaker HEAT rounds, but the vulnerability still remained. The demise of the heavy tank meant that what had been medium-sized vehicles were now the heaviest. What remained were developments of the heavier cruiser tanks of Britain, and medium tanks intended for anti-tank work of other nations, but with more focus on weapon power and mobility than before. The name "main battle tank" (MBT) gained widespread use.

Many Cold War MBTs evolved more or less directly from late WWII medium tank designs. The US Patton series of tanks was a series of successive evolutions of the M26 Pershing, for example, and the Russian T54/55 was a direct descendant of the T-44, itself an evolution of the T-34. This means than many MBTs retained something of their "medium tank" origins in terms of their balance size, weight, mobility, and protection. However, in the 1960s and 1970s, a generation of purpose-designed main battle tanks appeared, starting with the British Chieftain tank. These vehicles are less obviously influenced by wartime templates (the Chieftain, for example), weighing as much as a WWII Tiger tank and possessing far greater firepower and armour, whilst retaining the mobility of the previous Centurion design. Similarly, the US M1 Abrams series, the German Leopard 2, and British Challenger tanks sit in a nebulous area between what was once considered the "medium" and "heavy" weight category. Perhaps the most defining feature of the main battle tank type is neither its weight, mobility, nor firepower, but instead the idea that only one type of heavily armoured vehicle is required to carry out the roles of breakthrough, exploitation and infantry support.

The term "main battle tank" is applied to tanks designed to function as the backbone of modern ground forces. It is armed and armoured to face as many kinds of threats as possible, but especially direct hits from other tanks and lighter infantry anti-tank weapons. However, the threats to MBTs on a modern battlefield are numerous.

Even heavily armoured MBTs are vulnerable to anti-tank weapons, which are often designed to attack their most vulnerable locations; the top, the bottom, and the tracks. Tanks also retain much of their vulnerability to artillery fire and mines. While a tank can afford to have half a metre of armour on the front, it can't have such a thick slab of metal guarding all of its sides without losing major maneuverability.

The response was to focus on the traits that allowed the tank to survive; protection, mobility and firepower. The amount of armour added was usually sufficient to stop at least previous-generation projectiles from penetrating. Armour on more advanced Western MBTs has been shown to deflect current generation projectiles at at least their frontal armour, but there is little public information on the armour levels of the latest MBTs, as such information is generally kept secret.

Some of the known examples are from friendly fire: In the 1991 Gulf War it was shown that a U.S. Hellfire anti-tank missile disabled but didn't destroy an M1 Abrams, with the crews surviving. M1 Abrams were found to be able to survive 120mm and 125mm sabot rounds at front and side armour. A 120mm round did penetrate the rear of the tank, which set off the ammunition and activated the blow out panels. Later it was concluded that the vehicle could have continued the war after fixing the hole in the back and recalibrating the gun.

During the 2003 invasion of Iraq, a Challenger 2 was fired on by another, hitting the rear bustle ammunition where the resulting fire cooked off the ammunition. This attack injured crew members asleep on top of the tank. Another Challenger hit only received minor cosmetic damage.

Most combat experience regarding modern western tanks states they are very capable of surviving multiple hits at their front and sides.

The German army conducted several tests:

• A Leopard 2 A5 shot by another Leopard 2 A5 required 7 hits to penetrate the front armour.
• A Leopard 2 A4 shot by a T-80 proved that the T-80 could only penetrate its armour at less than 1200m.
• A similar test in which a Leopard 2 A5 shot a brand new T-80U and T-72 (aiming at the thickest part of the armour) proved that at a range of around 2km the 120mm rounds went straight through both targets (in through the front out through the back). (In reality there were no tests of T-80 in Germany, only old East-German T-72Ms.)

When looking at these tests, one has to keep in mind that the units might have been monkey models, that is, models for export that have degraded characteristics.

The Leopard 2, AMX-56 Leclerc, M1 Abrams, Challenger 2, and Merkava Mark IV are widely considered to be the most heavily armoured and armed main battle tanks in the world.

21st century

Mobile Gun System, a possible wheeled replacement for tanks.

On several occasions the tank has been declared obsolete, and expected to disappear from the battlefield. The first such declaration came about because of the introduction of wire-guided missiles in the 1960s, which allowed a small team, typically two men, to defeat any tank on the battlefield at fairly long ranges. Tank designers responded with increased armour, composite armour, and reactive armour systems, which while they do not entirely defeat this threat, require the size and weight of a missile needed to defeat a modern MBT to be much larger and less portable.

This declaration was made again in the 1970s with the widespread introduction of larger missiles, this time mounted on helicopter gunships.

In more modern times the ending of the Cold War has once again led to a discussion of the role of the tank on the modern unconventional warfare "battlefield." Rapid deployment and mobility when fighting light forces appears to be much more important than capabilities against other tanks. In the first decade of the 21st century, Canada had begun to liquidate its park of 30-year-old Leopard tanks in favour of the eight-wheeled Mobile Gun System, but has reversed the decision and is acquiring 100 Leopard 2 A6 main battle tanks in 2007 as experience in Afghanistan. Belgium has recently re-equipped its two tank battalions with 8×8 wheeled vehicles.

To accommodate for the changing role the manufacturer Krauss Maffei Wegmann has designed a concept-Leopard 2 called the PSO (peace support operation) that is supposed to be more fitted for tasks in peace-keeping operations and in urban areas (not normally a favorite area of deployment for MBTs).

Specialist tanks

An M60A1 Armored Vehicle Launched Bridge (AVLB), deploying its scissors-type bridge.

Tanks have often been modified for special purposes. The most common is to provide armoured capability for combat engineers. These include tanks carrying large-calibre demolition guns, with flails or ploughs for mine-clearing, or flame tanks armed with flamethrowers. The tank occasionally may lose its weapons and the chassis alone may be used, as in bridge-laying tanks.

Notable among wartime examples which formed Hobart's Funnies was the Churchill AVRE, which was equipped with a weapon for destroying bunkers and other fortifications but also able to mount other equipment.

Another important modification was the amphibious tank, such as the Sherman Duplex Drive (DD). These designs were modified with waterproofing and propulsion systems, to be able to traverse open water. Their most notable usage was on D-Day.

Many specialist tank roles have been assigned to other vehicle types, though many tank chassis are still used for a wide variety of vehicles, ranging from anti-aircraft roles to bridge layers.

Unmodified tanks can be fitted with equipment, such as mine-clearing ploughs, to give them ancillary roles.

See also

• Armoured fighting vehicle classification
• Comparison of early World War II tanks
• History of the tank
• Hull-down
• List of main battle tanks by country
• List of main battle tanks by generation

References

• Lamontagne, J.G. Pierre (2003). Are the Days of the Main Battle Tank Over?. North York, Ontario: Canadian Forces College. (PDF)
• Sewell, Stephen ‘Cookie’ (1998). “Why Three tanks?”, in armour vol 108, no 4, p 21. Fort Knox, KY: US Army armour Center.