tankless, adj.tanklike, adj.
/tangk/, n.
1. a large receptacle, container, or structure for holding a liquid or gas: tanks for storing oil.
2. a natural or artificial pool, pond, or lake.
3. Mil. an armored, self-propelled combat vehicle, armed with cannon and machine guns and moving on a caterpillar tread.
4. Slang. a prison cell or enclosure for more than one occupant, as for prisoners awaiting a hearing.
5. See tank top.
6. go in the tank, Boxing Slang. to go through the motions of a match but deliberately lose because of an illicit prearrangement or fix; throw a fight.
7. to put or store in a tank.
8. tank up,
a. to fill the gas tank of an automobile or other motor vehicle.
b. Slang. to drink a great quantity of alcoholic beverage, esp. to intoxication.
9. Slang. to do poorly or decline rapidly; fail: The movie tanked at the box office.
[1610-20; perh. jointly < Gujarati tankh reservoir, lake, and Pg tanque, contr. of estanque pond, lit., something dammed up, deriv. of estancar ( < VL *stanticare) to dam up, weaken; adopted as a cover name for the military vehicle during the early stages of its manufacture in England (December, 1915)]

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Heavily armed and armoured combat vehicle that moves on two continuous metal chains called tracks.

It is usually equipped with a cannon mounted in a revolving turret as well as lighter automatic weapons. The British developed tanks during World War I to fill the need for an armoured assault vehicle that could cross the muddy, uneven terrain of the trench battle zone. They first saw combat at the Battle of the Somme (1916). In World War II, Germany's tank force was initially the most effective in Europe because it was organized into fast-moving massed formations with great striking power. After World War II, tanks became larger and more heavily armed. Most modern main battle tanks weigh more than 50 tons yet are capable of road speeds of 30–40 mph (50–70 kph). The standard main armament is a 120-mm gun, which fires armour-piercing projectiles; laser range-finders and infrared imaging devices aid in sighting.

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▪ military vehicle
  any heavily armed and armoured (armoured vehicle) combat vehicle that moves on two endless metal chains called tracks. Tanks are the principal type of armoured vehicle. Other major types include tracked and wheeled infantry carriers, which were conceived only for transporting troops into action but which also have been used to some extent for fighting; armoured cars, which often resemble the lighter types of tanks but run on wheels; self-propelled guns, some of which are only partly armoured or wheeled; and such specialized vehicles as armoured recovery vehicles, armoured bulldozers, and amphibious landing vehicles.

      This article first discusses the development of modern tanks from the beginning of the 20th century to the present. It then treats related forms, including amphibious vehicles, self-propelled guns, and armoured personnel carriers.

 Tanks are essentially tracked, protected weapon platforms that make the weapons mounted in them more effective by their cross-country mobility and by the protection they provide for their crews. Weapons mounted in tanks have ranged from single rifle-calibre machine guns to, in recent years, long-barreled guns of 120- or 125-millimetre (4.72- or 4.92-inch) calibre.

Earliest developments
 The use of vehicles for fighting dates to the 2nd millennium BC, when horse-drawn war chariots were used in the Middle East by the Egyptians, Hittites, and others as mobile platforms for combat with bows and arrows. The concept of protected vehicles can be traced back through the wheeled siege towers and battering rams of the Middle Ages to similar devices used by the Assyrians in the 9th century BC. The two ideas began to merge in the battle cars proposed in 1335 by Guido da Vigevano, in 1484 by Leonardo da Vinci, and by others, down to James Cowen, who took out a patent in England in 1855 for an armed, wheeled, armoured vehicle based on the steam tractor.

      But it was only at the beginning of the 20th century that armoured fighting vehicles began to take practical form. By then the basis for them had become available with the appearance of the traction engine and the automobile. Thus, the first self-propelled armoured vehicle was built in 1900 in England when John Fowler & Company armoured one of their steam traction engines for hauling supplies in the South African (Boer) War (1899–1902). The first motor vehicle used as a weapon carrier was a powered quadricycle on which F.R. Simms mounted a machine gun in 1899 in England. The inevitable next step was a vehicle that was both armed and armoured. Such a vehicle was constructed to the order of Vickers, Son and Maxim Ltd. and was exhibited in London in 1902. Two years later a fully armoured car with a turret was built in France by the Société Charron, Girardot et Voigt, and another was built concurrently in Austria by the Austro-Daimler Company.

      To complete the evolution of the basic elements of the modern armoured fighting vehicle, it remained only to adopt tracks as an alternative to wheels. This became inevitable with the appearance of the tracked agricultural tractor, but there was no incentive for this until after the outbreak of World War I. A tracked armoured vehicle was proposed in France as early as 1903 but failed to arouse the interest of military authorities, as did a similar proposal made in England in 1908. Three years later a design for a tracked armoured vehicle was rejected by the Austro-Hungarian and then by the German general staffs, and in 1912 the British War Office turned down yet another design.

 The outbreak of World War I in 1914 radically changed the situation. Its opening stage of mobile warfare accelerated the development of armoured cars, numbers of which were quickly improvised in Belgium, France, and Britain. The ensuing trench warfare, which ended the usefulness of armoured cars, brought forth new proposals for tracked armoured vehicles. Most of these resulted from attempts to make armoured cars capable of moving off roads, over broken ground, and through barbed wire. The first tracked armoured vehicle was improvised in July 1915, in Britain, by mounting an armoured car body on a Killen-Strait tractor. The vehicle was constructed by the Armoured Car Division of the Royal Naval Air Service, whose ideas, backed by the First Lord of the Admiralty, Winston S. Churchill (Churchill, Sir Winston), resulted in the formation of an Admiralty Landships Committee. A series of experiments by this committee led in September 1915 to the construction of the first tank, called “Little Willie.” A second model, called “Big Willie,” quickly followed. Designed to cross wide trenches, it was accepted by the British Army, which ordered 100 tanks of this type (called Mark I) in February 1916.

 Simultaneously but independently, tanks were also developed in France. Like the very first British tank, the first French tank (the Schneider) amounted to an armoured box on a tractor chassis; 400 were ordered in February 1916. But French tanks were not used until April 1917, whereas British tanks were first sent into action on Sept. 15, 1916. Only 49 were available, and their success was limited, but on Nov. 20, 1917, 474 British tanks were concentrated at the Battle of Cambrai (Cambrai, Battle of) and achieved a spectacular breakthrough. These tanks, however, were too slow and had too short an operating range to exploit the breakthrough. In consequence, demand grew for a lighter, faster type of tank, and in 1918 the 14-ton Medium A appeared with a speed of eight miles (13 kilometres) per hour and a range of 80 miles. After 1918, however, the most widely used tank was the French Renault F.T., a light six-ton vehicle designed for close infantry support.

      When World War I ended in 1918, France had produced 3,870 tanks, and Britain 2,636. Most French tanks survived into the postwar period; these were the Renault F.T., much more serviceable than their heavier British counterparts. Moreover, the Renault F.T. fitted well with traditional ideas about the primacy of the infantry, and the French army adopted the doctrine that tanks were a mere auxiliary to infantry. France's lead was followed in most other countries; the United States and Italy both assigned tanks to infantry support and copied the Renault F.T. The U.S. copy was the M1917 light tank, and the Italian the Fiat 3000. The only other country to produce tanks by the end of the war was Germany, which built about 20.

Interwar developments
      The Renault F.T. remained the most numerous tank in the world into the early 1930s. Aware of the need for more powerful vehicles, if only for leading infantry assaults, the French army took the lead in developing well-armed tanks. The original 1918 French Schneider and St. Chamond tanks already had 75-millimetre guns while the heavier British tanks were at best armed with 57-millimetre guns. After the war the French built 10 68-ton 2C tanks with the first turret-mounted 75-millimetre guns and continued to develop 75-millimetre-gun tanks, notably the 30-ton Char B of 1936.

      In the meantime, Britain took the lead, technically and tactically, in developing the mobility of tanks. Even before World War I had ended, work had started on the Medium D with a maximum speed of 20 miles per hour. Between 1923 and 1928 the British army ordered 160 of the new Vickers Medium tanks. They were virtually the only tanks the British army had until the early 1930s and the only tanks to be produced in quantity anywhere in the world during the mid-1920s. The Vickers Mediums stimulated the Royal Tank Corps to develop mobile tactics, and various experiments during the 1920s and early '30s resulted in the general adoption of two categories of tanks. Mobile tanks were intended for the role performed earlier by horse cavalry, while slower but more heavily armoured tanks provided infantry support.

      Before this division into mobile and slow tanks had crystallized, several different designs were tried. The British Independent tank of 1925, with five turrets, started a trend toward multiturreted heavy tanks. Another trend setter was a small turretless tankette, originated in Britain by Major Giffard le Quesne Martel and John Carden in the mid-1920s, and a slightly heavier, turreted two-man light tank. The number of light tanks grew rapidly after 1929, as several countries started to produce armoured vehicles. The Soviet Union was by far the most important producer; on a much smaller scale Poland, Czechoslovakia, and Japan entered the field in 1930–31. Concurrently, tank production started up again in France and Italy. As tank production grew and spread among nations, the value of light tanks armed only with machine guns decreased, and heavier models armed with 37- to 47-millimetre guns for fighting other tanks began to displace them. An early example was the Vickers-Armstrong six-ton model of 1930, copied on a large scale in the Soviet Union (as the T-26). The most successful example was the BT, also built in large numbers in the Soviet Union. The fastest tank of its day, the BT was based on designs evolved in the United States by J.W. Christie, who in 1928 built an experimental model capable of 42.5 miles per hour. Christie's vehicles could run on wheels after the removal of tracks and, far more significant, had road wheels independently suspended. This enabled them to move over broken ground faster than tanks with the earlier types of suspension.

      Although they were relatively well armed and mobile, tanks of the T-26 and BT type were lightly armoured (plates 10 to 15 millimetres thick) and were not, therefore, suitable for close infantry support. This was clearly demonstrated in 1937 during the Civil War in Spain (Spanish Civil War), where T-26 and BT tanks were used by the Republican forces. Even before this time, it had become clear that tanks that moved at the slow pace of the infantry and were therefore exposed to the full effect of antitank guns had to be thickly armoured. This realization led in the mid-1930s to such infantry tanks as the French R-35 with 40-millimetre and the British A.11 with up to 60-millimetre armour.

      Apart from being lightly armoured, the Soviet BT, the equivalent British cruiser tanks, and the German Pz. III also required support from more heavily armed tanks if they were to engage in fighting of any intensity. The need for tanks with more powerful 75-millimetre guns was clearly recognized in Germany, leading in 1934 to the design of the Pz. IV. The problem was realized less clearly in the Soviet Union, even though the T-28 and T-35 multi-turret tanks with 76-millimetre guns were first built there in 1932–33. But the Russians recognized more quickly than others the need for the next step, which was to replace all the light-medium tanks armed with 37- to 47-millimetre guns by medium tanks armed with 75- or 76-millimetre guns. Thus, in 1939, while the Germans were still developing the Pz. III from a 37-millimetre to a 50-millimetre version, the Russians were already concentrating on the T-34 medium tank with a 76-millimetre gun.

      Other armies were farther behind in producing well-armed tanks on the eve of World War II. All but 80 of the 1,148 tanks that Britain had produced between 1930 and 1939 were still armed only with machine guns. Italy was even worse off, with only 70 M/11 tanks with 37-millimetre guns while the rest of its total of 1,500 were small, machine-gun-armed tankettes. The United States had only about 300 machine-gun-armed light tanks. Most of the 2,000 tanks produced in Japan were equally lightly armed. By comparison, France had a more powerful tank force—2,677 modern tanks, of which, however, only 172 were the Char B, armed with 75-millimetre guns. The largest force was the Soviet Union's, which, as a result of a massive production program, started in 1930–31, had about 20,000 tanks by 1939, considerably more than the rest of the world put together.

 The most effective tank force proved to be the German, composed in 1939 of 3,195 vehicles, including 211 Pz. IVs. What made the German tanks so formidable was that instead of being divided between various infantry and cavalry tank units they were all concentrated and used in massed formations in the panzer divisions (panzer division). The successes of the panzer divisions during the first two years of World War II led the major armies to reorganize most of their tanks into similar formations; this resulted in a dramatic increase in production.

 The campaigns of 1939–41, in which armoured forces played such an important role, also intensified the technical development of tanks and other armoured vehicles. The German Pz. IV and Soviet T-34 were rearmed in 1942 with longer-barreled, higher-velocity guns; soon afterward these began to be displaced by more powerfully armed tanks. In 1943 the Germans introduced the Panther medium tank with a long 75-millimetre gun having a muzzle velocity of 3,070 feet (936 metres) per second, compared with 1,260 feet per second for the original Pz. IV and 2,460 feet per second for its 1942 version. The 43-ton Panther weighed almost twice as much as its predecessor and was correspondingly better armoured. Germany also introduced the still more powerful Tiger tank, armed with an 88-millimetre gun. Its final version (Tiger II), at 68 tons, was to be the heaviest tank used during World War II. To oppose it, the Russians brought out the JS, or Stalin, heavy tank, which appeared in 1944 armed with a 122-millimetre gun. Its muzzle velocity was lower than that of the German 88-millimetre guns, however, and it weighed only 46 tons. At about the same time the T-34 was rearmed with an 85-millimetre gun.

      In contrast to the breakthrough role of the earlier heavy tanks, the Tiger and JS tanks functioned chiefly to support basic medium tanks by destroying enemy tanks at long range. German and Soviet armies also developed other heavy vehicles for this purpose, such as the 128-millimetre-gun Jagdtiger and the 122-millimetre-gun ISU, which, in effect, were turretless tanks. In addition, all armies developed lightly armoured self-propelled antitank (antitank weapon) guns. The U.S. Army developed a specialized category of tank destroyers that resembled self-propelled guns in being relatively lightly armoured but that, like tanks, had rotating turrets.

  The turretless-tank type of vehicle originated with the Sturmgeschutz, or assault gun, introduced by the German army for infantry support but subsequently transformed into more versatile vehicles particularly suited for destroying enemy tanks. No such vehicles were produced in Britain or the United States. Throughout the war, however, the British army retained a specialized category of infantry tanks, such as the Churchill, and of cruiser tanks, such as the Crusader and Cromwell (Cromwell tank). The former were well-armoured, and the latter were fast, but none was well-armed compared to German and Soviet tanks. As a result, during 1943 and 1944, British armoured divisions were mostly equipped with U.S.-built M4 Sherman (Sherman tank) medium tanks. The M4 was preceded by the mechanically similar M3 medium, which was also armed with a medium-velocity 75-millimetre gun but mounted it in the hull instead of the turret, because this could be put into production more quickly when tanks were urgently required in 1940 and 1941. Production of the M4 began in 1942, and eventually 49,234 were built, making it the principal tank of U.S. and other allied armoured forces. Successful when first introduced, it was by 1944 no longer adequately armed and should have been replaced by a new medium tank. But the U.S. Army, like the British, adhered to the fallacious doctrine that armoured divisions should confine themselves to exploitation of infantry breakthroughs and did not, therefore, need powerfully armed tanks. Only toward the end of the war did the U.S. Army introduce a few M26 Pershing heavy tanks with a 90-millimetre gun comparable to that of the original German Tiger. Similarly, the British army introduced the prototypes of the Centurion tank with a 76-millimetre gun comparable to that of the German Panther. Otherwise, U.S. and British tanks were well behind the German and Soviet tanks in their gun power.

Postwar tank armament
      After World War II it was generally recognized that all tanks must be well-armed to fight enemy tanks. This finally ended the division of tanks into under-gunned categories of specialized infantry and cavalry tanks, which the British army retained longer than any other. Still not fully recognized, however, were the advantages of concentrating tanks in fully mechanized formations, and the British and U.S. armies continued to divide tanks between the armoured divisions and the less mobile infantry divisions. After World War II, tanks also suffered from one of the periodic waves of pessimism about their future. New antitank weapons, such as rocket launchers and recoilless rifles, and the mistaken belief that the value of tanks lay primarily in their armour protection, caused this attitude. The Soviet (Union of Soviet Socialist Republics) army, however, maintained large armoured forces, and the threat they posed to western Europe as the Cold War became more intense, together with the havoc created by Soviet-built T-34/85 tanks during the North Korean invasion of South Korea in 1950, provided a new impetus to development.

      The development of tactical nuclear weapons (nuclear weapon) in the mid-1950s provided further stimulus to the development of tanks and other armoured vehicles. Nuclear weapons encouraged the use of armoured forces because of the latter's mobility and high combat power in relation to their vulnerable manpower. Moreover, armoured vehicles proved capable of operating in relative proximity to nuclear explosions by virtue of their protection against blast and radioactivity.

      As less emphasis was placed after a time on nuclear weapons and more on conventional forces, tanks retained their importance. This was based on their being recognized, particularly from the early 1970s, as the most effective counter to other armoured forces, which formed the principal threat posed on the ground by potential aggressors.

gun calibre
      In keeping with the importance attached to the ability of tanks to defeat enemy tanks, great emphasis was placed after World War II on their armament. The result was progressive increases in the calibre of tank guns, the development of new types of ammunition with greater armour-piercing capabilities, and the introduction of more sophisticated fire-control systems to improve tank guns' ability to hit targets.

 Increases in gun calibre are well illustrated by the British Centurion, which started in 1945 with a 76-millimetre gun but in 1948 was rearmed with an 83.8-millimetre gun and in 1959 with an even more powerful 105-millimetre gun. Moreover, during the 1950s the capabilities of British tank units were augmented by a small number of Conqueror heavy tanks armed with 120-millimetre guns, and in the early 1970s the Centurions were entirely replaced by Chieftains armed with a new and more effective 120-millimetre gun.

 Similar increases took place in the calibre of Soviet tank guns. After World War II the basic T-34/85 tanks armed with 85-millimetre guns were replaced by T-54 and T-55 tanks armed with 100-millimetre guns. They were followed in the 1960s by the T-62, with a 115-millimetre gun, and in the 1970s and '80s by the T-64, T-72, and T-80, all with 125-millimetre smoothbore guns. The JS-3 and T-10 heavy tanks with their less powerful 122-millimetre guns had by then been withdrawn. This left the Soviet army in the same position as others of having a single type of battle tank as well armed as contemporary technology would allow.

      For a time the U.S. Army also subscribed to a policy of developing heavy as well as medium tanks. But the heavy M103 tank, armed with a 120-millimetre gun, was only built in small numbers in the early 1950s. As a result, virtually the only battle tanks the U.S. Army had were the M46, M47, and M48 medium tanks, all armed with 90-millimetre guns. After the mid-1950s the M47 tanks were passed on to the French, Italian, Belgian, West German, Greek, Spanish, and Turkish armies, and during the 1960s the M48 began to be replaced by the M60, which was armed with a U.S.-made version of the 105-millimetre gun developed for the British Centurion.

 The same 105-millimetre gun was adopted for the Pz. 61 and Pz. 68 tanks produced in Switzerland, the West German Leopard 1, the Swedish S-tank, the Japanese Type 74, and the Mark 1 and 2 versions of the Israeli Merkava. It was also retained in the original version of the U.S. M1 tank developed in the 1970s, but the subsequent M1A1 version of the 1980s was rearmed with a 120-millimetre gun originally developed in West Germany for the Leopard 2 tank. The British Challenger, introduced in the 1980s, was also armed with 120-millimetre guns, but these were still of the rifled type.

      The last years of World War II saw the development of more effective antitank ammunition with armour-piercing, discarding-sabot (APDS) projectiles. These had a smaller-calibre, hard tungsten carbide core inside a light casing. The casing fell away on leaving the gun barrel, while the core flew on at an extremely high velocity. The APDS, which was adopted for the 83.8-millimetre gun of the Centurions, was fired with a velocity of 4,692 feet per second. By comparison, earlier full-calibre, armour-piercing projectiles had a maximum muzzle velocity of about 3,000 feet per second. With this shell the Centurion's 83.8-millimetre gun could penetrate armour twice as thick as could the 88-millimetre gun of the German Tiger II of World War II.

      An alternative type of armour-piercing ammunition developed during the 1950s was the high-explosive antitank (HEAT) shell. This shell used a shaped charge with a conical cavity that concentrated its explosive energy into a very-high-velocity jet capable of piercing thick armour. The HEAT round was favoured by the U.S. Army for its 90-millimetre tank guns and also by the French army for the 105-millimetre gun of its AMX-30 tank, introduced in the mid-1960s. However, during the 1970s both APDS and HEAT began to be superseded by armour-piercing, fin-stabilized, discarding-sabot (APFSDS) ammunition. These projectiles had long-rod penetrator cores of tungsten alloy or depleted uranium; they could be fired with muzzle velocities of 5,400 feet per second or more, making them capable of perforating much thicker armour than all earlier types of ammunition.

      During the 1960s, attempts were made to arm tanks with guided-missile (guided missile) launchers. These were to provide tanks with a combination of the armour-piercing capabilities of large shaped-charge warheads with the high accuracy at long range of guided missiles. The U.S. M60A2 and the U.S.-West German MBT-70 were armed with 152-millimetre gun/launchers firing Shillelagh guided antitank missiles, and the AMX-30 was armed experimentally with the 142-millimetre ACRA gun/launcher. But the high cost, unreliability, and slow rate of fire of the missiles, together with the appearance of APFSDS ammunition and greatly improved fire-control systems, led to abandonment of gun/launchers in the early 1970s.

      The first major postwar advance in fire-control systems was the adoption of optical range finders, first on the M47 tank and then on the Leopard 1, the AMX-30, and other tanks. In the 1960s, optical range finders began to be replaced by laser range finders. In combination with electronic ballistic computers, these greatly increased the hit probability of tank guns. They became standard in all new tanks built from the early 1970s and were retrofitted in many of the earlier tanks.

      Another major development was that of night sights, which enabled tanks to fight in the dark as well as in daylight. Originally of the active infrared type, they were first adopted on a large scale on Soviet tanks. Other tanks were fitted from the 1960s with image-intensifier sights and from the 1970s with thermal imaging sights. These latter were called passive because, unlike active infrared systems, they did not emit energy and were not detectable.

      After World War II an increasing number of tanks were fitted with stabilized gun controls to enable them to fire more accurately on the move (i.e., to keep their gun barrels at a constant angle of elevation even while the tank was riding over bumps or depressions). At first some tanks, such as the T-54, had their guns stabilized only in elevation, but the Centurion already had stabilization in traverse as well as elevation, and this became standard beginning in the 1970s. Afterward, tanks were also provided with independently stabilized gunners', as well as commanders', sights, the better to engage targets on the move.

Postwar tank design and propulsion
      Until the 1960s, tank armour consisted of homogeneous steel plates or castings. The thickness of this armour varied from eight millimetres on early tanks to 250 millimetres at the front of the German Jagdtiger of 1945. After World War II, opinions differed about the value of armour protection. Tanks such as the Leopard 1 and AMX-30 had relatively thin armour for the sake of light weight and greater mobility, which was considered to provide a greater chance of battlefield survival. Other tanks, such as the Chieftain, had heavier armour, up to 120 millimetres thick at the front, and the Arab-Israeli Wars of 1967 and 1973 demonstrated the continued value of heavy armour.

      At the same time, new types of armour were developed that were much more effective than homogeneous steel, particularly against shaped-charge warheads. The new types were multilayered and incorporated ceramics or other nonmetallic materials as well as steel. The first was successfully developed in Britain under the name of Chobham armour. Armour of its kind was first adopted in the early 1970s in the M1 and Leopard 2; it then came into general use in place of simple steel armour.

      Fighting in Lebanon in 1982 saw the first use, on Israeli tanks, of explosive reactive armour, which consisted of a layer of explosive sandwiched between two relatively thin steel plates. Designed to explode outward and thus neutralize the explosive penetration of a shaped-charge warhead, reactive armour augmented any protection already provided by steel or composite armour.

      The increased protection afforded to tanks inevitably increased their weight. Some tanks introduced during the 1950s and '60s, such as the T-54 and AMX-30, weighed only 36 tons, but the Chieftain already weighed 54 tons. Most tanks introduced during the 1980s, such as the M1 and the Leopard 2, also weighed more than 50 tons, and the Challenger weighed as much as 62 tons.

      In spite of the progressive increases in weight, tanks' speed and agility actually increased because they were provided with more powerful engines. After World War II, tank engines had an output of 500 to 800 horsepower, but, starting with the MBT-70, their output increased to 1,500 horsepower. Engines of this power were installed in the M1 and the Leopard 2, giving them power-to-weight ratios of more than 20 horsepower per ton.

      Most tank engines of the immediate postwar years had 12 cylinders in a V-configuration and at first were of the spark-ignition gasoline (gasoline engine) type. But Soviet tanks already had diesel engines (diesel engine), and from the 1960s almost all tanks were diesel-powered. This increased their range of operation because of the greater thermal efficiency of the diesels, and it reduced the risk of catastrophic fires that could erupt if the armour was perforated by enemy weapons.

      The development of gas turbines (gas-turbine engine) led in the 1960s to the use of one, in combination with a diesel engine, in the Swedish S-tank. After that, a 1,500-horsepower gas turbine was adopted to power by itself the M1 and M1A1. A gas turbine also powered the Soviet T-80, introduced in the 1980s. All other new tanks of the 1980s continued to be powered by diesels because of their greater fuel economy.

      Since the speed of tanks over rough ground depended not only on the power of their engines but also on the effectiveness of their suspensions, the latter developed considerably in the postwar era. Almost all tanks adopted independently located road wheels, sprung in most cases by transversely located torsion bars. Exceptions to this were the Centurion and Chieftain and the Merkava, which used coil springs. To improve their ride over rough ground still further, most tanks built during the 1980s were fitted with hydropneumatic instead of metallic spring units.

      The great majority of postwar tanks continued the traditional configuration of driver's station at the front of the hull, engine compartment at the rear, and rotating turret at the centre. The turret mounted the main armament and was occupied by the tank's commander, gunner, and loader. This configuration, introduced by the Vickers-Armstrong A.10 tank designed in 1934, became almost universal after World War II, but after 1960 it was abandoned in some cases in favour of novel configurations. One widely adopted configuration retained the turret but replaced the human loader by an automatic loading mechanism. The first examples of this were on the T-64 and T-72 tanks, whose guns were automatically loaded from a carousel-type magazine below the turret. Another tank with an unconventional configuration was the Merkava, which had its engine compartment at the front and the ammunition at the rear of the hull, where it was least likely to be hit by enemy fire. The Merkava also had a turret with a low frontal area, which reduced the target it presented to enemy weapons.

Amphibious vehicles (amphibious vehicle)
      The need to cross rivers and other water obstacles led to the development of amphibious tanks, beginning with the British Medium D, designed in 1918. Amphibious tanks built during 1920s and '30s sacrificed armament and armour to achieve low weight in relation to their bulk and, therefore, sufficient buoyancy to float. This confined their usefulness to reconnaissance. A late example of this was the Soviet PT-76, introduced during the 1950s.

 After the middle of World War II many other tanks were made amphibious by collapsible flotation screens, which, when erected, allowed even relatively heavy tanks to float. This method was first used with M4 medium tanks during the D-Day landings in Normandy in 1944. Later, flotation screens were permanently installed on the Swedish S-tank, the U.S. M551 Sheridan, and the Scorpion light reconnaissance tank introduced in 1969 by the British army.

      An alternative method to crossing rivers was submerged fording, first tried in 1940 with the British A.9 cruiser and the German Pz. III and IV. After World War II, provision for submerged fording was built into several tanks, including the T-54, T-62, and T-72, the Leopard, and the AMX-30.

 An entirely different problem was posed by amphibious landings from the open seas; to solve it the U.S. Marine Corps developed the Landing Vehicle Tracked, or LVT. Originally built in 1941 as an unarmoured cargo carrier, the LVT quickly acquired armour. Two types evolved: an armoured amphibious personnel and cargo carrier, and a turreted amphibious gun-vehicle for close fire support during landing operations. Altogether 18,620 LVTs were built during World War II; these played a prominent role in the Pacific campaigns from Guadalcanal onward. After World War II, LVTs were successfully used in Korea, notably for the 1950 Inch'ŏn landing. Two new models were built between 1951 and 1957: an LVTP-5 amphibious carrier, capable of carrying as many as 37 men, and an LVTH-6 armed with a turret-mounted 105-millimetre howitzer. They were followed in the 1970s by the 22.8-ton LVTP-7, which incorporated several improvements, the most important being a boatlike hull with a stern instead of bow loading ramp and two water-jet propulsion units that greatly improved its performance in comparison with that of the earlier LVTs (which were propelled in water as well as on land by means of their tracks). At the same time the LVTP-7 retained the seagoing qualities of the earlier LVTs, which could negotiate rough seas and Pacific surf in contrast to other amphibious vehicles intended primarily for crossing inland water obstacles. The use of water-jet propulsion units in the LVTP-7, however, had been preceded by their use in several amphibious reconnaissance vehicles, including the Soviet PT-76.

Self-propelled guns
 Self-propelled guns are field artillery, antitank guns, or antiaircraft guns mounted on and fired from tracked or wheeled vehicles. The vehicles are armoured to varying degrees.

      The development of self-propelled guns continued after World War II, except for self-propelled antitank guns. These became superfluous when it was recognized that all tanks needed to be sufficiently well-armed to fight enemy tanks. Turretless assault guns, much favoured during World War II by the German and Soviet armies, also virtually disappeared.

      The general trend among the remaining self-propelled guns was either toward lightly but completely armoured models with guns mounted in turrets capable of all-around traverse, like most tanks, or toward partially armoured models that were essentially tracked chassis with guns mounted on top. Examples of the completely armoured self-propelled guns were the U.S.-built 155-millimetre M109 self-propelled howitzer (used not only by the U.S. Army but also by several others), the French 155-millimetre GCT, and the Soviet 122-millimetre SO-122 and 152-millimetre SO-152. Partially armoured models were represented by the U.S.-built M107 175-millimetre gun and M110 8-inch howitzer and by the Soviet 203-millimetre SO-203.

Armoured personnel carriers
      After World War II, armoured personnel carriers became the next most important armoured vehicle after battle tanks. Though a few experimental models were built in Britain at the end of World War I, development of armoured carriers did not really begin until they were adopted for the panzer division infantry at the beginning of World War II. Germany's example was quickly followed by the United States, which, by the end of the war, had produced 41,000 carriers. Both the German and U.S. carriers of World War II were of the half-track type and provided only light protection; nevertheless, they represented a major advance on the earlier method of transporting infantry into battle in unarmoured trucks. Moreover, the panzer grenadiers used them effectively as combat vehicles and fought from them on the move, thus greatly increasing the mobility of infantry on the battlefield.

Tracked carriers
      In the postwar era the U.S. Army led in developing fully tracked carriers with all-around armour protection. The first postwar carrier was the large M44. This was followed in 1952 by the M75, which had a similar box body but carried 12 instead of 27 men. A few M75s were used successfully during the Korean War, and it became the first tracked armoured carrier to be used in large numbers.

 In 1955 the M75 began to be replaced by the M59, which was similar in appearance but was less expensive and could swim across calm inland waters. In 1960 came the M113, which had a lower silhouette and was considerably lighter, owing partly to the use of aluminum armour. The M113 was in fact the first aluminum-armoured vehicle to be put into large-scale production. After its appearance, several other armoured carriers, light tanks, and self-propelled guns were built with aluminum armour. Within 30 years more than 76,000 M113 carriers and their derivatives had been produced, making them the most numerous armoured vehicles outside the Soviet bloc. M113 carriers were used extensively in the Vietnam War, often as combat vehicles, although they were not designed for this and were at a disadvantage in spite of the addition of roof-mounted machine guns with shields.

Infantry fighting vehicles
      The first attempt to produce a tracked armoured carrier from which the infantry could fight to some extent was represented by the French AMX-VTT of 1958. A further step in this direction was taken by the West German army with the HS-30, which had a turret with a 20-millimetre cannon. The most significant advance was represented by the Marder, which was produced for the panzer grenadiers of the West German army during the 1970s, and the BMP, mass-produced for the Soviet armoured infantry from the mid-1960s. The Marder weighed 29.2 tons and carried nine men in addition to mounting a turret with a 20-millimetre cannon. The BMP-1 weighed 13.5 tons and could carry up to 11 men. It was armed with a turret-mounted, low-performance 73-millimetre gun, while the BMP-2 was armed with a high-velocity 30-millimetre cannon; both versions carried externally mounted antitank guided missiles.

      Another tracked armoured infantry vehicle was the U.S. M2 Bradley Infantry Fighting Vehicle, introduced in the 1980s. This 10-man vehicle weighed 22.6 tons and had a two-man turret with a 25-millimetre cannon and a TOW antitank missile launcher. Its British equivalent was the Warrior Mechanized Combat Vehicle, produced since 1986. This was also a 10-man vehicle of 24.5 tons with a 30-millimetre cannon in a two-man turret.

 In addition to tracked armoured carriers or infantry fighting vehicles, which were intended to cooperate closely with tanks, most armies also developed wheeled armoured carriers for more general use. Examples included the VAB of the French army and the BTR-60, -70, and -80 of the Soviet army.

Richard Marian Ogorkiewicz

Additional Reading
Tanks and armoured vehicles are discussed in Richard M. Ogorkiewicz, Armour: A History of Mechanized Forces (1960, reissued as Armoured Forces: A History of Armoured Forces and Their Vehicles, 1970); and Design and Development of Fighting Vehicles (1968), on the technical aspects. The history of various types of vehicles from World War I to the end of World War II is presented in Duncan Crow (ed.), AFVs of World War One (1970), British AFVs, 1919–40 (1970), British and Commonwealth AFVs, 1940–46 (1971), American AFVs of World War II (1972), and Armored Fighting Vehicles of Germany: World War II (1973). Peter Chamberlain and Hilary L. Doyle, Encyclopedia of German Tanks of World War Two: A Complete Illustrated Directory of German Battle Tanks, Armoured Cars, Self-Propelled Guns, and Semi-tracked Vehicles, 1933–1945 (1978), provides a comprehensive pictorial record. Duncan Crow (ed.), Modern Battle Tanks (1978), focuses on the period between 1950 and 1970. For particular types of tanks, see Walter J. Spielberger, From Half-Track to Leopard 2: The Complete Illustrated History of the Krauss-Maffei Ordnance Department (1979; originally published in German, 1979); John Milsom, Russian Tanks, 1900–1970: The Complete Illustrated History of Soviet Armoured Theory and Design (1970); and R.P. Hunnicut, Sherman: A History of the American Medium Tank (1978), Patton: A History of the American Main Battle Tank (1984), and Firepower: A History of the American Heavy Tank (1988). For current information on developments in technology, see Jane's Armour and Artillery (annual) and Jane's Armoured Fighting Vehicle Systems (annual).Richard Marian Ogorkiewicz

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Universalium. 2010.

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