An anti-tank gun is a form of artillery designed to destroy tanks and other armored fighting vehicles, normally from a static defensive position. The development of specialized anti-tank munitions and anti-tank guns was prompted by the appearance of tanks during World War I. To destroy hostile tanks, artillerymen often used field guns depressed to fire directly at their targets. However, this practice expended too much valuable ammunition and was of increasingly limited effectiveness as tank armor became thicker. The first dedicated anti-tank artillery began appearing in the 1920s and by World War II was a common appearance in many European armies. In order to penetrate armor they fired specialized ammunition from longer barrels to achieve a higher muzzle velocity than field guns. Most anti-tank guns were developed in the 1930s as improvements in tanks were noted, and nearly every major arms manufacturer produced one type or another.
Anti-tank guns deployed during World War II were often manned by specialist infantry rather than artillery crews, and issued to light infantry units accordingly. The anti-tank guns of the 1930s were of small caliber; nearly all major armies possessing them used 37mm ammunition, except for the British Army, which had developed the 40mm Ordnance QF 2-pounder. As World War II progressed, the appearance of heavier tanks rendered these weapons obsolete and anti-tank guns likewise began firing larger and more effective armor-piercing shot. The development of the compact hollow charge projectile permanently altered anti-tank warfare, since this type of ammunition did not depend on a high muzzle velocity and could be fired from low-recoil, man-portable light weapons, such as the Panzerfaust and the American series of recoilless rifles.
Although a number of large caliber guns were developed during the war that were capable of knocking out the most heavily armored tanks, they proved expensive and difficult to conceal. The later generation of low-recoil anti-tank weapons, which allowed projectiles the size of an artillery shell to be fired from the shoulder, was considered a far more viable option for arming infantry. Recoilless rifles replaced most conventional anti-tank guns in the postwar period; nevertheless, the development of new anti-tank guns exhibiting similar low-recoil performance continued until the late 1950s in France, Belgium, and the Soviet Union. A few Soviet designs saw combat well into the 1980s. The People's Republic of China was still producing large caliber anti-tank guns as late as 1988.
The first specialized anti-tank weaponry consisted of anti-tank rifles. These emerged from the mixed results of deploying field artillery against tanks during World War I, and the need to produce a more economical weapon to destroy them. Most anti-tank rifles were over 1.3m in length, however, and difficult for infantrymen to operate in the confines of their trenches. They could penetrate a tank's armor at long range, but without explosive firepower, often failed to cause catastrophic damage, kill or even seriously injure the crew, or disable the tank. A number of infantry support guns designed to defeat hard targets such as fortified machine gun emplacements were used as makeshift anti-tank weapons, including the French Canon d'Infanterie de 37 modèle 1916 TRP. The 3.7 cm Tankabwehrkanone 1918 im starrer Räder-lafette was probably the first dedicated anti-tank gun in service. However, its gun barrel was based on an earlier Hotchkiss 5- barrelled rotary-cannon. The 3.7 cm TAK 1918 was designed and built for the Imperial German Army in 1918. The 3.7 cm Pak 36 which first appeared in 1928 was probably the first purpose built anti-tank gun. Weighing some 160 kg, the Pak 36 could inflict a catastrophic kill on a tank rather than merely penetrating its armor plate. Towed guns similar to the Pak 36 were the only anti-tank weapon issued to European armies during the 1930s, and a number of influential designs proliferated, such as the Böhler gun. By the late 1930s, anti-tank guns had been manufactured by companies in Germany, Austria, France, Czechoslovakia, Belgium, Great Britain, Denmark and Sweden. A few countries, such as the Soviet Union, also manufactured foreign designs under license.
At the outbreak of World War II, most armies were fielding light anti-tank guns firing 3.7 cm (37mm) ammunition. The guns were usually mounted on two-wheeled carriages so they could be towed into position, then withdrawn and repositioned rapidly. Since they weighed only a few hundred pounds on average, they could also be manhandled into position. All fired high-explosive and solid armor-piercing shot effective at relatively medium range, and an increasing number were manufactured with protective gun shields in addition to a split rail mounting. They were able to destroy tanks fielded by both sides during the first two years of the war, but soon proved impotent against the heavier tank armor that debuted in 1940. Introducing improved ammunition and increasing muzzle velocity initially helped compensate for their mediocre performance, but it was clear that small caliber anti-tank guns would soon be overtaken by yet more heavily armored tanks. Medium caliber guns in the 40mm to 50mm range began to appear, some of which simply utilised rebored 37mm barrels. Although they too were soon approaching obsolescence, most remained in use with infantry units until the end of the war. Anti-tank guns remained ineffective against sloped armor, as demonstrated by an incident in 1941 when a single Soviet T-34 tank was hit more than 30 times by a battalion-sized contingent of German 37mm and 50mm anti-tank guns. The tank survived intact and was driven back to its own lines a few hours later. This helped earn the Pak 36 the moniker of Panzeranklopfgerät ("tank door knocker") because its crew simply revealed their presence and wasted their shells without damaging the T-34's armor. Anti-tank gunners began aiming at tank tracks, or vulnerable margins on the turret ring and gun mantlet, rather than testing their lighter cannon against bow and turret armor. These difficulties resulted in new types of ammunition being issued, namely high-explosive anti-tank (HEAT) and armor-piercing discarding sabot (APDS) projectiles.
Towards the end of World War II, armor plating became still thicker, with tanks such as the Tiger II being fitted with armor over 100mm in thickness, as compared to the 15mm more typical in 1939. This prompted the development of a third generation of anti-tank guns, large caliber pieces in the 57mm to 100mm range. The British Army adopted the Ordnance QF 6-pounder and Ordnance QF 17-pounder, which were then considered great advances in firepower, and the Wehrmacht fielded the even larger 7.5 cm Pak 41 and 8.8 cm Pak 43. While the early 37mm anti-tank guns were easily concealed and moved; the large caliber weapons available late war required equally large vehicles to tow them into place and were difficult to conceal, dig in, withdraw, or reposition. By 1945, large anti-tank guns had become almost impractical in their role, and their size and weight was considered a liability. They were also expensive to produce and although they were capable of defeating the most formidable of opponents, most tank units still consisted of less heavily armoured models that remained vulnerable to less expensive and more practical guns as well. Many heavy anti-tank guns were issued, at least initially, on the divisional level but gradually made their way to individual infantry battalions.
Meanwhile, the effect of very compact hollow charge warheads was being noted and a number of countries began producing man-portable anti-tank weapons utilizing this ammunition. The development of man-portable, shoulder-fired anti-tank rocket launchers began in 1941; most could be reloaded, but a few such as the German Panzerfaust were fired from disposable tubes. Unlike anti-tank guns, their light weight made them easily portable by individual infantrymen on the battlefield, and they offered similar degrees of firepower whilst being quicker and cheaper to produce.
Towed anti-tank guns disappeared from most Western countries, such as the United States, after World War II, to be replaced by shoulder-fired rocket launchers, recoilless rifles, and eventually, guided anti-tank missiles.
At the end of the war, German engineers had proposed a new large caliber anti-tank gun that used less propellant than a rocket or recoilless weapon, yet fired similar compact hollow charge shells. German forces subsequently fielded the 8 cm PAW 600, which was an extremely lightweight, low pressure weapon still able to fire the same ammunition types as higher velocity anti-tank guns. In the 1950s, this idea was revived by a Belgian firm, Mecar, which subsequently improved on the concept and developed a low pressure, smoothbore 90 mm anti-tank gun. Because of its low recoil forces and light construction, the gun was particularly useful for being mounted on armored cars or small gun carriages. Its design inspired the lightly rifled French DEFA D921 anti-tank gun, which fired fin-stabilized shells and was available on a towed carriage or as a vehicle mount. It was later mated to the AML-90 and EBR series of French armored cars. The Soviet Union also adopted a similar design at around the same time, the 100 mm T-12 anti-tank gun, which was smoothbore and fired fin-stabilized shells. Switzerland developed a postwar 90 mm anti-tank gun of its own, the Pak 50/57, firing shells with an even lower velocity than the Mecar or DEFA guns. Apart from the T-12, which utilized APDS rounds, these weapons could only use HEAT shells for armor-piercing purposes. France did introduce an APFSDS shell for the DEFA D921 at some point in the 1980s. The last country known to have produced a dedicated anti-tank gun was the People's Republic of China, in 1988. The Chinese gun was known as the Norinco Type 86 and was probably manufactured as a replacement for the ageing Soviet-sourced T-12.
Anti-tank guns continued to be used in a number of conflicts around the world, such as the Six-Day War and the South African Border War. Soviet anti-tank guns in particular were exported to at least eighteen other countries after being retired from service and have continued to see action.
Although still being drawn by horses or towed by trucks, towed anti-tank guns were initially much lighter and more portable than field guns, making them well-suited to infantry maneuvers. However, as their size and caliber increased, the guns likewise became increasingly heavy and cumbersome, restricting their role to static defense. In consequence, during World War II, both sides were compelled to make anti-tank guns self-propelled, which greatly increased their mobility.
The first self-propelled anti-tank guns were merely belated attempts to make use of obsolete tanks, such as the Panzerjäger I, which was a 4.7 cm Pak (t) mated to a Panzerkampfwagen I chassis. The trend continued with older tanks, which were available in large numbers for conversions to self-propelled guns when they were replaced by heavier and better-armed tanks. Although just a makeshift solution, these initial experiments proved so successful they spawned an entire class of new vehicles: dedicated tank destroyers.
Tank destroyers offered some advantages over towed anti-tank guns, since a static gun emplacement sacrificed concealment and surprise after firing the first shot; however, the same gun mounted on a tracked or wheeled chassis could open fire and throw a tank formation into substantial disarray before quickly withdrawing to repeat the same tactic elsewhere. The introduction of tank destroyers also put an end to the traditional tactic of suppressing anti-tank gun batteries with heavy artillery bombardments, as their crews were now well-protected under armor. They were not without their own series of disadvantages, however, namely presenting a much larger target than a towed gun, the added responsibilities of vehicle maintenance and logistical support, and the limited spaces in which the crew had to operate and stow all their available ammunition.
By the end of the war, dedicated tank destroyers had been superseded by tanks, which were just as effective at destroying other tanks, and there was little incentive to continue their separate development. Nevertheless, much like towed anti-tank guns, they were widely exported and were still in service with several armies in the late twentieth century.