A self-propelled anti-tank gun, or '''tank destroyer''', is a type of [[armoured fighting vehicle]]. Tank destroyers are used primarily to provide [[anti-tank]] support in combat operations but do not fit all the criteria of a [[tank]]. They may mount a high-velocity anti-tank gun but have an open turret, no turret at all or run on wheels instead of tracks.
Vehicles which carry an [[anti-tank guided missile]] launcher are referred to as ATGM carriers.

Tank destroyers cannot fulfil the many roles of tanks; they are much less flexible, and usually lack a strong anti-infantry capability. A common feature of a tank destroyer is the absence of a turret, and compared to tanks, an even stronger disposition for heavy frontal armor (compared to side and rear armor). However, as a result of having no turret and fewer parts, tank destroyers are much less expensive to manufacture.

Gun-armed tank destroyers have been largely supplanted by the more general-purpose tanks since [[World War II]], but lightly-armoured ATGM carriers are used for supplementary long-range antitank capabilities.

== World War II ==
[[Image:ISU-122 skos RB.jpg|thumb|350px|Soviet [[ISU-122]] tank destroyer with [[Polish Army]] markings]]

Dedicated antitank vehicles made their first major appearance in the Second World War, as combatants developed effective armoured vehicles and tactics.

These tank destroyers fell broadly into two categories. Some were designed to be faster and cheaper than medium tanks while still able to destroy heavy armour at long range. Some of these designs were clearly experiments rushed into production. The second design strategy was to create heavily-armoured vehicles that were more effective in tank-versus-tank combat than enemy tanks.

===German designs===
The first [[Nazi Germany|German]] tank destroyers were the ''[[Panzerjäger]]'' ("tank hunters") which took an existing anti-tank gun and put it on a convenient chassis to give mobility. For instance, the German [[Panzer I]] light tank was obsolete before the war even started, with only thin armor and machine guns for armament. It was put into battle during the invasion of [[Poland]], where it was found to be a deathtrap. Before the subsequent [[Battle of France|invasion of France]], 202 were rebuilt as the [[Panzerjäger I]] self-propelled [[Skoda]] {{nowrap|47 mm}} anti-tank guns taken from [[Czechoslovakia]]. Similarly [[Panzer II]] tanks were used on the eastern front; captured Soviet {{nowrap|76.2 mm}} anti-tank guns were mounted on [[Panzer II]] chassis, producing [[Marder II]] anti-tank guns. The most common mounting was a German {{nowrap|75 mm}} anti-tank gun on the Czech [[Panzer 38(t)]] chassis to produce the [[Marder III]]. The Panzerjäger series continued up to the {{nowrap|88 mm}} equipped [[Nashorn]].

Although the Panzerjager carried effective weapons they were generally lacking in protection for the crew having thinly armoured open-topped superstructures and used older designs of chassis. They were to be followed by the ''[[Jagdpanzer]]'' '("hunting tanks") which mounted the gun in better superstructures – sacrificing the wider traverse capability of the anti-gun carriage for good armour protection. The best of the designs is considered to be the [[Jagdpanther]] which put an {{nowrap|88 mm}} gun in one of the later tank chassis, that of the [[Panther tank]]. The Germans became side-tracked into production of large numbers of tank-destroyers because they could be produced more cheaply than full tanks. The Jagdpanzers were better suited to defense than attack because of their limited traverse and the later designs such as the [[Jagdtiger]] (of which just under 50 were built by May 1945) were heavy and consequently less manoeuvrable albeit extremely hard to defeat.

The most successful German tank destroyer wasn't supposed to be a tank destroyer at all; it was the [[Sturmgeschütz III]].

===Soviet===

As with the Germans, the [[Soviet Union|Soviet]] designs mounted anti-tank guns, with limited traverse in turretless hulls. The results were smaller, lighter, and simpler to build than tanks, but could carry larger guns. This design methodology was used by both the USSR and the Germans to provide heavier anti-tank capability at lower cost, during the rapid up-armoring of all AFVs that took place during the war. The Soviets produced the {{nowrap|85 mm}} [[SU-85]] and {{nowrap|100 mm}} [[SU-100]] self-propelled guns based on the same chassis as the [[T-34]] medium tank, as well as the {{nowrap|122 mm}} [[ISU-122]] and {{nowrap|152 mm}} [[ISU-152]] which shared components with the [[IS-2]] heavy tank and was nicknamed ''Zveroboy'' ("beast killer") for its ability to destroy German Tigers, Panthers and Elephants. In 1943, the Soviets also shifted all production of light tanks like the [[T-70]] to much simpler and better-armed [[SU-76]] self-propelled guns, which used the same drive train.

=== United States ===
{{main|Tank destroyer battalion (United States)}}
[[United States Army|U.S. Army]] and derivative [[United Kingdom|British]] designs were very different in conception. U.S. doctrine was based on the perceived need to defeat German [[blitzkrieg]] tactics, and U.S. units expected to be faced with large numbers of German tanks attacking on relatively narrow fronts. In actual practice, such attacks rarely happened; indeed, throughout the war only one battalion ever fought in an engagement quite like that which had originally been envisaged. The Tank Destroyer Command eventually numbered over 100,000 men and 80 battalions equipped with 36 tank destroyers or towed anti-tank guns each.

The U.S. tank destroyer designs were intended to be very mobile and heavily armed. Most retained a turret, but left it open on top both to save weight and to accommodate a larger gun. The earliest expedient design was an [[M3 Half-track]] mounting an M1897 {{nowrap|75 mm}} gun in a limited-traverse mount, and called the [[M3 GMC|75-mm GMC M3]]. Another, considerably less successful, early design mounted a 37-mm antitank gun in the bed of a Dodge 3/4-ton truck - the [[M6 Fargo|37-mm GMC M6]]. The larger guns required a counterweight at rear of the turret, which can be seen on designs like the 3-inch gun [[M10 Wolverine|3in Gun Motor Carriage M10]] and the [[M36 Jackson|90mm Gun Motor Carriage M36]]. The [[M18 Hellcat|76mm Gun Motor Carriage M18]] came closer to the U.S. ideal; the vehicle was very fast, small, and mounted a {{nowrap|76 mm}} gun in a turret. Of these, only the {{nowrap|90 mm}} gun of the M36 proved to be effective against the Germans' larger armored vehicles at any significant range. The open top and light armour made these tank destroyers particularly vulnerable to anything greater than small-arms fire, which ensured that in a direct fight they were no match for tanks. As the number of German tanks encountered by American forces steadily decreased throughout the war, most battalions were split up and assigned to infantry units as support vehicles, fighting as [[assault guns]] or as local anti-tank reserves.

===United Kingdom ===
On the whole, the British army did not subscribe to the Tank Destroyer concept, preferring instead to design tanks armed with bigger guns. Although flawed in many other respects, contemporary British armour doctrine recognized the inevitability of tank versus tank combat and the Army strove to arm their tanks with the most powerful anti-tank gun available at the time.

Anti-tank guns were the domain of the [[Royal Artillery]] rather than the [[Royal Armoured Corps]] and anti-tank gunned vehicles particularly anti-tank self-propelled guns such as the [[Deacon (artillery)|Deacon]] and [[Archer (tank destroyer)|Archer]] were their preserve.

The self-propelled guns that were built in the "Tank Destroyer" mould came about through the desire to field the formidable [[QF 17 pounder]] anti-tank gun and simultaneous lack of suitable tanks to carry it. As a result they were of a somewhat extemporized nature. Mounting the gun on the [[Valentine tank]] chassis gave the Marder-like Archer. The 17 pounder was also used to equip the US supplied [[M10 Wolverine]] to produce the ''Achilles''. Another attempt to produce a specialist anti-tank vehicle was to fit the 17 pounder to the Cromwell chassis to give [[Cruiser Mk VIII Challenger|Tank, Cruiser, Challenger (A30)]] and its near open-topped variant ''Avenger''. The latter delayed until post war before entering service.

The closest the British came to developing an armoured Tank Destroyer in the vein of the German Jagdpanzers or Russian ISU series was the Churchill 3 inch Gun Carrier - a [[Churchill tank]] chassis with a boxy superstructure in place of the turret. The design was rejected in favor of developing a 17 pounder armed Cromwell tank variant ultimately leading to the [[Comet tank]]

By 1944, a number of the "basic" [[Sherman tank|Shermans]] in British use were being converted to [[Sherman Fireflies]] by adding the potent [[QF 17 pounder]] gun — giving each platoon of Shermans a dedicated anti-tank tank.

== Post–World War II development ==
In the face of the Warsaw Pact, a general need for extra firepower was identified. In the 1950s, the UK produced the [[FV 4101 Charioteer]] to beef up the tank regiments, mounting a 20 pounder gun in an oversize turret on the Cromwell tank hull — it lacked the all round capability of the [[Centurion tank]]. It was followed by the [[Conqueror tank]] which carried a {{nowrap|120 mm}} gun. In the late 1960s, Germany developed the [[Kanonenjagdpanzer]], essentially a modernized WWII Jagdpanzer mounting a {{nowrap|90 mm}} gun. As Soviet designs became more heavily armoured, the {{nowrap|90 mm}} gun became ineffective and the Kanonenjagdpanzers were retrofitted for different roles or retired.

With the development of flexible [[Anti-tank guided missile]]s, which were capable of installation on almost any vehicle in the 1960s, the concept of the tank destroyer has waned.
With the weight of main battle tanks growing to the forty to seventy-tonne range, airborne forces were unable to deploy reasonable antitank forces. The result was a number of attempts to make a light vehicle, including the conventional [[ASU-85]], the recoilless rifle–armed [[Ontos]], and missile-armed [[Malkara missile#FV1620 Humber Hornet|Hornet Malkara]] armoured car and [[M551 Sheridan|Sheridan]] light tank.

==Modern tank destroyers==
Many forces' [[IFV]]s carry [[Anti-tank guided missile|ATGMs]] in every infantry platoon, and [[attack helicopter]]s have also added antitank capability to the modern battlefield. But there are still dedicated antitank vehicles with very heavy long-range missiles, and ones intended for [[Airborne forces|airborne]] use.

[[Image:NM142 x 3.jpg|thumb|250px|A Norwegian antitank platoon equipped with [[NM142]] TOW missile launchers]]
There have also been dedicated antitank vehicles built on ordinary [[armoured personnel carrier]] or [[armoured car]] chassis. Examples include the U.S. [[M901 ITV|M901 ITV (Improved TOW Vehicle)]] and the [[Norway|Norwegian]] [[NM142]], both on an [[M113]] chassis, several [[Soviet]] ATGM launchers based on the [[BRDM]] reconnaissance car, and the [[Germany|German]] [[Raketenjagdpanzer]] series built on the chassis of the [[HS 30]] and [[Marder (IFV)|Marder]] IFV.

A [[United States Army|US Army]] mechanized infantry battalion has four infantry companies with TOW missile–armed [[M2 Bradley|Bradley IFVs]] and can bring a large concentration of accurate and lethal fire to bear on an attacking enemy unit that uses AFVs.

Missile carrying vehicles however are referred to as [[anti-tank guided missile]] (ATGM) carriers instead of tank destroyers. In modern times a tank destroyer is an armored fighting vehicle with a large caliber cannon which is not a tank because it does not fit into all the criteria that makes a tank a tank. A tank is an armored vehicle which runs on tracks and has a large caliber direct fire cannon in a 360 degrees rotating enclosed turret.
This makes large caliber gun vehicles that have an open turret ([[M36 Jackson]]), do not have a turret ([[S-tank|STRV-103]], [[Kanonenjagdpanzer]]) or which run on wheels instead of tracks ([[Centauro]], [[PTL02]]) tank destroyers.

Some gun-armed tank destroyers continue to be used. The German army had specialized [[Kanonenjagdpanzer]], similar in design to the WWII tank destroyers, from the mid-1960s until the 1980s. In the same time frame, [[Sweden]] developed armoured forces: the [[S-tank|STRV-103]], armed with a {{nowrap|105 mm}} cannon (however its actual combat role is uncertain). The [[People's Republic of China]] has developed the tracked PTZ89 and the wheeled [[PTL02]] tank destroyers. PTZ89 is armed with a {{nowrap|120 mm}} smoothbore cannon while PTL02, developed by NORINCO for the PLA new light (rapid reaction) mechanised infantry divisions, carries a {{nowrap|100 mm}} rifled gun. PTL02 is built on the 6×6 wheeled chassis of the [[WZ551]] APC.
[[Italy]] and [[Spain]] use the Italian-built [[Centauro]], a wheeled tank destroyer with a {{nowrap|105 mm}} cannon. The gun-armed tank destroyer may possibly see revival in the US Army through the introduction of the [[Stryker]], more specifically, the [[Mobile Gun System|M1128 Mobile Gun System]], a Stryker variant armed with a {{nowrap|105 mm}} cannon which has remote control and autoloading capabilities.

Ironically, modern tank destroyers, due to being more mobile than tanks, are more suitable for low-intensity and urban warfare that are being fought in the War on Terrorism. Some are considering the possibility of replacing tanks with lightweight, wheeled tank destroyers to deal with elusive insurgents encountered in both Iraq and Afghanistan. originally, the Canadian Forces had considered replacing their aging [[Leopard 1]] tanks with the Stryker Mobile Gun System, essentially creating a tank destroyers-only force but with the use of IED that are capable of destroying Strykers, had opted to buy [[Leopard 2]] tank for now.

== References ==
* Harry Yeide, (2005) ''The Tank Killers: A History of America's World War II Tank Destroyer Force.'' Havertown, PA: Casemate. ISBN 1-932033-26-2

[[Category:Tank destroyers|*]]

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