US Tank Destroyers
Contributed by Michael Burnside
Tanks were conceived as a means of defeating entrenched infantry. The concept of using tanks to destroy other tanks took time to evolve. At the beginning of World War II most tanks were still designed for the purpose of supporting attacks against infantry. In World War I, tank verses tank encounters were a rarity. In World War II, such encounters became fairly common. As the threats against tanks evolved, the amount of armor they had increased. It slowly became apparent that the weapons that tanks were using against infantry were inadequate when it came to dealing with other tanks. A slow velocity high explosive shell works well for bombarding enemy troop positions, but has little chance of defeating a well armored target.
As tanks became more common on the battlefield, militaries began to search for means by which to stop them and protect their infantry.
Hand held anti-tank weapons showed promise, but even by the end of the war, most of these were not powerful enough to destroy a tank head on and lacked range. They were quite useful in close quarter battles, but nearly suicidal to use in the open.
Artillery fire can be very effective against armor assets, but is difficult to direct onto a mobile target. Using artillery as direct fire was found to be far more accurate and from this concept towed anti-tank (AT) guns evolved. However AT crews had little protection from enemy fire and the AT guns' lack of mobility made them difficult to withdraw or move into position quickly. The obvious solution to this was to mount an AT gun on a mobile platform, like a tank. Yet tactical doctrine was a bit slow to catch up to this realization. The tank was still often thought of as an instrument of infantry support, not as an anti-tank element. Additionally, tanks are expensive. Designers were looking for a low cost means of defeating enemy tanks. One solution they came up with was the tank destroyer.
The first dedicated US tank destroyer was the M10 Gun Motor Carriage. The name plainly stated what the vehicle was intended to be despite what it appeared to be. The vehicle appeared to be a tank. It had a fully operational three hundred and sixty degree turret which mounted a 76mm high velocity gun. But the M10 was not a tank. It didn't have the armor to qualify as a tank. In the designer's mind, the M10 was a towed anti tank gun mounted on a pair of tank treads. On paper it solved what appeared to be the anti-tank gun's primary drawback, lack of mobility. However mounting an anti-tank gun on a tank platform gave the gun a higher profile thus amplifying its other drawback, vulnerability.
The M10's appearance often meant that it was misused by ground commanders. It looked like a tank so it got used as a tank, often with disastrous results due to the vehicle's thin armor.
The US chose to mount full turrets on their tank destroyers but used open top designs. This saved on weight, cost, and gave more room for the crew to work with the larger gun that these vehicles mounted. Choosing to use an open top turret meant that the vehicle's crew was extremely vulnerable to any kind of top down attack be it artillery or infantry. These armored assets were vulnerable to snipers and grenades. The belief that the larger guns could not be mounted on more traditional turrets was soon proven wrong by the British Firefly. Many US tanks were eventually upgraded to the same 76mm gun that the M10 tank destroyer carried giving those tanks the same firepower as the tank destroyer but without the horrible vulnerability.
US tank destroyer doctrine envisioned large tank destroyer formations using their superior mobility to flank and destroy enemy armor. In reality, it was difficult to coordinate such actions.
The speed advantage gained by sacrificing armor never really outweighed the disadvantage of having so little protection. Any mid to late war German tank gun could destroy a US tank destroyer with a single shot from any angle. Meanwhile US tank destroyers had to flank their opponents, even enemy tank destroyers, if they were to have any hope of success.
After the war the US viewed the tank destroyer concept as a flawed idea. Modern US main battle tanks are designed for the principle purpose of engaging enemy armor, not infantry.