Heavy tank

Heavy tank
A Soviet IS-3 heavy tank
Type	Tank
Service history
In service	1916 – ca. 1990s (early part of)

A heavy tank was a subset of tank that provided better armour protection as well as equal or greater firepower than tanks of lighter classes, at the cost of mobility and manoeuvrability and, particularly, expense.

The origins of the class date to World War I and the very first tanks; designed to operate in close concert with the infantry and facing both artillery and the first dedicated anti-tank guns, early tanks had to have enough armor to allow them to survive on no man's land. As lighter tanks were introduced, the larger designs became known as heavies. The same basic role remained into World War II, with the British referring to them as infantry tank indicating this close support role.

As tank combat became more common, especially tank-vs-tank, the heavies also became platforms to mount very powerful anti-tank guns, and the role of the heavies began to change. By the end of the war they were a primary class, used both for dealing with heavy fortifications as well as forcing its way through enemy tank formations. They were also known as breakthrough tanks, indicating their purpose of spearheading the attack. In spite of this, in practice they have been more useful in the defensive role than in the attack.

The emergence of the main battle tank spelled the end of the heavy tank as a separate class, although a number of post-war examples were produced. These were generally gone by the 1960s.

There was not a consistent line distinguishing heavy tank from medium tanks. The definition only became apparent during the interwar/war period, when the Germans adopted the "blitzkrieg" method of warfare and the heavy tanks, mostly infantry/heavy tanks at the time, were too slow to keep up, and where light tanks (or cruiser tanks) were not sufficiently armoured. Ultimately the line was drawn by a vehicles weight in conjunction with its operational capability, particularly its armament.

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. But the greatest drawback is cost which translates into production quantities and/or design. The German Tiger I, for example, had similar speed and better terrain-handling characteristics when compared to the significantly lighter Panzer IV medium tank, albeit at the cost of low reliability and only 1,355 were produced compared to 8,800 Panzer IV and over 59,000 Soviet T-34 and over 45,000 American M4 Sherman medium tanks. This case repeated itself in the operational use of the Tiger II of which only 492 were produced.