Tank classification

An early division in the definition of roles was between infantry tanks intended to focus on supporting infantry in the assault, and cruiser tanks intended for classic cavalry missions of exploitation, screening and reconnaissance.

As World War II progressed, the separation of "infantry" and "cruiser" roles generally disappeared and the "universal tank" started to take over.

Classification has always been determined by the prevailing theories of armoured warfare, which have been altered in turn by rapid advances in technology.

All main battle tanks are typically armed with weapons with similar characteristics but some may be armoured more than others.

The works were further explored by Heinz Guderian in the development of German tank doctrine and Blitzkrieg for the opening stages of World War II.

Infantry tanks proved capable in this new role however, and the designation was rarely applied outside of experimental production.

Towards the end of the war, increases in tank engine power started to create the possibility of multi-role vehicles.

Heavy tanks were largely withdrawn from service as medium multi-role vehicles offered similar capability with less of the weight-based constraints.

Some heavy tanks had large-calibre, low-velocity, anti-infantry bunker-busters, and some had high-velocity anti-tank guns.

They now have other meanings than just weight, including relation to gun size, the amount of armour, and, most importantly, tactical role.

After World War II, less expensive armoured cars and more specialised tracked vehicles gradually took over the roles of light tanks.

The ultimate in mobility, firepower, and protection were rolled into the main battle tank (MBT).

[3] In World War I, the first tank, the 28-long-ton (28 t; 31-short-ton) British Mark I, was designed for supporting infantry by crossing trenches and attacking machine-gun posts.

[4] In World War 2, Light, Medium, and Heavy tank applications to different roles were incorporated into doctrine.

A variety of super-heavy tanks were also designed during World War II, although none ever saw combat or construction due to their impracticality.

The British retained some light tanks from the interbellum period, but otherwise moved to a new role based classification scheme.

Heavy tanks grew to the point of being logistically problematic, such as the Conqueror and IS-3, while the MBT became capable of filling their battlefield role in a comparatively Medium form-factor.

In most cases, the Heavy tanks grew so large that they could not be transported by rail, and could not be supported by common bridges.

British and Soviet tacticians up to the time of the Second World War classified tanks into three major roles: infantry, light, and cavalry.

Cavalry or "cruiser" tank units were meant to exploit breakthroughs and fight other armoured formations.

This was made possible as increased engine power provided the capability to sufficiently armour a cruiser tank, the Centurion, to undertake both roles.

In Germany, the ideas of Heinz Guderian established the need for unified tank formations, but with a mixture of armaments for differing roles.

In the United States, doctrine evolved so that the main purpose of the tank was to provide infantry support and exploitation of breakthroughs.

There were those within the US Army which advocated a more modern force with tanks in the cavalry role, but their suggestions were not put into place by the time of the US's entry into World War II.

Its main purpose would have been to clear the battlefield of obstacles, suppress or destroy defenders, and protect the infantry on their advance into and through enemy lines by giving mobile overwatch and cover.

In order to give them the required speed, cruiser designs sacrificed armour compared to the infantry tanks.

Advances such as the British-designed Chobham armour limit the effectiveness of weaker HEAT rounds, but the vulnerability still remained.

These vehicles are less obviously influenced by wartime templates (the Chieftain, for example), weighing as much as a World War II heavy tank and possessing far greater firepower and armour, while retaining the mobility of the previous Centurion design.

Unmodified tanks can be fitted with equipment, such as mine-clearing ploughs, to give them ancillary roles.