The infantry tank was a concept developed by the British and French in the years leading up to World War II. Infantry tanks were tanks designed to support the infantry in the attack. To achieve this they were generally heavily armoured to allow them to operate in close concert with infantry even under heavy gun fire. The extra armouring came at the expense of speed, which was not an issue when supporting relatively slow moving foot soldiers (infantry).
Once the infantry tank-supported attack had broken through heavily defended areas in the enemy lines, other tanks such as cruiser tanks or light tanks, were expected to exploit their higher speed and longer range to operate far behind the front in order to cut lines of supply and communications.
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