Since infantry tanks were to work at the pace of infantry units which would be attacking on foot, high speed was not a requirement and they were able to carry heavier armour. The first two purpose-designed infantry tanks, the A.11 Matilda Mark I armed with a heavy machine-gun and A.12 Matilda Mark II with a heavy machine gun and 2-pounder anti-tank gun. The Mark I had been ordered in 1938, but it had become clear that a better-armed tank would be needed and the Mark II, was already under design and would be ordered in mid-1938.