Development of the Panzer III began in the mid-1930s with the aim to make it the backbone of the armoured battalions of the Wehrmacht alongside a smaller number of heavier tanks Panzer IV Initially armed with a 37mm cannon the Panzer III moved rapidly to a 50mm cannon & in the upgraded versions Ausf M & L to the 75 24 gun with 64 rounds already used on the Panzer IV Production ceased in August 1943