四號坦克
Bombing raids on the Alkett factory resulted in significant drops in StuG III production in November 1943. To make up for this loss of production, Krupp displayed a substitution StuG on a Panzer IV chassis to Hitler on 16–17 December 1943. From January 1944 onwards, the StuG IV, based on the Panzer IV chassis and with a slightly modified StuG III superstructure, entered production.