In 1942 the Waffenamt (Ordnance Department) saw a need for self-propelled artillery for the Panzer Divisions. Initially a design for a 10.5cm howitzer mounted on a Panzer III/IV chassis was considered, but with the advent of the Wespe 10.5cm self-propelled howitzer on the Panzer II hull the design was changed to mount the 15cm howitzer. The new gun was based on a lengthened Panzer IV hull with some mechanical elements from the Panzer III. The prototype was named the Hummel (Bumble-Bee). It was armed with the 15cm sFH 18/1 L/30 howitzer mounted in an open topped fighting compartment.