What is a Sturmgeschütz ? Thanks "Sturmgeschütze vor!" for help here.

Sturmartillerie (Assault Artillery) was a concept developed by the Germans in the mid 1930's. Sturmartillerie was envisioned as being armored artillery for infantry support. An existing tank chassis was modified with an armored fighting compartment and a limited traverse gun. This was the first Sturmgeschütz or Assault Gun III.

Originally fitted with 7.5cm howitzers (StuK37 L/24); the early models served well as direct (and indirect) fire support for the German infantry.  The 7.5cm howitzer had a rudimentary anti-tank capability which was adequate during the French campaign and the early stages of the invasion of Russia.  Contact with the Soviet T-34 in 1941 convinced the Germans that a heavier gun was needed. They fitted the StuG III with high-velocity 7.5cm gun (StuK40 L/43).

The first  Sturmgeschütz entered production in 1940 and they were still being produced in 1945 when Germany collapsed.