The Sturmgeschütz III (StuG III) was a German assault gun and the most-produced German fully tracked armored fighting vehicle of World War II. Built on a modified Panzer III chassis, it replaced the turret with a fixed superstructure mounting a more powerful gun. Initially for infantry support, it was continually modified and used as a tank destroyer. Its origins lay in WWI experiences where infantry lacked effective means against fortifications. General Erich von Manstein is considered the father of the Sturmartillerie, proposing direct fire support for infantry divisions. Daimler-Benz developed the prototype with a 7.5 cm gun in a fixed casemate. Early models had a low-velocity 7.5 cm StuK 37 L/24 gun. After encountering Soviet KV-1 and T-34 tanks, it was equipped with high-velocity 7.5 cm StuK 40 L/43 and L/48 guns. Later versions featured an MG34 machine gun for anti-infantry defense, and a coaxial MG34 became standard in 1944. The StuG III was cheaper (82,500 RM for Ausf. G) and faster to build than contemporary Panzer III Ausf. M tanks (103,163 RM) due to the turret omission.