The Sturmgeschütz III (StuG III) assault gun was Germany's second most-produced armoured fighting vehicle during World War II after the Sd.Kfz. 251 half-track.
It was built on the chassis of the proven Panzer III tank, replacing the turret with an armored, fixed superstructure mounting a more powerful gun. Initially intended as a mobile assault gun for direct-fire support for infantry, the StuG III was continually modified, and much like the later Jagdpanzer, was employed as a tank destroyer.
The Sturmgeschütz originated from German experiences in World War I, when it was discovered that, during the offensives on the Western Front, the infantry lacked the means to effectively engage fortifications. The artillery of the time was heavy and not mobile enough to keep up with the advancing infantry to destroy bunkers, pillboxes, and other minor fortifications with direct fire. Although the problem was well known in the German army, it was General Erich von Manstein who is considered the father of the Sturmartillerie (assault artillery).