assault gun
A military vehicle classification: a fully armored, turretless tank-like vehicle mounting a gun, used for direct fire support of infantry. This term is primarily historical, referring to World War II-era vehicles.
During World War II, the German military produced many assault guns.
自走砲 (self-propelled gun) is a broader category that includes artillery pieces on tracked chassis, often with lighter armor. 突撃砲 is a subtype with heavy frontal armor for direct assault.
Compound of 突撃 (assault, charge) and 砲 (gun, cannon). The term is a calque from German 'Sturmgeschütz', reflecting its origin in German military doctrine.