Assault guns (Sturmgeschütz in German) were armored fighting vehicles similar to tanks, with the chassis and tracks of a panzer but without the rotating turret, which allowed the mounting of a larger gun. They were usually used to support infantry assaults, but they also proved effective as tank destroyers, especially late in the war when German tank inventory diminished. Among the most famous variants are the Sturmtiger and Brummbär ("Grouch"). Hans Wijers has assembled hundreds of photos—most of them never seen anywhere before—of these vehicles at war on the Eastern Front of World War II.