The 18th Panzer Division first saw action during the German invasion of the Soviet Union, Operation Barbarossa, on 22 June 1941. The 18th Panzer Division fought as part of XLVII Panzer Corps, and over the next six months was involved in seizing Smolensk, Bryansk and the assault on Tula. The division suffered heavy losses in the first month of the war, losing half its tanks and a third of its manpower in June and July.