June 22, 1941 -- Germany attacks the Soviet Union

Operation Barbarossa (German: Unternehmen Barbarossa) began on 22 June 1941.

Over 4.5 million troops of the Axis powers invaded the USSR along a 2,900 km (1,800 mi) front.

Operation Barbarossa was the largest military operation in human history in both manpower and casualties. Its ultimate failure was a turning point in the Third Reich's fortunes.

(Right, a Soviet poster showing a Soviet tank crushing German leaders)