Launched on 22 June 1941 and named after the 12th-century Holy Roman emperor Frederick Barbarossa, the German invasion of the Soviet Union represented a decisive breaking of the 1939 Nazi-Soviet pact. The Axis attacking forces of more than 3 million men split into three groups, aimed at Leningrad, Kiev and Moscow.
The Soviets were caught by surprise and suffered appallingly in the early exchanges, losing millions of men, as well as cities such as Kiev, Smolensk and Vyazma. However, the German losses were also high and, a combination of improving Soviet defences and the Russian winter halted the Wehrmacht outside the gates of Moscow in December. Meanwhile, Adolf Hitler had opted not to fight for Leningrad, instead subjecting the city to a lengthy siege.
Although the Soviet Union survived the initial onslaught, the German forces launched renewed attacks in 1942 that made further inroads into Soviet territory. It took the battle of Stalingrad of 1942–43 to decisively turn the tide and begin the long process of reversing German gains.
