22 June

Operation Barbarossa was the code name for Nazi Germany’s World War II invasion of the Soviet Union, which began on this day in 1941. The operation was driven by Adolf Hitler’s ideological desire to conquer Soviet territory, even though he was still fighting the British Commonwealth in the west.

In the two years leading up to the invasion, the two countries signed political and economic pacts for strategic purposes. Nevertheless, on 18 December 1940, Hitler authorised an invasion of the Soviet Union, with a planned start date of 15 May 1941. The actual invasion began on 22 June 1941. Over the course of the operation, about four million soldiers of the Axis powers invaded the Soviet Union along a 2,900-kilometre (1,800 mi) front, the largest invasion force in the history of warfare. In addition to troops, the Germans employed some 600,000 motor vehicles and between 600,000 and 700,000 horses. It marked the beginning of the rapid escalation of the war, both geographically and in the formation of the Allied coalition.

Operationally, the Germans won resounding victories and occupied some of the most important economic areas of the Soviet Union, mainly in Ukraine, both inflicting and sustaining heavy casualties. Despite their successes, the German offensive stalled on the outskirts of Moscow and was subsequently pushed back by a Soviet counteroffensive. The Red Army repelled the Wehrmacht’s strongest blows and forced Germany into a war of attrition for which it was unprepared. The Germans would never again mount a simultaneous offensive along the entire strategic Soviet-Axis front. The failure of the operation drove Hitler to demand further operations inside the USSR of increasingly limited scope, all of which eventually failed.

The failure of Operation Barbarossa was a turning point in the fortunes of the Third Reich. Most importantly, the operation opened up the Eastern Front, to which more forces were committed than in any other theatre of war. The Eastern Front became the site of some of the largest battles, most horrific atrocities, and highest casualties for Soviets and Germans alike, all of which influenced the course of both World War II and the subsequent history of the 20th century. The German forces captured millions of Soviet prisoners who were not granted protections stipulated in the Geneva Conventions. Most of them never returned alive; Germany deliberately starved the prisoners to death as part of a “Hunger Plan” that aimed to reduce the population of Eastern Europe and then re-populate it with ethnic Germans. Over a million Soviet Jews were murdered by Einsatzgruppen death squads and gassing as part of the Holocaust.