Operation Barbarossa

Operation Barbarossa was the invasion of the Soviet Union by Nazi Germany and several of its European Axis allies starting on Sunday, 22 June 1941, during World War II. More than 3.8 million Axis troops invaded the western Soviet Union along a 2,900-kilometer (1,800 mi) front, with the main goal of capturing territory up to a line between Arkhangelsk and Astrakhan, known as the A–A line. The attack became the largest and costliest military offensive in human history, with around 10 million combatants taking part in the opening phase and over 8 million casualties by the end of the operation on 5 December 1941. It marked a major escalation of World War II, opened the Eastern Front—the largest and deadliest land war in history—and brought the Soviet Union into the Allied powers.

The operation, code-named after the Holy Roman Emperor Frederick Barbarossa ("red beard"), put into action Nazi Germany's ideological goals of eradicating communism and conquering the western Soviet Union to repopulate it with Germans under Generalplan Ost, which planned for the removal of the native Slavic peoples by mass deportation to Siberia, Germanisation, enslavement, and genocide. The material targets of the invasion were the agricultural and mineral resources of territories such as Ukraine and Byelorussia and oil fields in the Caucasus. The Axis eventually captured five million Soviet Red Army troops on the Eastern Front and deliberately starved to death or otherwise killed 3.3 million prisoners of war, as well as millions of civilians. Mass shootings and gassing operations, carried out by German paramilitary death squads and collaborators, murdered over a million Soviet Jews as part of the Holocaust.

In the two years leading up to the invasion, Nazi Germany and the Soviet Union signed political and economic pacts for strategic purposes. Following the Soviet occupation of Bessarabia and Northern Bukovina in July 1940, the German High Command began planning an invasion of the country, which was approved by Adolf Hitler in December. In early 1941, Soviet leader Joseph Stalin, despite receiving intelligence about an imminent attack, did not order a mobilization of the Red Army, fearing that it might provoke Germany.