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Invasion of the Soviet Union

On 22 June 1941, contravening the Molotov–Ribbentrop Pact, about 3.8 million Axis troops attacked the Soviet Union. In addition to Hitler's stated purpose of acquiring Lebensraum, this large-scale offensive—codenamed Operation Barbarossa —was intended to destroy the Soviet Union and seize its natural resources for subsequent aggression against the Western powers. The reaction among Germans was one of surprise and trepidation as many were concerned about how much longer the war would continue or suspected that Germany could not win a war fought on two fronts.

The invasion conquered a huge area, including the Baltic states, Belarus, and west Ukraine. After the successful Battle of Smolensk in September 1941, Hitler ordered Army Group Centre to halt its advance to Moscow and temporarily divert its Panzer groups to aid in the encirclement of Leningrad and Kyiv. This pause provided the Red Army with an opportunity to mobilise fresh reserves. The Moscow offensive, which resumed in October 1941, ended disastrously in December. On 7 December 1941, Japan attacked Pearl Harbor, Hawaii. Four days later, Germany declared war on the United States.

Food was in short supply in the conquered areas of the Soviet Union and Poland, as the retreating armies had burned the crops in some areas, and much of the remainder was sent back to the Reich. In Germany, rations were cut in 1942. In his role as Plenipotentiary of the Four Year Plan, Hermann Göring demanded increased shipments of grain from France and fish from Norway. The 1942 harvest was good, and food supplies remained adequate in Western Europe.

Germany and Europe as a whole were almost totally dependent on foreign oil imports. In an attempt to resolve the shortage, in June 1942 Germany launched Fall Blau ("Case Blue"), an offensive against the Caucasian oilfields. The Red Army launched a counter-offensive on 19 November and encircled the Axis forces, who were trapped in Stalingrad on 23 November. Göring assured Hitler that the 6th Army could be supplied by air, but this turned out to be infeasible. Hitler's refusal to allow a retreat led to the deaths of 200,000 German and Romanian soldiers; of the 91,000 men who surrendered in the city on 31 January 1943, only 6,000 survivors returned to Germany after the war.