Operation Barbarossa was the code name for the German invasion of the Soviet Union, which was launched on June 22, 1941. German chancellor Adolf Hitler was convinced that if his troops could control the massive Soviet landmass, with its enormous supplies of natural resources, Great Britain would be forced to negotiate a peace. The Nazi attack on the Soviets turned into the greatest battle of World War II.
Hitler wanted to invade Russia for both ideological and tactical reasons. The Soviet Union contained too many Jews and Bolsheviks according to Hitler's philosophy of Aryan supremacy. It also contained valuable oil supplies necessary to carry war to Eastern Europe and recapture former German lands. Hitler planned to defeat the Soviets and annex the Baltic states, the Crimea, and portions of Poland.
Nazi Germany and the Soviet Union had signed a nonaggression pact in August 1939, but Hitler apparently began planning an attack against the Soviet Union after the fall of France in June 1940. The ideologies of fascism and communism were bitterly opposed, and any truce could only have been temporary. An invasion of Britain across the English Channel was virtually impossible for the Germans because of their limited naval power. A drive to the east and a quick victory over the Soviets would have put Germany in control of the whole of continental Europe.
About 3 million German and allied Romanian, Bulgarian, and Finnish troops were used in the June 22, 1941 launching of Operation Barbarossa along thousands of miles of Soviet territory. The Soviets were caught completely by surprise, and in the early weeks of the invasion, hundreds of thousands of Russian Red Army troops were killed or captured. The bulk of the Soviet Air Force was destroyed on the ground by the Luftwaffe (German Air Force), and by July, it looked like the Nazis would take Moscow and Leningrad (now St. Petersburg).
Hitler, however, argued with his generals over whether Moscow should be the primary objective of the invasion, and German troops were diverted toward Leningrad and the Crimean peninsula. By late summer, the Soviets had received reinforcements, and heavy rains during October made the Russian roads impassable for the mechanized Nazi armies. In December, the Germans reached a point only a few miles from Moscow, but by that time, the bitterly cold Russian winter had arrived. German tanks and weapons failed to function in the subzero temperatures, and the army was forced to retreat.
The German campaign that had began as a spirited assault had now ground to a halt. Operation Barbarossa had failed to achieve a rapid victory, and Germany was bogged down in a costly, two-front war that would eventually end with a victory by the Allies in 1945.