This paper deals with the contributions of the United States Air Force to the eventual victory of the Allies in Europe during World War II. The Allied powers had no idea how important a strong air force would be against the Axis powers during World War II. The fact that Hitler moved east in 1941 and had planned to do so since 1940, had important implications for the British war effort. Though still powerless to prevent German initiatives from being successful in Greece and Crete, the British government was given a long period during which to prepare adequate defenses in the mainland against the expected day when Hitler would turn west again. Although it was true that Germany would have the luxury after a defeat of the Soviet Union to concentrate solely on defeating Britain, and Hitler gave specific directives for such a contingency, it was also true that Britain was much stronger than in 1940. In fact very little active planning was carried out in Germany for the renewed fight against Britain, and the crucial diversion of resources in the economy for the air effort was not carried out. Even victory against Russia therefore would not necessarily have led to the destruction of British resistance for a considerable time.Britain now had another advantage; close ties with the United States in 1940 had been turned into firm commitments to provide assistance in 1941. In September 1940 the Army-Navy-British Purchasing Commission Joint Committee was set up to discuss and arrange sales of aircraft to Britain and to try to achieve some standardization of production. The United States undertook to expand its own aircraft industry enormously and to provide the bulk of the new aircraft to the British, an offer whose generosity was tempered by the fact; "…argued by General Marshall, that if Britain was defeated the aircraft would be needed anyway to defend the Western Hemisphere. Throughout 1941 the aid continued to expand." (Overy 60)Allied...