This Week in Airpower History: July 26, 1947 – President Harry S Truman signs the National Defense Act of 1947, the enabling legislation that will create a separate Air Force Published Dec. 22, 2008 By 208113 Arnold Air Force Base, Tenn. -- On July 26, 1947, while aboard the presidential C-54 aircraft, Sacred Cow, President Harry S Truman signed the National Security Act of 1947, officially establishing the United States Air Force as a separate service under the National Military Establishment (renamed in 1949 the Department of Defense). The Act set out requirements for the Air Force that "it shall be organized, trained and equipped primarily for prompt and sustained offensive and defensive air operations. The Air Force shall be responsible for the air forces necessary for the effective prosecution of war except otherwise assigned and, in accordance with integrated joint mobilization plans, for the expansion of the peacetime components of the Air Force to meet the needs of war." On the same day he signed the National Security Act, President Truman signed Executive Order 9877 assigning the primary functions and responsibilities of the armed forces. The United States Air Force was charged to organize, train and equip air forces for air operations including joint operations; to gain and maintain general air superiority; to establish local air superiority where and as required; to develop a strategic air force and conduct strategic air reconnaissance operations; to provide airlift and support for airborne operations; to furnish air support to land and naval forces including support of occupation forces; and to provide air transport for the armed forces except as provided by the Navy for its own use. Stuart Symington was sworn in as the first Secretary of the Air Force by Chief Justice Fred Vinson on Sept. 18, 1947, establishing the United States Air Force as truly an independent arm of the U.S. military. Information compiled from the National Museum of the United States Air Force website, www.nationalmuseum.af.mil.