United States Air Force
The U.S. War Department created the first antecedent of the U.S. Air Force, as a part of the U.S. Army, on 1 August 1907, which through a succession of changes of organization, titles, and missions advanced toward eventual independence 40 years later. In World War II, almost 68,000 U.S. airmen died helping to win the war, with only the infantry suffering more casualties. In practice, the U.S. Army Air Forces (USAAF) was virtually independent of the Army during World War II, and in virtually all ways functioned as an independent service branch, but airmen still pressed for formal independence. The National Security Act of 1947 was signed on 26 July 1947 by President Harry S Truman, which established the Department of the Air Force, but it was not until 18 September 1947, when the first secretary of the Air Force, W. Stuart Symington, was sworn into office that the Air Force was officially formed as an independent service branch.
United States Army Air Service
The seven-year history of the post-war Air Service was essentially a prolonged debate between adherents of airpower and the supporters of the traditional military services about the value of an independent Air Force, spurred by the creation of the Royal Air Force in 1918. On one side were Brig. Gen. Billy Mitchell, Brig. Gen. Benjamin Foulois, a cadre of young former Reserve officers who made up the overwhelming majority of Army pilots, and a few like-minded politicians and newspapers. Opposed were the General Staff of the Army, its senior leadership from World War I, and the Navy. The doctrinal differences were both defined and intensified by struggles for funds caused by the skimpy budgets authorized for the War Department, first by the penurious policies of the Republican administrations in the 1920s, and then by the fiscal realities of the Great Depression. In the end, the struggle for funds as much as any other factor caused the impetus for an independent Air Force.