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 Air Force
Although provision is made in Title 10 of the United States Code for the Secretary of the Air Force to appoint warrant officers, the Air Force does not currently use warrant officer grades, and is the only one of the U.S. Armed Services not to do so. The Air Force inherited warrant officer ranks from the Army at its inception in 1947. The Air Force stopped appointing warrant officers in 1959, the same year the first promotions were made to the new top enlisted grade, Chief Master Sergeant. Most of the existing Air Force warrant officers entered the commissioned officer ranks during the 1960s, but small numbers continued to exist in the warrant officer grades for the next 21 years.