The official lineage of the United States Air Force began on August 1, 1907, when the Army Signal Corps created the Aeronautical Division. In July 1918, the Army established the Aviation Section of the Signal Corps to improve its flying capabilities. The Army Reorganization Act of 1920 made this air service a combat arm of the Army, and in July 1926, it became the Air Corps. General Headquarters Air Force assumed command of US-Based Air Corps Tactical Units in March 1935. The Department of War created the Army Air Forces in June 1941 and made it co-equal to the Army ground forces. On September 18, 1947, the United States Air Force became a full partner with the Army and Navy, and Stuart Syminton became the first Secretary of the Air Force. General Carl A. Spaatz became the first Chief of Staff.