In August 1938, a complete re-organization of the Army Air Service resulted in the creation of the , which replaced all of the former Air Battalions and Air Regiments. Each Air Combat Group was a single-purpose unit consisting typically of three Squadrons, divided into three of three aircraft each. Together with reserve aircraft and the headquarters flight, an Air Combat Group typically had 45 aircraft (fighter) or up to 30 aircraft (bomber or reconnaissance). Two or more Air Combat Groups formed an , which, together with base and support units and a number of Independent Squadrons, formed an .