The 575th Air Defense Group is a disbanded United States Air Force organization. Its last assignment was with the 4708th Air Defense Wing at Selfridge Air Force Base, Michigan, where it was inactivated in 1955. The group was originally activated as a support unit for the 4th Fighter Group after the 4th returned to the US at the end of World War II and performed that mission until it was inactivated in 1947. The group was activated once again in 1952 to replace the support elements of the inactivating 56th Fighter-Interceptor Wing. A year later ADC established it as an operational headquarters for fighter-interceptor squadrons as well. It was replaced in 1955 when ADC transferred its mission, equipment, and personnel to the 1st Fighter Group in a project that replaced air defense groups com