In the fall of 1950, the Air National Guard implemented the wing base organization ("Hobson Plan") used by the regular air force. The 113th Fighter Wing was formed as the headquarters for the 113th Fighter Group and its supporting units. With the surprise invasion of South Korea on 25 June 1950, and the regular military's lack of readiness, most of the Air National Guard was federalized and the 113th Wing was called to active duty on 1 February 1951. The wing was assigned to Air Defense Command (ADC) and was redesignated as the 113th Fighter-Interceptor Wing. Its 113th Fighter-Interceptor Group was composed of the District of Columbia Air National Guard 121st and Delaware Air National Guard 142d Fighter-Interceptor Squadrons, both equipped with Republic F-84C Thunderjets, along with the Pennsylvania Air National Guard North American F-51D Mustang equipped 148th Fighter Squadron From Spaatz Field, Reading.