received 53 of the 65 produced) were transferred in 1949 to the 97th Bomb Wing at Biggs Air Force Base, El Paso, Texas, when the group converted to B-50D Superfortresses. The B-50D was the last derivative of the B-29 family and designed specifically for the atomic bombing mission. It was one of the last piston-engined bombers built, having a top speed just short of 400 mph (644 km/h), faster than many World War II-era piston-engined fighters still in service at the time. During the Korean War, the 509th remained in the United States as President Harry S. Truman wasn't willing to risk extensive use of the USAF strategic bomber force, which was being used as a deterrent for possible Soviet aggression in Europe. Its squadrons were removed on 1 February 1951, and assigned directly to the wing, effectively ending its operations. The 509th was inactivated on 16 June 1952 as part of a SAC (and later Air Force-wide) phase-out of groups with the adoption of the Tri-Deputate organization. The 509th Bomb Wing moved its people and equipment to Pease AFB in August 1958. There, the wing continued to function as an integral part of SAC. By 1965, its B-47s for were scheduled for retirement. Unfortunately, this retirement also included the 509th. Fate intervened, however, as SAC decided to keep the 509th alive and equipped it with B-52s and KC-135s. Thus, the wing received its first B-52 and KC-135 in March 1966. The wing's association with the B-52 included two major deployments to Andersen AFB, Guam, as part of the now famous Vietnam War Arc Light missions. In April 1968 and again in April 1969, the wing began six-month ventures in the Western Pacific. During the last deployment, SAC informed the 509th that the wing would swap its B-52s for FB-111As. Accordingly, the wing began receiving the formidable fighter-bomber in December 1970. Over the next two decades, little changed for the 509th BW as it became SAC's fighter-bomber experts. However, a decision by the Department of Defense in 1988 to close Pease created major changes for the famous 509th. Headquarters SAC decreed that the 509th would not inactivate but transfer to Whiteman AFB to become the first B-2 Stealth bomber unit. As such, the wing moved to Whiteman on 30 September 1990, without people and equipment. Modern era The 509th Bomb Group was redesignated as the 509th Operations Group and activated