In 1953, the Strategic Air Command brought the jet age to Davis-Monthan Air Force Base in Tucson with dozens of Boeing B-47 Stratojet bombers as part of U.S. efforts to counter the Soviet threat of invasion. The planes could carry conventional and nuclear payloads 3,000 miles before refueling. Nearly 1,100 personnel at D-M kept the planes in the air. The Air Force began retiring the B-47 in the mid-1960s.