and pieces of buildings." None of the 82 bombers on the base escaped damage, and SAC declared the division non-operational. Maintenance personnel of the 7th and 11th Wings went on an 84-hour weekly work schedule and began to restore the least damaged aircraft to operational status. More heavily damaged aircraft were worked on by personnel from the San Antonio Air Materiel Area, where the depot for the B-36 was located. The planes that had been most heavily damaged were towed across the field to the Convair plant where they had been manufactured. Within a month, 51 of the base's Peacemakers had been returned to service and the division was again declared operational. By May 1953, all but two of the planes had been returned to service. In 1959, the 3958th Operational Training and Evaluation Squadron was reassigned to the division from SAC headquarters. At the same time the squadron was upgraded to a group and assigned the 3958th Combat Crew Training Squadron and the 3958th Consolidated Aircraft Maintenance Squadron. The 3958th, along with its counterpart 6592d Test Squadron of Air Research and Development Command, representatives of Air Materiel Command, Convair and other contractors formed the Convair B-58 Hustler test force, and, at the time of the 3958th's transfer, was involved in Category II testing of the B-58. This testing phase included tests of aircraft subsystems and its J79 engines. Before Category II tests were completed, seven aircraft were lost. Category II tests, led by the 6592d, were completed by the end of June 1960, and, Category III tests (operational testing) began in August. These tests were conducted primarily by the division's 43d Bombardment Wing (Carswell AFB, Ft. Worth, Texas) with the technical assistance of the remainder of test force. In anticipation of its expanded testing and crew-training mission for the Hustler, SAC had inactivated the 3958th and transferred its mission, personnel and equipment to the 43d Bomb Wing. In January 1967, the division began deploying B-52 aircraft and aircrews to Southeast Asia for combat operations, continuing until 1973. In 1975, the 19th provided air-refueling support for the evacuation of Vietnamese and Americans from South Vietnam. With the end of the Vietnam War, the division began transitioning control of most of its B-52 wings (with the exception of the 7th Bombardment Wing at Carswell AFB) into KC-135 Stratotanker air refueling and LGM-25C Titan II ICBM wings. With the retirement of the