73d Air Division The 73d Air Division ( 73d AD ) is an inactive United States Air Force unit . Its last assignment was with Air Defense Command , based at Tyndall Air Force Base , Florida . It was inactivated on 1 April 1966 . History . World War II . The 73d Bombardment Wing was activated as part of Second Air Force on 17 February 1943 . Its original mission was a control organization for Replacement Training Units ( RTU ) , with command and control over B - 17 / B - 24 training units based in the midwest . It was inactivated on 15 October 1943 with the phasedown of heavy bomber training . The wing was reactivated and redesignated as the 73d Bombardment Wing ( Very Heavy ) on 20 November 1943 at Smoky Hill Army Airfield , Kansas . The new B - 29 Superfortress wing was assigned four newly organized groups , ( 497th , 498th , 499th and 500th Bombardment Groups ) which were training in New Mexico and Arizona on B - 17 and B - 24s , due to a lack of B - 29 aircraft . In April 1944 , the groups were brought to several airfields in Kansas ( Great Bend AAF , Smokey Hill AAF and Walker AAF ) where they were equipped with new B - 29s manufactured by Boeing at their Wichita , Kansas plant . By August the wing ' s groups completed their training and their aircraft were readied for deployment . Originally assigned to Twentieth Air Force ' s XX Bomber Command in India , the wing was instead assigned to the new XXI Bomber Command in the Pacific Theater . The 73d Wing deployed to newly - constructed airfields on Saipan in the Northern Mariana Islands . The 73d Bomb Wing was the first B - 29 wing to be assigned to the Marianas , and the first B - 29 of the 497th Bomb Group arrived at Isely Field , Saipan on 12 October 1944 . The 498th arrived shortly after , with the 499th and 500th Bomb Groups arriving in early November . By November 22 , over 100 B - 29s were on Saipan . The XXI Bomber Command was assigned the task of destroying the aircraft industry of Japan in a series of high - altitude , daylight precision attacks In late October and early November 1944 , a series of tactical raids were carried out as training exercises for the crews . From Saipan , the groups of the 73d Bomb Wing flew several bombing missions against Truk to gain combat experience . Aware that there was now a new threat , Japanese aircraft based on Iwo Jima staged a low - level raid on Isely Field on November 2 , damaging several B - 29s on the ground . Retaliatory strikes were ordered on Iwo Jima on November 5 and 11 . In November 1944 , the groups of the 73rd began bombing Japan , with only moderate success . Poor weather , the lack of precision radar bombing equipment , and tremendous winds encountered at high altitudes over Japan made accuracy difficult . The initial raids against Japan had taken place at high altitudes in order to stay above anti - aircraft fire and the effective altitude of defending fighters . Tactics were changed and high - altitude , daylight attacks be phased out and replaced by low - altitude , high - intensity incendiary raids at nighttime . The aircraft would attack individually , which meant that no assembly over the base at the start of the mission or along the way would be needed . Consequently , it turned to devastating low altitude incendiary attacks . The Division continued attacking urban areas until the end of the war in August 1945 , its subordinate units conducted raids against strategic objectives , bombing aircraft factories , chemical plants , oil refineries , and other targets in Japan . The wing flew its last combat missions on 14 August when hostilities ended . Afterwards , the wing ' s B 29s carried relief supplies to Allied prisoner of war camps in Japan and Manchuria . Being the first deployed wing of XXI Bomber Command , the 73d and its subordinate units demobilized rapidly after V - J Day , and the wing ' s four bomb groups were all returned to the United States , with their B - 29s either being flown to Clark Air Base for scrapping , or were flown to storage facilities in Texas or Arizona . The 73d Bomb Wing was reassigned to the United States in December 1945 , being assigned first to Continental Air Force ' s Fourth Air Force , then to the new Strategic Air Command on 21 March 1946 . However demobilization was in full swing and few SAC units were actually equipped and manned . The 73d Bomb Wing was inactivated on 31 March and the unit was allocated on paper to the Air Force Reserve . Air Force Reserve . In 1947 , the 73d Bomb Wing was reactivated with the 338th and 351st Bomb Groups being assigned to it , both reserve B - 29 Superfortress organizations . A third group , the 381st was added in 1948 . However SAC was having enough difficulties keeping its front - line active duty B - 29 bomb units in the air to maintain even minimal pilot proficiency in the late 1940s . The wing and its bomb groups were all inactivated in 1949 . Air Defense Command . The organization was reactivated as part of Air Defense Command ( ADC ) in 1957 as the 73d Air Division . As part of ADC , it evaluated , upgraded , and determined the proficiency of the Air Defense Command fighter - interceptor and missile squadrons , 1 July 1957 – 1 April 1966 . The division developed and tested Air Defense Command tactics , equipment , aircraft , guided missiles , and related equipment and armaments . It also maintained active contact with Army , Navy , and other Air Force commands to assure coordinated military effort in the use of rocket and missile ranges , defense plans , air sea land rescue , and airspace and airways directly concerned with the operations of the Air Defense Command Weapons Center . With the diminishing need for an active - duty air defense mission in the United States , the 73d Air Division was inactivated on 1 April 1966 .