Constituted as 40th Bombardment Group (Medium) on 22 Nov 1940. Activated in Puerto Rico on 1 Apr 1941. Redesignated 40th Bombardment Group (Heavy) in May 1942. Trained and patrolled the Caribbean area, using B-17 and B-26 aircraft. Operated first from Puerto Rico and later from the Panama Canal Zone.
Moved to the US in Jun 1943. Redesignated 40th Bombardment Group (Very Heavy) in Nov 1943. After training with B-29's, moved to India, via Africa, Mar-Jun 1944. Assigned to Twentieth AF in Jun 1944. Transported supplies over the Hump to staging bases in China before entering combat with a strike on railroad shops at Bangkok, Thailand, on 5 Jun 1944. On 15 Jun participated in the first AAF attack on Japan since the Doolittle raid in 1942. Operating from bases in India, and at times staging through fields in China, the group struck such targets as transportation centers, naval installations, iron works, and aircraft plants in Burma, Thailand, China, Japan, Indonesia, and Formosa, receiving a DUC for bombing iron and steel works at Yawata, Japan, on 20 Aug 1944. From a staging field in Ceylon, it mined waters near the port of Palembang, Sumatra, in Aug 1944.
Moved to Tinian, Feb-Apr 1945, for further operations against Japan. Made daylight attacks from high altitude on strategic targets, participated in incendiary raids on urban areas, and dropped mines in Japanese shipping lanes. Received a DUC for attacking naval aircraft factories at Kure, oil storage facilities at Oshima, and the industrial area of Nagoya, in May 1945. Raided light metal industries in Osaka in Jul 1945, being awarded another DUC for this mission. After V-J Day, dropped food and supplies to Allied prisoners in Japan, Korea, and Formosa, and took part in show-of-force missions. Returned to the US in Nov 1945. Assigned to Strategic Air Command on 21 Mar 1946. Inactivated on 1 Oct 1946.
Squadrons. 25th: 1943-1946. 29th: 1941-1943. 44th: 1941-1946. 45th: 1941-1946. 74th: 1942-1943. 343d: 1945-1946. 395th: 1942-1946.
Stations. Borinquen Field, PR, 1 Apr 1941; Howard Field, CZ, 16 Jun 1942; Albrook Field, CZ, 16 Sep 1942; Howard Field, CZ, 3-15 Jun 1943; Pratt AAFld, Kan, 1 Jul 1943-12 Mar 1944; Chakulia, India, 2 Apr 1944-25 Feb 1945; West Field, Tinian, 4 Apr-Nov 1945; March Field, Calif, 27 Nov 1945; Davis-Monthan Field, Ariz, 8 May-1 Oct 1946.
Commanders. Lt Col William B Sousa, 1 Apr 1941; Maj George W McGregor, 29 Apr 1941; Col Ivan M Palmer, 26 Nov 1941; Col Vernon C Smith, 19 Jan 1943; Col Henry K Mooney, 16 May 1943; Col Lewis R Parker, 1 Jul 1943; Lt Col Louis E Coira, 24 Feb 1944; Col Leonard F Harman, 10 Apr 1944; Col William H Blanchard, 4 Aug 1944; Col Henry R Sullivan, 16 Feb 1945; Col William K Skaer, 27 Feb 1945; Lt Col Oscar R Schaaf, 21 Mar 1946; Col Alva L Harvey, 4 May 1946; Lt Col Oscar R Schaaf, 21 Aug 1946; 1st Lt William F Seith, 21 Sep-1 Oct 1946.
Campaigns. Antisubmarine, American Theater; India-Burma; Air Offensive, Japan; China Defensive; Western Pacific; Central Burma.
Decorations. Distinguished Unit Citations: Yawata, Japan, 20 Aug 1944; Japan, 5-14 May 1945; Japan, 24 Jul 1945.
Insigne. Shield: Azure, on a bomb burst proper fimbriated argent four drop bombs in cross or. (Approved 28 Mar 1942. This insigne was replaced 6 Jan 1954.)
Data from Air Force Combat Units of World War II By Maurer, Maurer, Published 1986