Constituted as 504th Bombardment Group (Very Heavy) on 18 Feb 1944. Activated on 11 Mar 1944. Equipped first with B-17's; later trained for combat with B-29's. Moved to the Asiatic-Pacific Theater late in 1944 for service with Twentieth AF. Began combat operations from Tinian in Jan 1945 with attacks on Japanese airfields and other installations on Maug and Iwo Jima and in the Truk Islands. Flew its first mission against the Japanese home islands early in Feb 1945 when the group bombed the industrial area of Kobe. Continued to attack strategic targets in Japan, operating in daylight and at high altitude to bomb such objectives as aircraft factories, chemical plants, harbors, and arsenals. Received a DUC for striking the industrial center at Yokohama late in May 1945. Began incendiary raids in Mar 1945, flying at night and at low altitude to strike area targets in Japan. Started mining operations against enemy shipping late in Mar, receiving a DUC for mining Korean shipping lanes, the Shimonoseki Strait, and harbors of the Inland Sea, Jul-Aug 1945. In Apr and May 1945 the group hit airfields from which the Japanese launched kamikaze planes against the invasion force during the assault on Okinawa. After the war it dropped food and supplies to Allied prisoners, participated in show-of-force missions, and flew over Japan to evaluate damage inflicted by bombardment operations. Moved to the Philippines in Mar 1946. Inactivated on Luzon on 15 Jun 1946.
Squadrons. 393d: 1944. 398th: 1944-1946. 421st: 1944-1946. 507th: 1944. 680th: 1944-1946.
Stations. Dalhart AAFld, Tex, 11 Mar 1944; Fairmont AAFld, Neb, 12 Mar-5 Nov 1944; North Field, Tinian, 23 Dec 1944; Clark Field, Luzon, 6 Mar-15 Jun 1946.
Commanders. Capt Basil D Murray, Mar 1944; Col James T Connally, 6 Apr 1944; Col Glen W Martin, 6 Feb 1945; Col Charles B Root, 18 Sep 1945; Col John P Kenny, 2 Apr-15 Jun 1946.
Campaigns. Air Offensive, Japan Eastern Mandates; Western Pacific.
Decorations. Distinguished Unit Citations: Yokohama, Japan, 28 May 1945; Japan and Korea, 27 Jul-14 Aug 1945.
Data from Air Force Combat Units of World War II By Maurer, Maurer, Published 1986