Constituted as 320th Bombardment Group (Medium) on 10 June 1942 and activated on 23 June. Trained with B-26 aircraft. Most of the group moved North Africa via England, Aug-Dec. 1942; crews flew their planes over the South Atlantic route and arrived in North Africa, Dec. 1942-1943. Began comb at with Twelfth AF in April 1943 and operated from bases in Algeria, Tunisia, Sardinia and Corsica until Nov. 1944.
During the period April-July 1943, flew missions against enemy shipping in the approaches to Tunisia, attacked installations in Sardinia, participated in the reduction of Pantelleria, and supported the invasion of Sicily. Then bombed marshalling yards, bridges, airdromes, road junctions, viaducts, harbors, fuel dumps, defense positions, and other targets in Italy. Supported forces at Salerno and knocked out targets to aid the seizure of Naples and the crossing of the Volturo River. Flew missions to Anzio and Cassino and engaged in interdictory operations in central Italy in preparation for the advance toward Rome.
Received the French Croix de Gruerre with Palm for action in preparation for and in support of Allied offensive operations in central Italy, April-June 1944. Received a DUC for a mission on 12 May 1944. when, in the face of an intense antiaircraft barrage, the group bombed enemy troop concentrations near Fondi in support of Fifth Army's advance toward Rome. From June to Nov. 1944 operations included interdictory missions in the Po Valley, support for the invasion of Southern France, and attacks on enemy communications in northern Italy.
Moved to France in Nov. 1944 and bombed bridges, rail lines, gun positions, barracks, supply points, ammunition dumps, and other targets in France and Germany until V-E Day. Received a DUC for operations on 15 March 1945 when the group bombed pillboxes, trenches, weapon pits, and roads within the Siefied Line to enable a breakthrough by Seventh Army. Moved to Germany in June 1945 and participated in the disarmament program. Returned to the US, Nov.- Dec. Inactivated on 4 Dec. 1945. Redesignated 320th Bombardment Group (Light). Allotted to the reserve. Activated on 9 July 1947. Inactivated on 27 June 1949.