The group was first activated at Salt Lake City Army Air Base, Utah in September 1942, with the 502d, 503d, 504th and 505th Bombardment Squadrons assigned The following month, it moved to Smoky Hill Army Air Field, Kansas, where it began operating as an Operational Training Unit. The Army Air Forces OTU program involved the use of an oversized parent unit to provide cadres to "satellite groups". Initially, the goup's 503d and 504th Squadrons were equipped with Boeing B-17 Flying Fortresses, but by the end of the year, the group was entirely equipped with the Consolidated B-24 Liberator. With the Liberator, the mission changed to acting as a Replacement Training Unit. Like the OTUs, RTUs were oversized units, but their mission was to train individual aircrews, rather than units. However, the AAF was finding that standard military units, based on relatively inflexible tables of organization were not well adapted to the training mission. In response, the group's squadrons lost their aircraft and the training mission was concentrated in group headquarters in October 1943. Ultimately, The AAF adopted a functional system in which each base was organized into a separate numbered unit, which would be manned and organized specifically for the mission. The 346th Group and its squadrons were inactivated on 1 April 1944, along with support organizations at Dyersburg Army Air Base, Tennessee, and replaced by the 223d AAF Base Unit
Very heavy bomber operations
The group was reactivated at Dalhart Army Air Field, Texas in August 1944 as a very heavy bomber unit. However, the group's component squadrons were not activated with it. Instead, the 461st, 462d and 463d Bombardment Squadrons, which had been components of the 331st Bombardment Group were assigned to the 346th. The group trained with Boeing B-29 Superfortress at Dalhart and at Pratt Army Air Field, Kansas until late June 1945, when it departed the United States for the Pacific Theater. The group did not arrive at its combat station, Kadena Airfield, on Okinawa until 7 August 1945 and the war ended before it could participate in combat operations, although members of the unit intended to be lead crews flew missions with other units from Saipan, Tinian and Guam. After the war the group participated in several show-of-force missions over Japan and for a time ferried Allied prisoners of war from Okinawa to the Philippine Islands. It served with the occupation forces until it was inactivated in June 1946.
Lineage
Constituted as the 346th Bombardment Group on 3 September 1942
Redesignated 346th Bombardment Group, Very Heavy on 4 August 1944