Its last assignment was with the 407th Strategic Fighter Wing at Great Falls Air Force Base, Montana, where it was inactivated on 1 July 1957.

It returned to the United States the following month and was redesignated the 517th Fighter-Bomber Squadron, while continuing to train for combat with the same mission.

The first combat sorties by elements of the 407th Group were flown on 4 August 1943, in an attack against antiaircraft artillery batteries in the main Japanese camp.

[4] Initially the squadron flew a mix of the A-36 Apache and early model P-51 versions of the Mustang fighter, but by the end of the year had become a Republic P-47 Thunderbolt training unit at Galveston Army Air Field, Texas.

[1] However, the Army Air Forces were finding that standard military units like the 517th, which were manned based on relatively inflexible tables of organization were not proving well adapted to performing the training mission.