The 405th Fighter Squadron was activated at Richmond Army Air Base, Virginia in the summer of 1943 as one of the three original squadrons of the 371st Fighter Group. The squadron trained in the northeastern United States with Republic P-47 Thunderbolts under First Air Force before moving overseas in the spring of 1944.
Upon arriving in England, the squadron became an element of Ninth Air Force at Bisterne Close, England. The squadron's first combat operation was a fighter sweep over Occupied France. Prior to Operation Overlord, the invasion of Normandy, the 405th flew fighter sweeps, dive bombing and escort missions.
On D-Day the 405th patrolled the beachhead. attacking railroads, trains, vehicles. gun emplacements and other targets. Soon after the invasion, the squadron moved to France and participated in the air interdiction that preceded the Allied breakout at St Lo in late July and supported the following drive across northern France. It continued to operate in northeastern France and southwestern Germany through the winter of 1945, attacking storage dumps, marshalling yard, factories, bridges, roads, and vehicles. In December 1944 it provided close air support for ground forces engaged in the Battle of the Bulge.
The squadron was awarded a Distinguished Unit Citation for its attacks between 15 March and 21 March 1945 that contributed to the defeat of Axis forces in southern Germany. It continued combat operations until the Surrender of Germany in May. The squadron remained with the occupation forces in Germany and Austria until October 1945 when it returned to the United States and was inactivated.
The wartime 405th Fighter Squadron was re-activated and re-designated as the 190th Fighter Squadron, and was allotted to the Idaho Air National Guard, on 24 May 1946. It was organized at Gowen Field, south of Boise. It was extended federal recognition on 13 October 1946. The 190th Fighter Squadron was bestowed with the history, honors, and colors of the 405th Fighter Squadron.