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.

Prior to Operation Overlord, the invasion of Normandy, the 405th flew fighter sweeps, dive bombing and escort missions.

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.

[4] The squadron was awarded a Distinguished Unit Citation for its attacks between 15 and 21 March 1945 that contributed to the defeat of Axis forces in southern Germany.

[4] 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 volunteers – 23 officers and 44 enlisted men – met one night each week in a small building on Fort Street in downtown Boise.

Personnel were sent to Moody AFB, Georgia to replace active-duty airmen sent to Korea, and the squadron became a F-51D Fighter-Bomber training unit.

It was re-equipped by Tactical Air Command with the RF-4C Phantom II Mach 2 high speed reconnaissance aircraft.

F-4 Phantom jets would eventually spend 20 years on Gowen Field, longer than any other aircraft in the history of Idaho's Air National Guard.

The unarmed RF-4C carried high resolution cameras and electronic sensors, which soon proved their worth to thousands of people in Idaho.

Idaho airmen and Phantom jets went to Canada and Norway to provide critical tactical reconnaissance capabilities to U.S. and NATO forces.

Idaho's airmen served longer in Southwest Asia than any other flying unit in the Air National Guard.

Idaho's A-10s led combat search and rescue and close air support missions in the initial weeks and months of the war.

As part of the invasion of Iraq and supporting the British portion of that operation called Operation Telic, on 28 March 2003 two 190th A-10 Thunderbolt II aircraft, flown by an unidentified Major and Lieutenant Colonel Gus Kohntopp, flew a mission to destroy artillery and rocket launchers from Iraq's 6th Armor Division, dug in 25 miles (40 km) north of Basra.

During the mission, the two A-10 aircraft mistakenly attacked a patrol of four armored vehicles from D Squadron of the British Blues and Royals of the Household Cavalry that were supporting the 16 Air Assault Brigade in Operation Telic.

As a result of the attack by the 190th A-10 aircraft, British Lance-Corporal of Horse (L/CoH) Matty Hull was killed, and five of his colleagues were injured, four seriously.

[8] On 16 March 2007, the inquest coroner, Andrew Walker, returned a narrative verdict, stating that the killing of L/CoH Hull was "unlawful".