The Second World War

The distinction between the Auxiliary Active Air Force and the Permanent Active Air Force disappeared when the Auxiliary was mobilized on 3 September 1939. At that time, the Auxiliary consisted of 12 squadrons and constituted one-third of the RCAF strength.

Of the 12 Auxiliary squadrons, only five were initially fully mobilized. The remaining seven were disbanded because of lack of personnel; however, five were later reformed and served as part of the Home War Establishment.

Two of the three initial RCAF squadrons that deployed to England in 1940 were Auxiliary units - Nos. 110 and 112. Both anticipated serving in France; however, with the fall of that nation, they were relegated to training. The Squadrons were renumbered on 1 March 1941, becoming Nos. 400 and 402 Squadrons and reaching operational status in November and March 1941 respectively. Squadron Leader F.M. Gobeil, Commanding Officer of 242 (Canadian) Squadron and an Auxiliary Active Air Force pilot, scored the RCAF's first aerial victory by shooting down a German Bf 110 over Belgium on 25 May 1940.

On the home front, No. 119 Squadron served in an anti-submarine role in the Gulf of St. Lawrence while No. 120 performed a similar role on the West Coast. Both were disbanded in 1944. No. 118 Squadron served in the Aleutians as a fighter squadron until 1943 when it was redesignated No. 438 and deployed to England.