After the outbreak of World War II it moved to Halifax to provide anti-ship capability, but was redesignated as a fighter squadron while in transit.

3 (Operations) Squadron, which flew forestry patrols over Ontario and Quebec to support civil government between 1925 and 1927.

Shearer, it flew forestry patrols over Ontario and Quebec to support civil government, in addition to "operating a test and development centre for new aircraft and photographic equipment."

3 (Advanced Training) Squadron, but due to a lack of aircraft, funding, and personnel it only existed on paper.

After the delivery of four Wapiti Mark IIAs on 1 June 1937, the squadron was reorganized with only bomber aircraft and the Fighter Flight expanded into No.

Though the Wapiti proved unpopular with its pilots due to its poor performance, the Canadian government would not spend more money for superior aircraft.

[9] During 1938, the squadron received four more Wapitis to form an additional flight, though only four of its aircraft were equipped with wireless, logging 1,000 training hours.

[10] In addition to practicing bombing with camera obscura during the year, the squadron flew simulated low-level bombing and gas attacks as part of the opposing force during Canadian Army exercises at Camp Borden in late August and early September.

[15] Training continued, with squadron aircraft launching mock strafing and gas attacks against militia during their annual summer camp.

[14] Shortly before World War II began, on 26 August, the squadron was alerted for hostilities, immediately departing with seven obsolete Wapitis for the civil aerodrome at Halifax, Nova Scotia, where it joined Eastern Air Command on 1 September with half of its aircraft.

It received three new Wapitis with crews on 30 August from Trenton while stopping at Rockcliffe, bringing total strength to two flights with five aircraft each.

[17] Flying in short spurts, the aircraft took the direct route to Halifax, overflying American territory.

The three remaining aircraft were forced down in Millinocket, Maine by engine trouble, risking internment if war was declared.

At Halifax, the squadron formed the Air Striking Force of Eastern Air Command, intended to launch attacks, either independently or in cooperation with the Royal Canadian Navy, against any German surface forces[18] operating between Port Mouton and Cape Canso.

3 (Bomber Reconnaissance) Squadron planned to be equipped with Consolidated Canso flying boats was ordered organized on 1 June 1943 due to a perceived need for additional anti-submarine units, but the order was swiftly cancelled after a reduction in the U-boat threat.