The main role of the Royal Canadian Air Force at home was it's contribution to the Empire Air Training Scheme in Canada, providing the nations air defence, maritime patrols in support of the Atlantic convoys, and anti U boat operations.

During the period 1939 – 45 a total of 131,553 aircrew were trained through the E.A.T.S schools, of which 80% were Canadian nationals. At it's peak in 1943, more than 3000 students were leaving the training schools EACH MONTH.

In 1941, with the entry of the Japanese into the hostilities, Canada, together with the United States, took measures to strengthen it's Pacific coastline. As a result 34 new flying squadrons were formed operating new aircraft such as Liberators, Hudsons and Catalinas.

Away from their homeland, the main contribution of the RCAF to the war effort was in Europe. The first RCAF squadron to reach the UK, in February 1940, was number 110 squadron operating from RAF Odiham with Lysanders. They were followed, in June 1940, by number 1 squadron equipped with Hurricanes. During the Battle of Britain, this squadron was the only Dominion squadron to fly their own aircraft, all other Dominion squadrons flying RAF owned aircraft.

However, prior to the arrival of the RCAF squadrons, the RAF had it's own 'Canadian' squadron, number 242, formed in 1939. This squadron achieved distinction with it's Hurricanes right from it's earliest days, operating in support of the evacuation of Dunkirk and the Battle of Britain. the first victory to a Canadian was gained by Squadron Leader Gobeil, RAF of 242 sqn. in May 1940.

In March and April 1941, more RCAF squadrons arrived in the UK and in all, the RCAF contribution to the European war amounted to 15 bomber squadrons, 20 fighter squadrons and 5 Coastal Command squadrons. This was in addition to the many thousands of Canadians who crossed the Atlantic to join and fly with the RAF itself.

In addition to the European theatre, The RCAF were active with the Desert air force in North Africa, the defence of Malta as well as in Borneo, Ceylon and the Far East against the Japanese.

More than 232,500 men and 17,000 women served with the RCAF in both home defence and further afield and by the end of the war, Canadian personnel accounted for a quarter of the whole RAF order of battle. The RCAF had grown to become the third largest air force in the world. However they paid a terrific price. 17,100 Canadians airmen gave their lives in the service of their country. In Bomber Command alone the Canadians lost 9,980 personnel killed or missing in action.