In May, 1940, RCAF No. 1 Fighter Squadron arrived in Britain under the command of Squadron Leader E.A. McNab. After a few weeks training the squadron began operations August 19, 1940, at a time when the Luftwaffe's attacks on southern England were increasing in intensity. The first few days only resulted in fruitless scrambles; then on August 26, the Canadian Hurricane pilots finally encountered a formation of Dornier 215 bombers, three of which they destroyed. In the next eight weeks the Squadron's count stood at 31 enemy Aircraft definitely destroyed and 43 more probably destroyed or damaged. Three pilots had been killed in action - the RCAF's first combat casualties.

The three most successful fighters, S/L McNab, F/L G.R. McGregor, and F/O B.D. Russel, were awarded the Distinguished Flying Cross and thus became the first members of the RCAF to be honoured for their service.