July 10, 1940 the Battle of Britain begins. This was a precursor to Operation Sea Lion, Hitler's plan to capture England. But in order for him to land troops on British soil, he first had to control the air. This was the task of the Luftwaffe. The Luftwaffe's attack force consisted, at the beginning, of around 2000 aircraft including a large proportion of Messerschmitt fighters, while the RAF only had about half that number of planes in Hurricanes and Spitfires. Outnumbering the British almost 2 to 1 the German Luftwaffe planned to attack RAF bases, then seaports and finally commence their ground assault. With nowhere else to turn, the British turned to Canada for support. Canada began to produce Hurricane fighters and train pilots to defend Britain.
The Canadian fighter group 242 began to take a powerful role in the battle of Britain. This group shot down huge numbers of Messerschmitts while the British fighters were regrouping. Their only major loss was when a group of Messerschmitt 109s flew out of the sun in an ambush and shot down nine of them. The battle of Britain took an important turn when a stray German bomber came under attack from flak guns, dropped her bombs to reduce weight but didn't realize that he was flying over London, a target made off limits by Hitler. In retaliation, the Allies began to bomb German cities. With Hitler's subsequent order to bomb British cities, the pressure on British airbases and radar stations was relieved. This gave the RAF time to regroup and it began to achieve victories. German air losses eventually became so great that Hitler, with his attention now more focussed on the forthcoming invasion of Russia, was forced to give up his campaign and Operation Sea Lion was postponed indefinitely.