1940 Climax of the Battle of Britain
The attempt by the Luftwaffe to destroy the Royal Air Force in order to win air superiority over the English Channel and pave the way for the invasion code-named Operation Sea Lion reached its peak in mid-September, 1940.
On September 15, the Germans launched a massive series of raids on London using 500-bombers, hoping to draw the RAF into a decisive combat with their 620 accompanying fighters. The plan was not a success; the disappointing results and high casualties would persuade the Germans to shift from targeting the RAF to night-time attacks on cities.
The above graphic has some interesting data. The contribution by the British Dominions to the supply of fighter pilots was significant but so was the role played by European exiles such as the Czechs and Poles. But why was the Belgian contingent so much higher than the French (who scarcely outnumbered American pilots whose country was not even at war)? Why were there so many New Zealanders in the air over London compared to Australians? Where was the RAAF at that time?
September 15 is still celebrated as Battle of Britain Day in the U.K.