http://en.wikipedia.org/wiki/Battle_of_Britain15 August was "The Greatest Day" when the Luftwaffe mounted the largest number of sorties of the campaign. Luftflotte 5 attacked the north of England. Believing Fighter Command strength to be concentrated in the south, raiding forces from Denmark and Norway ran into unexpectedly strong resistance. Inadequately escorted by Bf 110s, bombers were shot down in large numbers. As a result of the casualties, Luftflotte 5 did not appear in strength again in the campaign.