To the Germans, the Battle of Britain began on 13 August, Adlertag or "Eagle Day" as they called it. On this day, waves of strong attacks at different times over a ten hour period came in against Essex and Kent, Sussex and Hampshire.
Action was joined over the Thames Estuary at 6.30 in the morning as bombers headed for Eastchurch and Sheerness. Almost simultaneously, another formation heading for the Royal Aircraft Establishment at Farnborough and Odiham aerodrome was challenged over the Sussex coast. Just before midday a force of Messerschmitt 110s, which had taken off prematurely and flown on without the bombers it was supposed to escort, was savaged over Portland by fighters from 10 and 11 Groups.
Into the afternoon the action intensified as the morning's two-pronged thrust was repeated with attacks on Detling and Rochford airfields in the south east and Middle Wallop airfield and Southampton in Hampshire. Fighting began at approximately four o'clock on both flanks and a series of vigorous engagements ensued.
Including a night attack against the Nuffield factory at Castle Bromwich which produced Spitfires, the Luftwaffe mounted an impressive total of 1,485 sorties, two-thirds of them by fighters, over the twenty-four hour period. Fighter Command had flown 727 sorties in response.
The Germans' intention had been to probe the defences to see if they could pit equal resources against attacks widely separated. However, their substantial effort had met with only moderate success. Southampton had experienced some damage and the only airfields to suffer, Eastchurch and Detling, were Coastal Command stations thus leaving the fighter defences unimpaired. Three main objectives, Odiham, Farnborough and Rochford had been missed entirely. On the other hand, the day's operations had emphasised the difficulty the home defence had in meeting the Germans with forces large enough to inflict significant losses on them.