Six days into the critical phase of the Battle, during the Luftwaffe's direct assault on 11 Group's sector stations, Fighter Command flew 1,054 sorties, its largest daily number yet. The Germans put up 1,345, their biggest daylight effort for a fortnight. At this point, the tempo of combat was increasing daily.
Feint attacks against coastal shipping began soon after dawn to be followed by the first main raid of the day when, at 10.30am, three waves totalling 220 aircraft began flying in across Kent and Sussex at 30 minute intervals. A period of intense, and somewhat confused, fighting ensued, during which all of 11 Group's fighters were in the air and ten squadrons in action.
With no respite, the home defences faced the next onslaught at 1.30pm as successive waves of bombers came in over southern Kent. Several local radar stations were out of action due to power failure from morning bomb damage and only five squadrons were alerted to intercept. Action was continuous until 4.00pm when the third and most significant raid of the day approached. Biggin Hill sector station was hit heavily. The bombing was concentrated among the airfield buildings, where one of the last four surviving hangars and other important structures were destroyed. Most telephone lines and gas, electricity and water mains were cut. Attacks were also made on the Vauxhall factory at Luton, which sustained substantial damage, and the Handley Page Halifax bomber production line at Radlett which did not.
This day saw the British experience their heaviest fighting so far. A total of 22 fighter squadrons had seen action, most at least twice and some up to four times. Their exertions easily exceeded the events of 15 August in intensity.