On this beautiful Sunday morning as the haze cleared, the radar plots picked up massed formations of German aircraft heading for England. Sixty Heinkels attacked RAF Biggin Hill and a further 48 Dorniers and Ju88s attacked Kenley. This was just the beginning - the fighter stations at Croydon, Hawkinge and West Malling were also attacked. All of these airfields were defended stoutly - 64, 111 and 615 Squadrons from Kenley defended their own airfield as well as Hawkinge. Whilst they were engaging the enemy, over 100 bombs fell on Kenley, temporarily putting it out of action so that some of the defenders were diverted to land at Croydon whilst repairs were carried out, although 64 Squadron managed to get down at their home airfield due to an improvised landing strip being marked out between the bomb craters. Croydon Airport had itself received some attention, with 19 bombs damaging hangars and outbuildings.
The attack on Biggin Hill was also stubbornly defended but here 32 and 610 Squadrons were scrambled on the initiative of the Station Commander, Group Captain Grice. This was due to the radar plots being overwhelmed with the sheer numbers of attackers but although the defending squadrons were ordered into the air at relatively short notice, they destroyed ten of the attacking German bombers which on this occasion merely added further craters to the airfield without destroying any aircraft on the ground.
The next assault on this day came in the early afternoon when the RAF airfields at Thorney Island and Gosport were attacked by Stuka dive bombers as was the Fleet Air Arm station at Ford, in Sussex and the radar installation at Poling, near Arundel in Sussex. This time the cumbersome Ju87 Stukas were routed by the defending RAF fighters of 43, 152 and 234 Squadrons, which destroyed seventeen out of the twenty five attacking aircraft. This was the final time that the Stukas took any meaningful part in the Battle of Britain - they had been suffering alarming levels of losses and had become a liability for the Luftwaffe, as well as a death trap for their crews.
The final attacks of the day came in the late afternoon when Croydon was attacked once again and twelve Me1o9s attacked RAF Manston from beneath the radar and destroyed two Spitfires on the ground as well as killing an airman and injuring fifteen others. The night saw bombing raids on Bristol and minelaying operations in the Thames Estuary and Bristol Channel.
So ended Sunday 18th August 1940; the Luftwaffe had lost a total of sixty nine aircraft against the RAF's thirty four plus another twenty nine on the ground. Whilst this meant the losses were about equal, when it came to air combat the losses were about 2:1 in the RAF's favour. Destroyed aircraft could be replaced quickly but pilots and aircrew could not and this was where the advantage remained with the British - the RAF's pilots who were not killed could bale out and be rescued over home territory whilst those from the Luftwaffe were either killed outright or taken prisoner.
This was a battle of attrition which the RAF was winning but the sheer numbers of the attackers meant that it would be a near run thing and it would take a blunder by Hitler when he ordered the switching of attacks from the RAF's airfields to London, to make the outcome certain.
On the 18th August 1940, this was all still in the future but this date will be remembered as the day when both sides in the Battle of Britain suffered the most material damage. As Alfred Price called his excellent book on the subject, this was The Hardest Day.
The Most Dangerous Enemy, Stephen Bungay - Aurum Press, 2000
The Hardest Day, Alfred Price - Arms & Armour Press, 1979
The Narrow Margin, Derek Wood with Derek Dempster - Hutchinson 1961