It was not the heaviest day’s fighting. On three other days, more planes were shot down. But 15 September was the decisive day – the day the Germans realised they had lost the Battle of Britain. Military Times tells the story.

The WAAF girls in the operations room at Uxbridge were knitting, reading, or chatting. The huge gridded map-table showing southern England, the Channel, and the opposite coast was empty. Air Vice-Marshal Keith Park, commander of 11 Group, Fighter Command, was playing host to Prime Minister Churchill, who was sitting in one of the observation galleries.

It was 11 o’clock on Sunday 15 September 1940. Outside Park’s command-and-control bunker, the weather was warm with a mix of cloud and sunshine. The people of Kent and Sussex were going to church, preparing Sunday lunch, or just sitting out in the garden.

Then, at 11.04 am, came the first report: the Chain Home radar station at Dover had detected 40-plus enemy aircraft in the Calais-Boulogne area. The intelligence was filtered through Stanmore Park, Fighter Command HQ, and forwarded to Uxbridge with the designation ‘hostile’.

The WAAFs adjusted their headphones. The first marker-block was prepared and raked into position on the map-table. The Dover radar operators had picked up a formation of Messerschmitt Me 109 fighters.

Within ten minutes, three more marker-blocks had joined the first. One represented 25 Dornier Do 17 bombers. The others were further flotillas of Messerschmitts. One would provide close escort for the bombers, another would fly extended cover, and the third was on a ‘free hunt’ for enemy fighters. Altogether, there were about 120 incoming German aircraft.

The noon-day attack

The Dorniers’ target was London, but it had been chosen because Fighter Command would have to commit its fighters to aerial combat in order to defend it. The real aim was to destroy Hurricanes and Spitfires. German intelligence was convinced that Fighter Command was haemorrhaging badly and close to collapse. If true, Operation Sealion, the invasion of Britain, might yet be launched in autumn 1940.

Park, alongside his senior fighter controller, Wing Commander Lord Willoughby de Broke, now had to make a series of critical, close-call decisions. The enemy bombers were the target, but to get at them the enemy fighter protection would have to be stripped away. London was at the limit of the Messerschmitts’ range. If they could be drawn into high-speed aerial combat on the approach, they would consume fuel and be forced to turn for home before the Dorniers could complete their mission, leaving the German bombers unprotected against direct fighter attack.

But Park and de Broke needed to economise on force. If they committed everything too soon, they risked having their squadrons on the ground refuelling and rearming when a second wave came over. And the timing had to be right. Scramble too early, and their fighters would be wasting fuel waiting for the enemy. Too late, and they would fail to climb high enough to reach a good attacking position.

Two squadrons were scrambled at Biggin Hill (20 Spitfires). More blocks appeared on the map-table. Ten minutes later, six more squadrons were sent up from Northolt, Kenley, and Debden (68 Hurricanes). Five minutes more, and another three squadrons were ordered up from Hornchurch (12 Spitfires) and North Weald (20 Hurricanes). At the same time, Park phoned for right flank support from 10 Group, and for cover for his northern airfields from 12 Group.

‘Hello, Gannic Leader. Gannic Leader. Carfax calling. 200-plus coming in over Red Queen. Vector 120. Angels 25. Watch for the snappers above.’

‘Tally-ho right, Gannic. Here they come, chaps. Okay, boys, let’s go!’

As 72 and 92 Squadrons from Biggin Hill dived on the German bombers just before noon, lights lit up on the board at Uxbridge indicating ‘engaged’. 253 and 501 Squadrons from Kenley were also closing, approaching from directly in front at the same height, aiming for a head-on attack. Soon there were more: 229 and 303 Squadrons from Northolt.

The sky above mid-Kent became a swirling mêlée of fighters closing, banking, and twisting. The commonplace image of dogged duels between opposing pilots is myth. Any pilot who became obsessive about an opposing fighter was likely to be jumped from behind by another. The reality was high-speed attack, preferably from above and behind, a machine-gun burst of two or three seconds, a sudden lurch sideways to avoid collision, and then off and away to another part of the sky.

The first attack on the German formation by five squadrons was scrappy and indecisive. Ten minutes later, the second attack, this time by four squadrons, went in. Again, there were few kills, and the bombers kept formation and pressed on to the edge of London.

Dorniers over Battersea

But the first two waves had done their work, drawing the enemy fighters into combat over Kent and running down their fuel. As the Messerschmitts headed for home, the Dorniers found themselves on their own as they began their bombing run over Battersea’s complex of railway choke-points. To meet them, Fighter Command had concentrated 12 squadrons over and close to London, a total of 127 fighters against a bomber force one-fifth the size. Of these, five squadrons, no less than 55 fighters, entered the battle as a single ‘big wing’ formation, flying in from 12 Group air-stations north of London, commanded by legless legend Douglas Bader.

Fighter Command was supposed to be on the brink of collapse. Now the sky was full of Hurricanes and Spitfires. And the morale of their pilots was beyond question. Some of the attacks were ferocious. Sergeant Ray Holmes, spotting a lone Dornier ahead, launched a head-on attack in his Hurricane. When he ran out of ammunition, he held his course, diving at 400 mph, and rammed the enemy aircraft in mid-air.

The Dornier’s entire tail unit broke away. The nose dropped, and as the wreck plunged downwards, both outer wings snapped off, and two bombs and a crate of incendiaries smashed through the fuselage.

Holmes’ Hurricane was also wrecked, but he was able to bail out and parachuted to safety.

British fighters harried the Dorniers as they ran for home. Those that broke formation and straggled, having lost their way or suffered too much damage, were easy prey for the swarms of Hurricanes and Spitfires. But 15 of the original 25 held together, protected by the defensive cross-fire of their multiple guns, and by fighters of the withdrawal escort force of Me 109s now coming into action for the first time. Six were shot down. Four others straggled but made it back to France.

The last of the raiders had passed the English coast by 12.45. The all-clear sounded. Uxbridge relaxed.

The mid-afternoon attack

The lull was brief. An hour later, the coastal radars picked up the first evidence of the second wave. As the marker-blocks stacked up on the map-table, it was soon clear this was bigger. Even so, early reports of enemy strength underestimated by half.

They came over Dungeness shortly after 2 o’clock. The bombers were massed in five columns, three in the front line, two in the second. The front columns were spaced 5 km apart, the rear columns 5 km behind the leaders. In all, there were 114 bombers, a mix of Dornier Do 17s and Heinkel He 111s. Each column was protected by a Gruppe of about 30 Me 109s flying close escort, while a further five Gruppen were deployed as free-hunting patrols. In total, 475 German aircraft were approaching London in tight battle order. Their target: the docks.

Between 2 and 2.30 pm, Park ordered three scrambles, first of eight squadrons, then of 11, finally of his remaining two. No. 11 Group, Fighter Command, charged with the defence of London and the South-East, then had every one of its serviceable aircraft in the air. Even so, it was outnumbered 3:2 in fighters alone.

‘I become conscious of the anxiety of the commander, who now stood still behind his subordinate’s chair,’ Churchill later recalled. ‘Hitherto I had watched in silence. I now asked: “What other reserves have we?” “There are none,” said Air Vice-Marshal Park. In an account which he wrote about it afterwards, he said that I looked ‘very grave’. Well I might. What loses should we not suffer if our refuelling planes were caught on the ground by further raids of ‘40-plus’ or ‘50-plus’! The odds were great; our margins small; the stakes infinite.’

The form of the noonday battles now repeated itself, but on a grander scale. The first clashes were over Romney Marsh, where 27 Spitfires engaged the escorting Messerschmitts. The second was over The Weald, where 23 Hurricanes charged head-on and got in among the Dorniers of the right-hand lead column. They were soon joined by another 14. The ferocity of the British fighter attacks produced two mid-air collisions. Both were accidental, but the German bomber crews who witnessed them were traumatised by the apparent fanaticism of their opponents.

Bombs on the East End

As before, the main battle took place in front of London, as 19 fresh squadrons, 185 Hurricanes and Spitfires, joined the attack. Even so, more than 100 bombers were still in formation for their bombing run as they came over East London. Cloud obscured the docks, but bombs rained down on West Ham’s crowded rows of terraced houses.

As the bombers turned for home, the stragglers were picked off. Attacks on the main formations, by contrast, remained hazardous. Leutnant Roderich Cescotti, piloting a He 111, watched awestruck as a Spitfire dived on his bomber formation. An Me 109 got onto the enemy fighter’s tail and sprayed it with hits, but the Spitfire continued to dive, blasting Cescotti’s Heinkel with its eight machine-guns, then pulling away over the top.

The Heinkel had more than 30 hits, but none serious, and it got home. The Spitfire dived into the ground near Maidstone. Pilot Officer Arthur Pease was still inside the cockpit. ‘The action lasted only a few seconds, but it demonstrated the determination and bravery with which the Tommies were fighting over their own country.’

At 3.25 pm, the first of Park’s squadrons reported that it had landed, refuelled, rearmed, and was again ‘At Readiness’. Others quickly followed. The crisis had lasted for about an hour. Many German bombers had got through. Cloud had done more to reduce their effectiveness than British fighter attack. But the bombers had always been bait: the real measure of the battle was the balance of losses.

The Luftwaffe had lost 56 aircraft, 5.5% of the number committed to the two daylight raids of 15 September. The RAF lost 28.

What made 15 September decisive – the reason it is celebrated as ‘Battle of Britain Day’ – is that the action on that day destroyed the morale-sustaining Luftwaffe myth that Fighter Command was close to breaking-point. By flying 707 daylight sorties, by shooting down one German plane for every 12 British fighters in the air, and by engaging relentlessly, ferociously, sometimes even suicidally, the young Hurricane and Spitfire pilots demonstrated Fighter Command’s undiminished resilience after two months of intensive aerial combat.

Soon after 15 September, Operation Sealion, the planned invasion of Britain, was downgraded to a bluff. The war against Britain became a siege. Bombing from the air and blockade by U-boat was henceforward the German strategy for victory in the West.