In just eight days thousands of British civilians were killed and wounded, and large areas of London, particularly East London, were in ruins. But with the Luftwaffe’s focus on London, Dowding’s early warning system returned to peak efficiency, and RAF Fighter Command’s airfields were repaired, its pilots rested, and its planes fixed and properly maintained.

On 14 September 1940, Hitler postponed the invasion one last time, and decreed that if the RAF wasn’t destroyed within the week, the invasion of Britain would be postponed indefinitely. The next morning Herman Goering, convinced the RAF was on its last legs, called for a maximum effort. British radar picked up a formation of German planes over France that was so large it was taking longer than normal to form up. This gave Air Marshal Dowding time to organize the set piece battle he craved since July.

At 0700 as the Germans were enroute, Winston Churchill departed London to the relative safety of the 11 Group airfield at Uxbridge where he would observe the coming battle. 11 Group put up all of its fighters to meet the attack and Churchill asked “What other reserves have we?” 11 Groups commander, Keith Park replied tersely, ‘We have none, sir.”

That wasn’t entirely accurate. When the Germans took so long to form up this gave 12 Group to the north time to form their vaunted “Big Wings”. All told the RAF put up 625 fighters to meet 1120 Luftwaffe fighters and bombers over London and southern England. It was an apocalyptic air battle that lasted all day, with fighters on both sides fighting, landing, immediately rearming and refueling, and then heading back into the battle. Some British pilots did this four and five times. When evening came and the wreckages were counted, the RAF lost 43 fighters and the Luftwaffe lost 136 planes of all types.

But it wasn’t the losses that shocked the Germans, they were completely astonished by the RAF’s response. Like all totalitarian regimes, the Germans had problems with math and routinely made overly positive assessments of their operations to show progress. Just that morning the pilots were briefed that the RAF had only 250 fighters left in the country with just 150 covering London: the Luftwaffe pilots went into battle assuming they had an 8 to 1 advantage.

Luftwaffe planners and commanders tried to excuse away the large numbers of RAF fighters, but the pilots’ eyes did not deceive them and they talked: the British had no less than 500 up at any time. Goering was lying to them. Particularly demoralizing was a five squadron 12 Group Big Wing that descended upon a bomber formation and nearly wiped it out, leaving only a few stragglers…almost as if they were deliberately left alive to tell the tale.

The Battle of Britain continued for another three weeks, but it was anti-climactic after 15 September and the Luftwaffe switched increasingly to safer night raids. On 17 September, Hitler postponed Operation Sealion indefinitely, and switched his attention to the planning for next spring’s offensive: Operation Barbarossa, the Invasion of the Soviet Union.