Hitler expected Britain to surrender after France fell. Instead, a few hundred RAF pilots — outnumbered and outgunned — fought Germany to a standstill and handed Hitler his first defeat.
After France fell in June 1940, Hitler expected Britain to accept peace terms. When Churchill refused, Germany planned Operation Sea Lion — the invasion of Britain — but set one condition: the Luftwaffe must first destroy the Royal Air Force. The air campaign that followed, fought entirely over British skies from July to October 1940, would determine whether England survived.
The numbers favored Germany. The Luftwaffe had roughly 2,550 aircraft against the RAF's 1,963. Germany had more experienced pilots and had just crushed the air forces of France, Belgium, and the Netherlands. But Britain had one critical advantage: radar. The Chain Home network of radar stations gave Fighter Command early warning of incoming raids, letting them direct limited resources precisely where they were needed.
At its peak, the battle was decided by a relative handful of men. Fighter Command had roughly 1,100 trained pilots at the start, and losses mounted faster than replacements could be trained. Churchill immortalized them in August 1940: 'Never in the field of human conflict was so much owed by so many to so few.' The pilots came from across the Empire and occupied Europe — 145 Poles, 127 New Zealanders, 112 Canadians, 88 Czechs.
Germany made a critical error in early September 1940. Goering switched the Luftwaffe's targeting from RAF airfields — which were genuinely close to collapse — to bombing London in retaliation for a British raid on Berlin. The Blitz was terrifying for Londoners, but it gave Fighter Command time to repair, regroup, and recover. The shift may have cost Germany the battle.
On September 15, 1940 — now commemorated as Battle of Britain Day — the Luftwaffe launched its largest assault, expecting to finally break the RAF. Instead they were met with massive resistance and suffered heavy losses. Within days, Hitler postponed Operation Sea Lion indefinitely. The invasion was never rescheduled. Britain would not fall.
The Battle of Britain was the first major German defeat of the war and proof that Hitler's forces were not invincible. It bought time for Britain to rearm, for American support to build, and for the Soviet Union to enter the war. Without it, there might have been no D-Day, no Allied coalition, no western front — the war's entire shape depended on the outcome over British skies in the summer of 1940.