German bombers and fighters struck Channel convoys and southern England, marking what British historians consider the start of the Battle of Britain. Hermann Göring believed air superiority could force Britain's surrender or clear the way for Operation Sea Lion. Instead, RAF Fighter Command, aided by radar and Ultra intelligence, ground down German losses through the summer, delivering Hitler his first major defeat.
Radar stations along England's coast gave RAF controllers something no air force had ever had before: minutes of warning before an attack arrived. On July 10, that early-warning chain was tested in earnest as German aircraft, based in newly occupied France and the Low Countries, began probing raids meant to strangle British shipping and lure Fighter Command into a war of attrition.
Winston Churchill, only weeks into his premiership, understood the stakes with unusual clarity. He later wrote that never was so much owed by so many to so few, a line that would define the summer's mythology. But on this day the outcome was far from certain; France had just fallen, and Britain stood essentially alone in Western Europe.
What made the difference was a system, not just pilots. Chain Home radar, the Dowding system of centralized control, and Polish, Czech, and British aircrews flying Hurricanes and Spitfires combined to inflict disproportionate losses on the Luftwaffe. By October, Hitler had postponed the invasion of Britain indefinitely, and the battle entered legend as the first campaign fought and lost entirely in the air.