What 1940 air battle prevented a German invasion of Britain?

The 1940 air battle that prevented a German invasion of Britain was the Battle of Britain.

Fought mainly from 10 July to 31 October 1940, the campaign pitted Germany’s Luftwaffe against Britain’s Royal Air Force and Fleet Air Arm. Germany needed air superiority over southern England and the English Channel before launching Operation Sea Lion, its planned invasion.

British radar, the Dowding System, fighter control, aircraft production, and the defense of key airfields helped the RAF withstand sustained attacks. The Luftwaffe shifted from attacking Fighter Command’s infrastructure to bombing London, a change that gave some battered RAF bases time to recover. Germany ultimately failed to destroy Britain’s air defenses, and Hitler postponed the invasion.

The Blitz was the later, mainly nighttime bombing campaign against British cities, although the two periods overlapped. Operation Sea Lion was the invasion plan itself, not the battle that stopped it. The Battle of Britain is widely regarded as Nazi Germany’s first major defeat in World War II.