The Battle of Britain was a military campaign of the Second World War, in which the Royal Air Force (RAF) and the Fleet Air Arm (FAA) of the Royal Navy defended the United Kingdom (UK) against large-scale attacks by Nazi Germany's air force, the Luftwaffe. It was the first major military campaign fought entirely by air forces. The British officially recognise the battle's duration as being from 10 July until 31 October 1940, which overlaps the period of large-scale night attacks known as the Blitz, that lasted from 7 September 1940 to 11 May 1941. German historians do not follow this subdivision and regard the battle as a single campaign lasting from July 1940 to May 1941, including the Blitz.

The Luftwaffe was the aerial-warfare branch of the Wehrmacht before and during World War II. Germany's military air arms during World War I, the Luftstreitkräfte of the Imperial Army and the Marine-Fliegerabteilung of the Imperial Navy, had been disbanded in May 1920 in accordance with the terms of the 1919 Treaty of Versailles which banned Germany from having any air force.