After winning the Battle of France, the Luftwaffe sought to gain air superiority in the skies over Britain during the summer of 1940. The ensuing defence by the RAF against the onslaught of the Luftwaffe became known as the Battle of Britain. It was the first major campaign fought entirely by means of aerial combat. Initially, the Luftwaffe attacked shipping in the English Channel, and shipping ports such as Portsmouth and Plymouth. By August, they were concentrating their attacks on RAF airfields and ground installations. However, in a move that probably invited defeat for Germany in the battle, the Luftwaffe switched from bombing RAF targets to bombing major cities. This move allowed the airfields the time to recover and regroup, making the defence capabilities of Britain stronger.

By the summer of 1940, the RAF had approximately 9,000 pilots and 5,000 aircraft, most of which were bombers. By the 1st of July, the Commander of Fighter Command, Marshal Hugh Dowding could provide just 1103 fighter pilots - which came from the regular RAF squadrons, the Auxiliary Air Force squadrons and the Volunteer Reserve. Replacement pilots with little flight training and often no gunnery training suffered high casualty rates. Meanwhile, the Luftwaffe comprised 1450 fighter pilots, many with experience from the Spanish Civil Wars just a few years earlier. During the Battle of Britain, the Luftwaffe used four primary bombers. These were the Heinkel He111, Dornier Do17 and Junkers Ju88 for level bombing, and the Junkers Ju87 Stuka dive bomber. These were escorted by Messerschmitt Me109 and Me110 fighters. Defending Britain against the Luftwaffe were the Hawker Hurricane and Supermarine Spitfire squadrons of the RAF. While Britain successfully defended the air during the battle and repelled any invasion attempt by denying the Luftwaffe air superiority, losses were high on both sides of the battle. Between the official dates of the battle - 10th July to 31st October 1940 - 2936 fighter pilots took part n the battle on the British side, including 595 non-British pilots. These included 145 pilots from Poland, 127 from New Zealand, 112 from Canada, 88 from Czechoslovakia, 28 from Belgium, 32 from Australia, 25 from South Africa, 13 from France, 10 from Ireland, 7 from America, and 1 from each of Jamaica, Palestine and Rhodesia.

The Allied losses were 544 aircrew killed, 422 wounded and 1547 aircraft destroyed, while the Luftwaffe lost 2698 aircrew killed, and lost 1887 aircraft.

This key battle was considered the first crucial defeat for Germany. Had the Luftwaffe been successful in its aims, Germany could have invaded Britain, and had the invasion been successful, the outcome of the war could have been very different, with nowhere for the American Air Force to launch attacks on Germany from.