- Theatre: United Kingdom
- Dates: June to September 1940
- Location: Britain - the skies above the Southern Counties and the Channel
- Outcome: British victory, forcing Hitler to postpone indefinitely his plans to invade England
- Note: The Battle of Britain marked the first major use of radar, which strengthened British defensive capabilities enormously and was a significant contributor to eventual victory.
- Britain: RAF Fighter Command under Air Chief Marshal Sir Hugh Dowding, based mainly in south east England
- Germany: Luftflotten 2 under Field Marshal Albert Kesselring, based in north east France; Luftflotten 3 under Field Marshal Hugo Sperrle, based in the Low Countries
Following the evacuation of the British Expeditionary Force (BEF) from Dunkirk, Hitler issued a directive on 16 July 1940 ordering the preparation and, if necessary, the execution of a plan for the invasion of Great Britain, codenamed Operation Sealion.
Britain retained naval superiority and Hitler knew an amphibious invasion of the British Isles would only be possible if Germany could establish control of the air in the battle zone. The German High Command launched a campaign to gain air superiority over southern England and to knock British morale.
On paper, the Luftwaffe had a clear advantage. They entered the battle with around 1,300 bombers and dive-bombers, and about 900 single-engined and 300 twin-engined fighters - significantly more than Fighter Command's 600 planes.
But the Luftwaffe was hampered by a lack of any consistent plan of action. It tried to establish a blockade by destroying British shipping and ports, attempted to destroy Britain's Fighter Command through combat and the bombing of ground installations, and also attacked London and other important cities.
In addition, the British forces were well prepared. Radar early warning technology, the most advanced and the most operationally adapted system in the world, gave Fighter Command adequate notice of where and when to direct its forces to repel German bombing raids.
The Spitfire, though still in short supply at the time, was arguably the best intercepting fighter in the world and proved deadly against the German bombers, which lacked the bomb-load capacity to strike permanently devastating blows. German dive-bombers were extremely vulnerable to being shot down by British fighters, and fighter cover was only partially available since the German fighter aircraft were operating at the limit of their flying range over England.
The German air attacks were initially focused on British shipping, ports and airfields along the English Channel. In June and July 1940, as the Germans gradually redeployed their forces, the air battle moved inland.
On 2 August, the Luftwaffe chief, Reichsmarschall Hermann Göring, issued the Adlertag (Eagle Day) directive, a plan of attack in which a few massive blows from the air were to destroy British air power and so open the way for the invasion of Britain.
This intensive phase began on 8 August. The Germans launched bombing raids involving up to 1,500 aircraft a day and directed them against the British fighter airfields and radar stations. By late August the Germans had lost more than 600 aircraft and the RAF only 260, but the RAF was rapidly losing badly needed fighters and experienced pilots and its effectiveness was further hampered by the bombing damage done to its radar stations.
At the beginning of September the British retaliated with a bombing raid on Berlin, provoking Hitler into redirecting Luftwaffe attacks from Fighter Command installations to London and other cities. This gave the RAF a much-needed breather, but intensified the Blitz on British cities.
By mid-September Britain had effectively won the Battle of Britain, denying the Luftwaffe air superiority by shooting down German bombers faster than they could be rebuilt. On 17 September, Hitler postponed Operation Sealion 'until further notice'.