After the war, the service was drastically cut and its inter-war years were relatively quiet, with the RAF taking responsibility for the control of Iraq and executing a number of minor actions in other parts of the British Empire.
The RAF underwent rapid expansion prior to and during the Second World War. Under the British Commonwealth Air Training Plan of December 1939, the air forces of British Commonwealth countries trained and formed "Article XV squadrons" for service with RAF formations. Many individual personnel from these countries, and exiles from occupied Europe, also served with RAF squadrons.
In the Battle of Britain, in the late summer of 1940, the RAF (Helped by multinational i.e. Polish, Czechoslovakian pilots and ground personnel) defended the skies over Britain against the German Luftwaffe, helping foil Hitler's plans for an invasion of the United Kingdom, and prompting Prime Minister Winston Churchill to say in the House of Commons on 20 August, "Never in the field of human conflict was so much owed by so many to so few".
During the Cold War years the main role of the RAF was the defence of the continent of Europe against potential attack by the Soviet Union, including holding the United Kingdom's nuclear deterrent for a number of years.
After the Cold War, the RAF was involved in several large scale operations, including the Kosovo War, the 2001 invasion of Afghanistan and the 2003 invasion of Iraq.
The Royal Air Force Museum is a museum dedicated to the history of aviation, and the Royal Air Force in particular. It is based at two sites, Colindale in north London, and Cosford, Shropshire.