 Innovations at the site included the world's first air traffic control and the first airport terminal.During World War II the airport was named RAF Croydon as its role changed to that of a fighter airfield during the Battle of Britain; and in 1943 RAF Transport Command was founded at the site, which used the airport to transport thousands of troops into and out of Europe.After World War II, its role returned to civil aviation, but the role of London's primary international airport passed to London Heathrow Airport.