The Royal Air Force (RAF) is the United Kingdom's aerial warfare force. It was formed towards the end of the First World War on 1 April 1918. Following victory over the Central Powers in 1918 the RAF emerged as, at the time, the largest air force in the world. Since its formation, the RAF has taken a significant role in British military history. In particular, it played a large part in the Second World War where it fought its most famous campaign, the Battle of Britain.