The Royal Air Force (RAF) is the air force of Britain. It was formed in 1918 by a merger of the Royal Flying Corps (RFC) and the Royal Naval Air Service (RNAS). DIvided between Fighter Command and Bomber Command, the RAF was a vitally important factor of World War II. Fighter Command won the Battle of Britain in 1940 and, from 1941 to 1945, Bomber Command was in frequent operation over enemy territory.