No. 40 Wing formed part of the Royal Air Force (RAF) Palestine Brigade during World War I and immediately after. It was established in October 1917 as 40th (Army) Wing, Royal Flying Corps (RFC), and become part of the RAF in April 1918, when the RFC merged with the Royal Naval Air Service. The wing played a major part in the Battle of Megiddo, the last great offensive against the Ottoman Empire, in September 1918. It was disbanded in April 1920.