The success of the first British airborne raid, Operation "Colossus", prompted the War Office to expand the airborne force through the creation of the Parachute Regiment, and to develop plans to convert several infantry battalions into parachute and glider battalions. On 31 May 1941, a joint army and air force memorandum was approved by the Chiefs-of-Staff and Winston Churchill; it recommended that the British airborne forces should consist of two parachute brigades, one based in England and the other in the Middle East, and that a glider force of 10,000 men should be created.