The Marine Branch (1918-1986) was a branch of the Royal Air Force (RAF) which operated watercraft in support of RAF operations. Just days after the creation of the RAF itself, the Marine Craft Section (MCS) was created with the transfer of Royal Navy Air Service (RNAS) vessels and personnel to the new service. Originally tasked with the support of RNAS, and later RAF, seaplanes, Marine Craft Section was to achieve its greatest size during the Second World War, and achieved fame for its role in air-sea rescue operations. After the war MCS was granted full branch status on 11 December 1947, however post war the role of the new branch became greatly reduced with the end of the British Empire, the withdrawal of flying boats from service, and the increasing use of helicopters in air-sea rescue.