The Mount Batten flying boat base, near Plymouth in southern England, was first established as Royal Naval Air Service station Cattewater in February 1917. It was transferred to the Royal Air Force (RAF) when that service was created in April 1918 and remained operational until March 1922 when it was placed in reserve. It became operational again in September 1928 and was renamed RAF Station Mount Batten on 1 October 1929. The station operated throughout the Second World War and was home to both Royal Australian Air Force flying boat squadrons for varying periods. Operating from Plymouth Sound proved to be a challenge for pilots as it was always full of ships, and the ships and Plymouth itself were protected by barrage balloons. Mount Batten ceased to be an operational station on 31 October 1945 but various RAF marine maintenance and training units occupied it up until it was finally closed in July 1992.