Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Sea Slug was a first generation surface-to-air missile designed by Armstrong Whitworth (later part of the Hawker Siddeley group) for use by the Royal Navy. It came into operational service in the 1960s and was still in use at the time of the Falklands War. Sea Slug was intended to engage high-flying targets such as reconnaissance aircraft or bombers before they could launch stand-off weapons. Later improvements meant that it could also be used against ships. Work on what became Sea Slug began in 1949 under ''Stage 1'' of the Royal Navy''s post-war missile program. The weapon was intended to counter high-altitude, nuclear-armed bombers before they could release their weapons. Work was based on an earlier programme known as "LOPGAP" (Liquid Oxygen / Petrol Guided Anti-aircraft Projectile) and a Victory Ship specially converted into prototype escort ship, HMS Girdle Ness, was procured for developmental work. The original system differed in having a triple launcher.