Rapier is a British surface-to-air missile

Surface-to-air missile

A surface-to-air missile or ground-to-air missile is a missile designed to be launched from the ground to destroy aircraft or other missiles...

 developed for the British Army

British Army

The British Army is the land warfare branch of Her Majesty's Armed Forces in the United Kingdom. It came into being with the unification of the Kingdom of England and Scotland into the Kingdom of Great Britain in 1707. The new British Army incorporated Regiments that had already existed in England...

 and Royal Air Force

Royal Air Force

The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

. Entering service in 1971, it eventually replaced all other anti-aircraft weapons in Army service; guns for low-altitude targets, and the English Electric Thunderbird

English Electric Thunderbird

The English Electric Thunderbird was a British surface to air missile produced for the British Army. The Thunderbird was primarily intended to attack higher altitude targets at ranges of up to thirty miles or so. AA guns were still used for lower altitude threats...

, used against longer-range and higher-altitude targets. As the expected air threat moved from medium-altitude strategic missions to low-altitude strikes, the fast reaction time and high maneuverability of the Rapier made it more formidable than either of these weapons, replacing most of them by 1977.