The volcanic island was discovered by the Portuguese navigator, Joo Nova, on Ascension Day 1501, and was occasionally visited thereafter by ships. In 1701 William Dampier was wrecked on its coast, and during his time there discovered the only spring of fresh water the island contains. The Island was first occupied in 1815 by the Royal Navy at the time that they incarcerated Napoleon in his exile on nearby St. Helena. They did not want any rescue mission to use Ascension Island as a base to work from. A settlement, named George Town (now known as the Garrison), was made on the north-west coast. This was the best bay for the ships, but was some six miles from the only source of water at Dampier's Springs. The island was placed under the direct rule of the Admiralty, and was run as if it were a ship. It was governed by a naval captain under the command of the admiral superintendent at Gibraltar.
After the death of Napoleon it was realised that it would make an ideal depot of stores for the navy. It was visited once a month by mail steamers from the Cape. Previously, letters had been left by passing ships under one of the rocks. Later, the island became an important cable station and Cable and Wireless maintained a permanent office there.
After the First World War, the island finally passed from military to civil control. The Colonial Office made the island a dependency to be administered from the much more populous St. Helena in 1922.
An airbase was built on the island and it became an important refuelling station for the USAF and RAF. It's strategic significance and importance became apparent during the Falkland's War campaign as it became an important staging post for ships and aircraft en route to the theatre.