History

The Chagos islands were first discovered, uninhabited, in the 16th century. The French assumed sovereignty in the late 18th century and began to exploit them for copra, originally employing slave labour. By then, the Indian Ocean and its African, Arabian and Indian coasts had become a centre of rivalry between the Dutch, French and British East India companies for dominance over the spice trade and over the routes to India and the Far East. France, which had already colonised Réunion (called Isle Bourbon) in 1649, claimed Mauritius (Isle de France) in 1721; it subsequently took possession of the Seychelles group and the islands of the Chagos Archipelago.

During the Napoleonic wars Britain captured Mauritius and Réunion from the French. Under the treaty of Paris in 1814, Britain restored Réunion to France, and France ceded to Britain Mauritius and its dependencies, which comprised Seychelles and various other islands, including the Chagos Archipelago. All these dependencies continued to be administered from Mauritius until 1903, when the Seychelles group was detached to form a separate Crown Colony. The Chagos islands continued to be administered as a dependency of Mauritius until they were detached to become part of the British Indian Ocean Territory in 1965.

After the British Indian Ocean Territory had been created, the UK Government gave an undertaking to return the Chagos islands to Mauritius when they were no longer required for defence purposes. Since the 1980s, successive Mauritian governments have asserted a sovereignty claim to the islands, arguing that they were detached illegally.