History of British Indian Ocean Territory

Uninhabited Prehistory

The Chagos Archipelago remained uninhabited throughout recorded history prior to European colonization, with no indigenous population ever documented. The remote coral atolls, lying over 1,500 km from the nearest continental landmass, were known to Arab and South Asian mariners but never permanently settled. European explorers charted the islands from the sixteenth century onward.

French Colonial Period

1783 – 1814

France claimed the Chagos Archipelago as a dependency of Mauritius (then Île de France) in the late eighteenth century, establishing coconut plantations worked by enslaved Africans. The islands, particularly Diego Garcia, served as a provisioning stop for vessels traversing the Indian Ocean. This era introduced the first permanent human habitation of the archipelago.

British Dependency Era

1814 – 1965

Britain acquired the Chagos Archipelago through the Treaty of Paris (1814) following the Napoleonic Wars, administering it as a dependency of Mauritius and later the Seychelles. Copra plantations continued to operate, sustaining a settled Chagossian community of several hundred people known as the Ilois. The islands remained an obscure imperial backwater until strategic considerations during the Cold War prompted a fundamental reassessment of their value.

BIOT Establishment

1965 – 1973

The British Indian Ocean Territory was formally created by Order in Council on 8 November 1965, detached from Mauritius and the Seychelles ahead of their respective independences. A secret agreement with the United States provided for the construction of a major joint military facility on Diego Garcia. Between 1967 and 1973, the entire Chagossian population was forcibly relocated, primarily to Mauritius, in one of the most controversial acts of British colonial administration in the postwar period.

Military Territory & Legal Disputes

1973 – present

Diego Garcia became a strategically critical joint UK-US naval and air support facility, used extensively during the Gulf War, the War in Afghanistan, and operations in Iraq. In 2000, the British High Court ruled that the expulsion of the Chagossians had been unlawful, though subsequent government Orders in Council again restricted resettlement, triggering prolonged legal battles. In 2024, the UK and Mauritius reached a landmark agreement in principle to transfer sovereignty of the archipelago to Mauritius, placing the territory's future status in question.