The
Chagos Archipelago is an archipelago in the
Indian Ocean comprising the seven
atolls with over 1,000 individual islands, many very small, amounting to a total land area of . The islands were uninhabited until 1793, when the first successful colony was founded on Diego Garcia by
France.
Coconut plantations were established on many of the atolls and isolated islands of the archipelago. Initially the workers were enslaved Africans, but after 1840 they were freemen, many of whom were descended from those earlier enslaved. They formed a mixed culture called
Ilois or
Chagossians. Between 1810 and 1965, the islands were governed as part of the colony of
British Mauritius. In 1965, the British government separated the Chagos Archipelago from
Mauritius prior to Mauritius's independence, creating a new colony of the
British Indian Ocean Territory, from which they
expelled the entire Chagossian population, numbering about 2,000 people, to Mauritius and
Seychelles, in order to build a
Joint Military Facility of the
United Kingdom and the
United States on the largest island of the archipelago,
Diego Garcia. The only inhabitants were British and United States
military personnel, and associated
contractors, who as of 2018 figures, collectively number around 3,000. Since the 1980s, the Government of
Mauritius sought to gain control over the Chagos Archipelago. A February 2019
advisory opinion of the
International Court of Justice called for the islands to be given to Mauritius. Negotiations between the then Rishi Sunak-led Conservative UK government and Mauritius began in November 2022, and culminated in a treaty which was signed on 22 May 2025 under the
Keir Starmer-led Labour government to formally transfer the sovereignty of the territory to Mauritius should it come into effect, while the Diego Garcia military base remains under British control during a
99-year lease. The UK government expected the treaty to be ratified sometime in 2026. In March 2026,
Louis Olivier Bancoult, leader of the Mauritius-funded Chagos Refugee Group, stated his satisfaction with discussions with Mauritius's government regarding the UK-Mauritius treaty. In March 2026, the President of
Seychelles visiting as chief guest for the celebrations of Mauritius' 58th Independence Day, reiterated his government's support for the sovereignty of Mauritius over the Chagos. This recognition came a "fortnight after the Indian Ocean island nation suspended diplomatic ties with the
Maldives following the Maldivian government’s non-recognition of Mauritian sovereignty over the islands." == Formation ==