When Columbus visited Trinidad in 1498 the island was inhabited by Arawak Indians. Tobago was occupied by the Caribs. Trinidad remained a neglected Spanish possession for almost 300 years until it was surrendered to a British naval expedition in 1797. The British first attempted to settle Tobago in 1721 but the French captured the island in 1781 and transformed it into a sugar-producing colony. In 1802 the British acquired Tobago and in 1899 it was administratively combined with Trinidad. When slavery was abolished in the late 1830s, the British subsidized immigration from India to replace plantation labourers. Sugar and cocoa declined towards the end of the 19th century. Oil and asphalt became the main sources of income. On 31 Aug. 1962 Trinidad and Tobago became an independent member of the Commonwealth. A Republican Constitution was adopted on 1 Aug. 1976.