Finally there were the historic sugar colonies of the Caribbean, such as Jamaica and Barbados, acquired in the mid-seventeenth century. The massive commitment of British troops to the West Indies in the 1790s reflected fears that their very considerable value to Britain might be threatened either by internal slave revolt in the manner of St Domingue in 1791 or by external enemies. In the event, rather than losing ground, Britain made permanent territorial gains in Trinidad (from Spain) and on the South American mainland, in Demerara, Berbice and Essequibo (from the Dutch). To these were added - again during the French Wars - a wide range of other tropical territories, including Ceylon and Mauritius. In West Africa British possessions were limited to the settlement of Sierra Leone (a humanitarian venture begun in 1787, which was designed to serve the interests both of poor blacks from Britain and North America as well as freed slaves), and some scattered trading posts on the Gambia and Gold Coast.