region in the early 17th century, such as slaves from Senegal living on St Kitts in the mid-1600s. By 1672 a slave depot existed on the island of Nevis, serving the Leeward Islands. While the time of African arrival in Anguilla is difficult to place precisely, archival evidence indicates a substantial African presence of at least 100 enslaved people by 1683; these seem to have come from Central Africa as well as West Africa. The slaves were forced to work on the sugar plantations which had begun to replace tobacco as Anguilla's main crop. Over time the African slaves and their descendants came to vastly outnumber the white settlers. The African slave trade was eventually terminated within the British Empire in 1807, and slavery outlawed completely in 1834. Many planters subsequently sold up or left the island. During the early colonial period, Anguilla was administered by the British through Antigua; in 1825, it was placed under the administrative control of nearby Saint Kitts. Anguilla was federated with St Kitts and Nevis in 1882, against the wishes of many Anguillans. Economic stagnation, and the severe effects of several droughts in the 1890s and later the Great Depression of the 1930s led many Anguillans to emigrate for better prospects elsewhere. Full adult suffrage was introduced to Anguilla in 1952. After a brief period as part of the West Indies Federation (1958–62), the island of Anguilla became part of the associated state of Saint Kitts-Nevis-Anguilla with full internal autonomy in 1967. However many Anguillans had no wish to be a part of this union, and resented the dominance of St Kitts within it. On 30 May 1967 Anguillans forcibly ejected the St Kitts police force from the island and declared their separation from St Kitts following a referendum. The events, led by Atlin Harrigan and Ronald Webster among others, became known as the Anguillan Revolution; its goal was not independence per se, but rather independence from Saint Kitts and Nevis and a return to being a British colony. With negotiations failing to break the deadlock, a second referendum confirming Anguillans' desire for separation from St Kitts was held and the Republic of Anguilla was declared unilaterally, with Ronald Webster as president. Efforts by British envoy William Whitlock failed to break the impasse and 300 British troops were subsequently sent in March 1969. British authority was restored, and confirmed by the Anguilla Act of