Abolitionists in the Americas and in Europe became vocal opponents of the slave trade throughout the 19th century. The importation of slaves to the colonies was often outlawed years before the end of the institution of slavery itself. It was well into the 19th century before many slaves in the Caribbean were legally free. The trade in slaves was abolished in the British Empire through the Abolition of the Slave Trade Act in 1807. Men, women and children who were already enslaved in the British Empire remained slaves, however, until Britain passed the Slavery Abolition Act in 1833. When the Slavery Abolition Act came into force in 1834, roughly 700,000 slaves in the British West Indies immediately became free; other enslaved workers were freed several years later after a period of forced apprenticeship. Slavery was abolished in the Dutch Empire in 1814. Spain abolished slavery in its empire in 1811, with the exceptions of Cuba, Puerto Rico, and Santo Domingo; Spain ended the slave trade to these colonies in 1817, after being paid £400,000 by Britain. Slavery itself was not abolished in Cuba until 1886. France abolished slavery in its colonies in 1848.