The Atlantic slave trade began in the 15th century, when Portuguese explorers first brought enslaved Africans to Europe. The trade then grew rapidly in the 16th and 17th centuries, as European powers established colonies in the Americas and the demand for labor on plantations increased. The transatlantic slave trade reached its peak in the 18th century, when an estimated 12 million Africans were forcibly transported to the Americas. The trade began to decline in the 19th century, as a result of the Haitian Revolution, the British abolition of the slave trade in 1807, and the American Civil War. The Atlantic slave trade officially ended in 1867, when the Portuguese Empire abolished slavery in its colonies.