In the 18th century AD, West African slaves were used to work the sugar plantations of the West Indies. Ports like Bristol and Liverpool thrived on the slave trade. Slaves were packed into the holds of ships in chains, many dying on the voyages and the plantation owners used them like beasts. In 1787, Evangelicals and Quakers, who considered the trade immoral and inhuman, helped to found the Society for the Abolition of the Slave Trade.

They were joined by the Member of Parliament (MP) William Wilberforce in 1788. He had undergone a religious conversion and was able to persuade his friend William Pitt, the Prime Minister, to back a campaign to suppress the trade. In spite of hundreds of petitions, those with an economic interest in slavery were able to defeat the campaigners.

The campaign was renewed in 1804, and in 1807 the government agreed to support an abolition bill, which was forced through the Lords. The campaigners next turned to abolishing slavery throughout the British Empire. The Anti-Slavery Society was founded in 1823 and had strong support in Parliament. As well as Wilberforce, MPs included Henry Brougham and the historian Thomas Macaulay. The bill abolishing slavery in the Empire was passed in 1833.