British abolitionism was a campaign, running from the late eighteenth century into the nineteenth, to end first the slave trade and then slavery itself across the British Empire. Quakers, evangelical Anglicans, former slaves, writers and members of Parliament built one of the first mass political movements in modern Britain. It won the Slave Trade Act of 1807 and the Slavery Abolition Act of 1833, and afterwards pressed other states to give up the trade.
Early voices and the courts
Before the 1770s few people in Britain spoke out against slavery. English Quakers and some evangelical groups had condemned it as un-Christian, and a handful of Enlightenment writers attacked it on grounds of natural rights. The decisive early moment came in the courts. In 1772 James Somersett, an enslaved man who had been baptised in London, faced being shipped to Jamaica for resale. Lord Mansfield ruled on 22 June that his detention could not be justified under English law, and the judgment was widely taken to mean that slavery had no legal footing in England. A Scottish court reached a similar conclusion in Knight v. Wedderburn in 1778. Neither ruling reached the colonies, where slavery rested on local statutes, and planters and merchants formed their own lobby in 1780 to defend their interests.
Organising a movement
In 1783 Quakers set up their first abolitionist body and presented a petition to Parliament. Four years later, in 1787, Thomas Clarkson, Granville Sharp and others set up the Society for the Abolition of the Slave Trade. Because Quakers, as Dissenters, could not sit in the Commons, the evangelical MP William Wilberforce led the cause in Parliament, while Clarkson travelled the country interviewing sailors in Bristol, Liverpool and London and setting up local committees. Campaigners used petitions, pamphlets, a boycott of slave-grown sugar, Josiah Wedgwood's medallion bearing the words "Am I Not A Man And A Brother?" and the plan of the slave ship Brookes. The memoir of the formerly enslaved writer Olaudah Equiano, which ran to nine editions in his lifetime, gave the campaign a powerful African voice. A petition of 1792 gathered some 400,000 signatures.
Ending the trade
The Commons voted in 1792 for gradual abolition of the trade, but the Lords held up the measure. Success finally came on 25 March 1807, when Parliament made the Atlantic slave trade illegal for British subjects, with a fine of £100 for each enslaved person found on a British ship. Smuggling continued, so the Slave Trade Felony Act of 1811, brought in by Henry Brougham, made trading a criminal offence; from 1827 it was treated as piracy. The Royal Navy's West Africa Squadron is credited with seizing roughly 1,600 slave ships and freeing about 150,000 Africans between 1808 and 1860. Freetown, the first settlement of Sierra Leone, became a home for freed people.
Emancipation
Slavery itself survived in the colonies after 1807. In 1823 campaigners founded the Anti-Slavery Society, and from 1825 women's anti-slavery societies multiplied, beginning in Birmingham. The Christmas rebellion of 1831 in Jamaica, led by Sam Sharpe, convinced many that there was no longer any middle way. The Slavery Abolition Act received royal assent on 28 August 1833 and took effect on 1 August 1834, though India was excluded and the freed people were bound to their former owners as "apprentices". Peaceful protests, beginning in Trinidad on the first day, helped cut the system short, and full freedom was granted on 1 August 1838, two years earlier than planned for many. Slave owners shared £20 million in compensation; the formerly enslaved received nothing.
After 1833
The British and Foreign Anti-Slavery Society, founded in 1839, held the first World's Anti-Slavery Convention in London in 1840 and campaigned against slavery abroad, including in the United States. It survives today as Anti-Slavery International. Historians continue to debate how far moral conviction or economic change drove abolition; in 1948 W. E. B. Du Bois argued that declining profits and imperial interests made Parliament readier to yield.
On our maps
Our 1783 and 1815 maps show the United Kingdom and its Caribbean colonies while slavery was still legal there; our 1878 map shows the empire after emancipation.