The Vote That Banned Britain's Slave Trade

The vote was not even close. On the evening of February 23, 1807, after ten hours of debate in the House of Commons, members voted 283 to 16 in favor of ending the British slave trade. For the abolitionists who had labored for two decades, the roar of approval was the sound of a wall finally breaking.

But the bill was not yet law. It still had to pass the House of Lords, and then receive the signature of the king. On March 25, 1807, King George III gave the Slave Trade Act his royal assent. It became illegal, from May 1, 1807, for British subjects and British ships to take part in the trade in enslaved Africans.

To understand what that meant, consider the scale of what had come before. British ships dominated the transatlantic slave trade, carrying — in peak years — some forty thousand enslaved men, women, and children across the Atlantic in the horrific conditions of the middle passage. Of an estimated 11 million Africans transported into slavery, about 1.4 million died during the voyage. The trade was not a side business of empire: the triangular trade that carried British goods to Africa, enslaved people to the Americas, and slave-grown sugar, tobacco, and cotton back to Britain accounted for roughly four-fifths of Britain's foreign income.

Against all that money and power stood William Wilberforce, the diminutive Yorkshire MP who had taken up the cause of abolition in 1787. For twenty years he introduced bill after bill, gathering evidence with the campaigner Thomas Clarkson, facing down the shipping interests, the plantation lobby, and governments that kept finding reasons to delay. What finally broke the deadlock was politics: after the foreign secretary Charles James Fox — a backer of abolition — died in September 1806, Lord Grenville took up the cause in the House of Lords while Wilberforce led in the Commons. That February night, a tired Commons voted overwhelmingly for the bill. The Lords followed. And on March 25, the king's assent made it law.

The law was narrow in ways that matter. It abolished the trade — the buying and shipping of enslaved people — but not slavery itself. Enslaved people already held in British colonies remained enslaved; that fight would take another quarter century, until the Slavery Abolition Act of 1833. Enforcement, too, was a struggle: the Royal Navy's West Africa Squadron spent decades chasing slave ships.

But the date on the calendar mattered immediately. Because the Act took effect on May 1, 1807, British captains had a narrow window to make their last legal voyages. The Kitty's Amelia became the last British slave ship to leave under the old law — cleared out of Liverpool on April 27 and sailing for Africa on July 27, her voyage grotesquely legal because she had departed before the deadline.

Wilberforce did not live to see slavery itself abolished. But he did live to hear, in July 1833, that the bill to end it would pass Parliament. He died three days later — on July 29, 1833 — and was buried in Westminster Abbey.

The Slave Trade Act did not end human bondage, and no single law could have. What March 25, 1807 did was mark the first time a great trading nation had declared, in statute, that the buying and selling of human beings was a crime. The trade did not vanish overnight — but from that day, every British slave ship was breaking the law.

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