On March 25, 1807 the Slave Trade Act was passed by Parliament, abolishing the slave trade in the British Empire (though not abolishing slavery itself—baby steps, unfortunately.)
The Slave Trade Act was pushed forward by the Committee for the Abolition of the Slave trade, which was formed in 1787 and managed to recruit several members of Parliament by 1807. Those MPs were led by William Wilberforce and were known as the “Saints”. Many of them viewed the abolition of slavery as a divinely ordained crusade. When the Act was finally brought to Parliament, it was championed in the House of Lords by Lord Grenville and in the Commons by Charles James Fox, who died before it was signed into law. On February 22, 1807, the motion to abolish the Atlantic slave trade was carried in the House of Commons by 283 votes to 16.
Britain then set about pressuring other countries to end their own slave trades. The United States followed suit, abolishing the Atlantic slave trade the same year (though, like Britain, it kept its internal slave trade going). Over the next few years, other nations agreed to end their trade: Portugal in 1810, Sweden in 1813, France and the Netherlands in 1814, and Spain in 1817. The Royal Navy established the West Africa Squadron in 1808 to patrol the coast of West Africa and seize slave ships (they captured around 1600 and freed 150,000 Africans between 1808 and 1860). The Navy declared ships transporting slaves to be the same as pirates, and action was taken against African leaders who continued to play nice with those enslaving their own people. Over 50 African rulers signed anti-slavery treaties.
For many, abolishing the slave trade was not enough, and the campaign continued to press for the abolition of slavery itself. This finally happened with the passage of the Slavery Abolition Act in 1833.