The Slave Trade Act (citation 47 Geo III Sess. 1 c. 36) was an Act of Parliament of the Parliament of the United Kingdom passed on 25 March, 1807, with the long title "An Act for the Abolition of the Slave Trade". The original act is in the Parliamentary Archives. The act abolished the slave trade in the British Empire, but not slavery itself; that had to wait for the Slavery Abolition Act 1833. The British trade in slaves began in 1562, during the reign of Elizabeth I, when John Hawkins led the first slaving expedition.
The Committee for the Abolition of the Slave Trade, which led the campaign that pushed the act through, was a group of Evangelical Protestants allied with Quakers and united in their opposition to slavery and the slave trade. The Quakers had long viewed slavery as immoral, a blight upon humanity. By 1807 the abolitionist groups had a very sizable faction of like-minded members in the United Kingdom Parliament. They controlled at their height 35-40 seats.
Known as the "saints", this alliance was led by William Wilberforce, the most important of the anti-slavetrade campaigners. These parliamentarians had access to the legal draughtsmanship of James Stephen, Wilberforce's brother-in-law, and were extremely dedicated. They often saw their personal battle against slavery as a divinely ordained crusade. In addition, many who were formerly neutral on the slavery question were swayed to the abolitionist side from security concerns after the successful slave revolt leading to the Haitian Revolution in 1804.
Their numbers were magnified by the precarious position of the government under Lord Grenville (his short term as Prime Minister was known as Ministry of All the Talents). Grenville himself led the fight to pass the Bill in the House of Lords, while in the Commons the Bill was led by the Foreign Secretary, Charles James Fox, who died before it was finally signed into law. Not long after the act was passed, Grenville's government lost power to the Duke of Portland. Despite this change, the later British governments continued to support the policy of ending the slave trade.
After the British ended their own slave trade, they pressed other nations to do the same. This reflected both a moral sense that the trade should be stopped everywhere and fear the British colonies would become uncompetitive. The British campaign against the slave trade by other nations was an unprecedented foreign policy effort. The United States abolished its African slave trade at the same time, though it did not attempt to abolish slavery in America.
Both the British and American laws were enacted in March 1807, the British law coming into force on May 1, 1807 and the American on January 1, 1808. Small trading nations that did not have a great deal to give up, such as Sweden, quickly followed suit, as did the Dutch, also by then a minor player. The Royal Navy declared that ships transporting slaves were the same as pirates, and so ships carrying slaves were subject to destruction and any men captured were potentially subject to execution. Enforcement of the US law was less effective, and the US government refused to comply with joint enforcement, partly because of concern over British press gangs.
Between 1808 and 1860, the West Africa Squadron seized approximately 1,600 slave ships and freed 150,000 Africans who were aboard. Action was also taken against African leaders who refused to agree to British treaties to outlaw the trade, for example against "the usurping King of Lagos", deposed in 1851. Anti-slavery treaties were signed with over 50 African rulers.
In the 1860s, David Livingstone's reports of atrocities within the Arab slave trade in Africa stirred up the interest of the British public, reviving the flagging abolitionist movement. The Royal Navy throughout the 1870s attempted to suppress "this abominable Eastern trade", at Zanzibar in particular. In 1890 Britain handed control of the strategically important island of Heligoland in the North Sea to Germany in return for control of Zanzibar to help enforce the ban on slave trading.