Wilberforce's life took a new turn when he travelled to Nice with the teacher who had stood him on the desk 15 years before, Isaac Milner. He had not realised that Milner believed in the same evangelical religion as his aunt, and in the course of two holidays together, Milner reconverted him.
Right: An American poster for the auction of slaves.
Who were the other major figures in the abolitionist cause? Click here for a who's who of those who fought against slavery.
Wilberforce shut himself away from his friends for months, while he studied the Bible and religious books. He gave up dancing, the theatre and high society parties, and more positively he determined to put his life to better use than he had before.
When he emerged from his cocoon, it was Pitt who suggested a way to do it: to take charge of getting a law passed to ban the slave trade. Some 40,000 slaves were taken from Africa every year by the British alone, crammed into ships like sardines, often with only two feet of headroom, and taken to the Americas. Some protesters had taken a lead such as Granville Sharp and Thomas Clarkson but they needed someone to drive a bill through parliament.
Wilberforce, with the help of other abolitionists, spent two years researching the evils of the trade and helping a government inquiry. The result was a three and a half hour speech to the House of Commons, in 1789, detailing the horrors that had been uncovered and demanding an end to the trade.
MPs agreed it was "one of the ablest and most eloquent speeches that was ever heard in that or any other place." It was backed by the first nationwide petition campaign ever. But there was a powerful slavery lobby in parliament, and the House of Commons decided to have its own two-year inquiry before going any further.