Thomas Clarkson began his lifelong crusade against slavery and the slave-trade shortly after receiving his B.A. from St. John's College, Cambridge, in 1783. In 1784 and 1785, he won the members' prizes for Latin essays at Cambridge, and his winning essay of 1785 was published the following year as An essay on the slavery and commerce of the human species, particularly the African (J. Phillips: London, 1786). In the course of locating a publisher for this essay, Clarkson formed working relationships with several of the most important emerging figures of the anti-slavery movements in Britain, including James Phillips, Granville Sharp, and William Dillwyn, and Clarkson is credited with bringing M.P. William Wilberforce into the movement at the formation of the Quaker-influenced Committee for Abolition (1787). The continued efforts of the Committee to lobby Parliament and raise the consciousness of the British people to the cruelties of the slave trade resulted, in 1788, in the introduction of legislation before Parliament to curb the harshest forms of treatment, though it was not until 1807 that a bill to end the slave trade managed to pass both houses.
Responding to the egalitarian rhetoric of the French Revolution, Clarkson traveled in Paris in August, 1789, to agitate for anti-slavery legislation before the Assemblé Nationale. While he was moderately successful at attracting political allies, including Lafayette and Brissot de Warville, no legislative action resulted. As part of his efforts, in December, 1789, and January, 1790, Clarkson wrote a series of 13 long, informational letters to the poet Mirabeau, then at the peak of his political influence, to "bring the entire facts of the case [for abolition] before him" (DNB). These letters were never published in French, however, when Clarkson returned to England in February, 1790, they were translated, much compressed and published as Letters on the slave-trade, and the state of the natives in those parts of Africa, which are contiguous to Fort St. Louis and Goree (James Phillips: London, 1791).