The document that abolished the transatlantic slave trade in the British Empire in 1807 was the Abolition of the Slave Trade Act. This act made it illegal to engage in the slave trade within the empire, though it did not immediately free those already enslaved. The movement to abolish the trade was championed by abolitionists like William Wilberforce, who highlighted the moral and ethical issues surrounding slavery. The act resulted from growing public sentiment against the inhumanity of the slave trade and marked a crucial step toward the eventual emancipation of slaves in British territories with the Slavery Abolition Act of 1833.