This is the first comprehensive history of the British and Foreign Anti-Slavery Society (BFASS), from its founding in 1838. The Society, set up by Quaker Joseph Sturge and Lord Henry Brougham after the abolition of slavery in the Empire, married the campaigning anti-slavery movement with the British mission to civilize the world. The BFASS took up the cause of slavery practiced by other countries, often rivals, like the United States, France, Spain and Portugal, creating a new model of human rights diplomacy. Championing British rule, though often being critical of government policy, put the society into difficult controversies. The BFASS was so hostile to America that it initially welcomed the secession and then later took up the cause of Morant Bay rebels in Jamaica, pressing for Governor Eyres prosecution. With the closing of the Atlantic slave trade the Society turned to East Africa and the Arab slave traders working out of Zanzibar. It was a turn that led the BFASS to lobby for colonial rule in Africa as a remedy to slave-trading, so that the Society helped to prepare for, and publicize the 1890 Brussels Conference that carved up Africa. Allied with the colonial project, the Society was severely tested in its humanitarian goals, by the growing knowledge of atrocities committed against native peoples in the colonies.