Chapter 4 focuses on the struggle against the Atlantic slave trade and the emergence of a humanitarian understanding of intervention. It begins by briefly outlining the system of the transatlantic traffic in slaves, which, by reducing human beings to a mere commodity in a circular trading system, constituted one of history’s worst humanitarian disasters. One of the central concerns of the abolitionists, who towards the end of the eighteenth century grew from a small cohort of well-connected activists to a mass movement, was to reverse this process of dehumanisation and render slaves visible in public discourse as fellow human beings who were suffering and in need of help. The focus is thus placed on the successful humanitarian mobilisation of the public by means of a targeted ‘humanitarian narrative’ and an unprecedented combination of multifarious instruments of appeal. For strategic reasons, the abolitionists concentrated their efforts on the slave trade, which was to be terminated by means of state intervention. A close interlinkage of mobilisation in parliament and civil society can be observed here, for the activists used petitions and legislative initiatives in their attempts to make their cause the official policy of the British government. In doing so, the abolitionists were the first to link humanitarianism with the policy and practice of state intervention.