The practice of humanitarian intervention – that is to say, of military intervention in the internal affairs of a sovereign state to stop the mass atrocities and the violation of humanitarian norms – is commonly situated within the international politics of the twentieth and twenty-first centuries. Yet recent scholarship has identified the roots of humanitarian intervention in the nineteenth century. In this context, the practice of enforcing the abolition of the slave trade is pivotal, because it established the concept of humanitarian intervention as a recognized instrument in international politics. Cloosely intertwined with imperial and colonial projects, enforcing abolition however shaped also more general legal debates of when and how “civilized” states should intervene in a humanitarian crisis. Insofar these debates went far beyond the sole issue of intervening militarily against the slave trade, but significantly connected and shaped various fields of nineteenth century humanitarianism.