Text of a paper presented by evangelical Louis Ruffet at a number of conferences in Switzerland in the late 1880s. Ruffet uses the travel writings of nineteenth-century European explorers of East and Central Africa like Nachtigal, Rohlfs, Trémaux, Stanley and Wissmann, to prove that the slave trade still existed in Africa. He recommends a coordinated European military intervention as an effective means of ending this trade, describing this as a 'humanitarian' use of force: "there is such as thing as legitimate combat, there is a justifiable war" (31). Ruffet pays particular hommage to the central figures in the international anti-slavery "crusade of mercy" (6), Cardinal Lavigerie and King Leopold II of Belgium.