In the Cause of Humanity is a major new history of the emergence of the theory and practice of humanitarian intervention during the nineteenth century when the question of whether, when and how the international community should react to violations of humanitarian norms and humanitarian crises first emerged as a key topic of controversy and debate. Fabian Klose investigates the emergence of legal debates on the protection of humanitarian norms by violent means, revealing how military intervention under the banner of humanitarianism became closely intertwined with imperial and colonial projects. Through case studies including the international fight against the slave trade, the military interventions under the banner of humanitarian aid for Christian minorities in the Ottoman Empire, and the intervention of the United States in the Cuban War of Independence, he shows how the idea of humanitarian intervention established itself as a recognized instrument in international politics and international law.