This book examines the gradual decline of slavery in Northern Nigeria during the first forty years of colonial rule. At the time of the British conquest, the Sokoto Caliphate was one of the largest slave societies in modern history. The authors have written a thoughtful and provocative book which raises doubts over the moral legitimacy of both the Sokoto Caliphate and the colonial state. They chart the development of British colonial policy towards resolving the dilemma of slavery and how to end it.