Martin A. Klein is a professor emeritus from the University of Toronto. He has written or edited a dozen books, mostly on slavery and the slave trade in Francophone West Africa. He is the author of Slavery and Colonial Rule in French West Africa, the editor of Breaking the Chains: Slavery, Bondage, and Emancipation in Modern Africa and Asia and coeditor (with Claire C. Robertson) of Women and Slavery in Africa. He has served as president of the African Studies Association and the Canadian Association of African Studies. Stephen J. Rockel is an associate professor at the University of Toronto. Specializing in East Africa, he is interested in labor, slavery, urbanization, and environmental history, as well as empires and conflict. He authored Carriers of Culture: Labor on the Road in Nineteenth-Century East Africa and coedited (with Rick Halpern) Inventing Collateral Damage: Civilian Casualties, War, and Empire. His current projects include histories of slavery in Tanzania and caravan workers across Africa.