In 1760, the ownership of African slaves was common across the Americas, ubiquitous in Atlantic Africa, and tolerated if not always officially permitted in much of Western Europe. By 1820, a new moral critique of colonial slavery and the Atlantic slave had led to the first organised efforts for their abolition. It would seem that the revolutionary era brought with it the beginning of the end for slavery in the Atlantic world. Yet, at the same time, there had never been more slaves in the Americas than there were in 1820. The expansion of the Atlantic slave trade and its increasing concentration on Brazil had profound consequences for the peoples and societies of West Africa. The Age of Revolutions was an era of spectacular growth in the institution of slavery in the Americas, when considered from a hemispheric perspective. This article suggests that the history of warfare has particular relevance to the history of slavery, and, as will become apparent, anti-slavery, in the Atlantic world.