The enterprising spirit that was evident throughout the British Empire and that produced the high standard of living in the colonies also led to the horrifying trade in human beings. England became the most important slaving nation during the eighteenth century, establishing trading posts in Gambia and the lower Guinea coast in Africa. From there English merchants transported slaves to the cities and plantations of the Caribbean and mainland colonies. The Caribbean was by far the larger market for slaves, and by the late colonial period about 90 percent of the population there was black. A substantial proportion of the mainland colonies' population was also enslaved: about one in five during the 1770s. From 1761 to 1810 more than three hundred thousand slaves were imported into the colonies. An estimated 12 percent of those brought over by American traders did not survive the voyage. Even so, the slave population...