The slave ship was a strange and potent combination of war machine, mobile prison, and factory. Loaded with cannon and possessed of extraordinary destructive power, the ship’s war-making capacity could be turned against other European vessels, forts, and ports in a traditional war of nations, or it could be turned to and sometimes against non-European vessels and ports in imperial trade or conquest. The slave ship also contained a war within, as the crew battled slaves, the one training its guns on the others, who plotted escape and insurrection. Sailors also “produced” slaves within the ship as factory, doubling their economic value as they moved them from a market on the eastern Atlantic to one on the west and helping to create the labour power that animated a growing world economy in the eighteenth century and after.In producing workers for the plantation, the ship-factory also produced “race.” At the beginning of the voyage, captains hired a motley crew of sailors, who would, on the coast of Africa, become “white men.” At the beginning of the Middle Passage, captains loaded on board the vessel a multiethnic collection of Africans, who would, in the American port, become “black people” or a “negro race.” The voyage thus transformed those who made it.
– Marcus Rediker, The Slave Ship: A Human History (2007)