Black slave labor undergirded worldwide capitalist expansion.

Evidence

Black labor became the foundation stone not only of the Southern social structure, but of Northern manufacture and commerce, of the English factory system, of European commerce, of buying and selling on a world-wide scale; new cities were built on the results of black labor, and a new labor problem involving all white labor, arose both in Europe and America, (p. 5) And American slavery would also consist of social relations given their character by the ideology of white racial superiority. — Cedric J. Robinson, Black Marxism_ The Making of the Black…, 932