From [[Not A Nation of Immigrants]]: > In 1444, the Portuguese were the first Europeans to sail south to West Africa to enslave 240 Africans to sell at the Lisbon slave market, initiating the transatlantic slave trade. The Portuguese monarch Alfonso V made the first slave auction into a spectacle and show of power to other Christian monarchies. A few years later, papal bulls of 1452 and 1455 validated the Portuguese monarchy’s dominion over West Africa and the subjugation of the residents.