Portuguese Slave Trade
Authors: Caldeira Arlindo 
Published: January 2024

Between 1441 and 1444, Portuguese navigators exploring the west coast of Africa captured the first contingents of Africans on the Mauritanian coast and subsequently shipped them to Portugal. Most of them were Muslim Berbers, but there were also individuals among them from sub-Saharan Africa who had been brought to the Barbary Coast by way of the caravan routes.

These first slave-raiding expeditions fueled a plan to divert one of the trans-Saharan routes to the coast, which the Portuguese successfully accomplished when trade relations with the Berbers became regular. They built a fortified outpost in the Bay of Arguin, in Mauritania, from where several thousand slaves were sent to Europe between 1448 and the early 16th century.

In the meantime, the Portuguese had continued to advance down the coast of Africa and had established commercial relations with the local authorities and merchants in sub-Saharan Africa who were inclined to sell captives, as was the case of the Wolof people in the Senegambia region.

The Portuguese monarchy secured monopoly over the slave trade along the African coast with the promulgation of the Papal Bulls (1452–1456). They gave the Portuguese crown authorization to raid and trade exclusively, unlike other European powers that did not enjoy the same privilege. One of King João II of Portugal’s (1481–1495) projects was to establish several trading posts along the African coast, following the example of the fort of Arguin, intended for the trade of slaves. However, this project proved unsuccessful, whereupon the archipelagos of Cabo Verde and São Tomé and Principe assumed a prominent role as entrepot in the trade between Africa and Europe. When the Spanish king authorized a direct connection between the markets of Africa and Central America from 1518 onward, the Cabo Verde and São Tomé islands became the main suppliers of captive labor for the New World throughout most of the 16th century.

In the early 17th century, the already very vulnerable Portuguese monopoly collapsed, and the other European monarchies began to compete directly with the Portuguese in the transatlantic trade of human beings.

Portuguese slave traders, who had previously preferred the ports between the Senegal River and the Bight of Biafra for captive acquisition during the 17th and 18th centuries, turned their attention to West Central Africa, mainly to what became known as Angola. A bilateral and direct route was established between the port of Luanda (and later, Benguela) and Brazil, to where approximately 10,000 enslaved people were sent every year. After the second half of the 18th century, East African markets also began to supply enslaved Africans to the transatlantic trade.

Whereas in Northern Europe, abolitionist movements had been gaining momentum by the turn of the 19th century, both Portugal and Brazil (which became independent in 1822) resisted ending their involvement on the slave trade. Several laws were promulgated during the early 19th century; however, a total ban on the slave trade was only achieved after a series of laws enacted in Portugal between 1836 and 1842 and in Brazil in 1850. Until then, partial restrictions had little effect, resulting only in an intensification of the very lucrative clandestine slave trade.