By the 1480s and into the early 1500s, Portugal used enslaved Africans heavily in Atlantic island colonies off West Africa, creating plantation and trading models later applied in the Americas. These islands became early hubs linking African captivity, maritime transport, and plantation production. The approach helped normalize large-scale, race-based slavery in Atlantic economies.
Around 1500, Spain and Portugal expanded New World colonies as Indigenous populations declined sharply under conquest, disease, and forced labor. Colonists increasingly turned to importing captives from Africa to meet labor demands in mines and plantations. This shift helped lock West and Central African regions into an expanding transatlantic market for forced labor.
In 1517, the Spanish Crown began issuing asientos—contracts that gave private merchants monopoly rights to supply enslaved Africans to Spanish America. This system tied imperial finance to human trafficking and helped scale up forced migration from West and Central Africa to the Americas. It also encouraged foreign merchants (Genoese, Portuguese, later others) to organize Atlantic shipping networks.
In August 1637, the Dutch took Elmina Castle (in present-day Ghana) from Portugal during the Dutch–Portuguese conflict. Control of Elmina strengthened Dutch access to coastal trade routes and fort-based holding systems used to confine captives before shipment. It also shows how European warfare and fort competition on the African coast shaped the slave trade’s logistics.
In 1672, England chartered the Royal African Company, giving it strong state backing in West African commerce and the trafficking of enslaved Africans. Company forts and contracts helped expand English participation and institutionalize the trade through regulated voyages. The company’s activities connected West African coastal markets to Caribbean plantation growth, especially sugar.
In 1698, Parliament opened English trade with Africa beyond the Royal African Company’s monopoly framework. With more merchants able to enter the business, English slaving voyages increased and competition intensified along the West African coast. This policy shift helped drive higher volume trafficking during the 1700s.
In 1713, the Treaty of Utrecht awarded Britain (through the South Sea Company) a major asiento contract to supply enslaved Africans to Spanish America. The agreement set quotas and created new legal pathways for British involvement in Spanish colonial markets, alongside widespread smuggling. It shows how diplomacy and imperial rivalry directly shaped slave-trading privileges and routes.
During the 1700s—especially the 1780s—the transatlantic slave trade reached its highest average annual volumes. Growing sugar and other plantation economies in the Caribbean and the Americas drove sustained demand for forced labor. This peak period intensified violence on the African coast, the Middle Passage, and plantation regimes, while also fueling abolitionist debate.
In 1791, a massive uprising in the French colony of Saint-Domingue began what became the Haitian Revolution. The conflict disrupted one of the world’s most profitable slave-based plantation systems and forced European powers to confront the instability of slavery under war and resistance. Its outcome reshaped Atlantic politics and strengthened abolitionist arguments.
On January 1, 1804, Haiti declared independence, following years of war that began with the 1791 uprising. Haiti’s success demonstrated that enslaved and formerly enslaved people could overthrow a major colonial power and end plantation slavery locally. The new nation faced diplomatic isolation and economic retaliation, but its existence changed abolition debates across the Atlantic world.
On March 25, 1807, the UK passed the Slave Trade Act, prohibiting British participation in the Atlantic slave trade across the British Empire. This did not end slavery itself, but it changed maritime enforcement, diplomacy, and commercial strategy. British abolition became a major external pressure on other slave-trading states and on coastal trading systems in West Africa.
The United States prohibited the importation of enslaved people effective January 1, 1808, limiting legal U.S. participation in the transatlantic trade (though illegal trafficking continued). In the same period, Britain created the West Africa Squadron to patrol West African waters and intercept slave ships. Together, these steps marked a shift from legalization toward international policing—unevenly enforced and often contested.
In 1850, Brazil enacted the Eusébio de Queirós (Queiroz) Law, making the transatlantic slave trade illegal in the Brazilian Empire. British naval pressure and seizures helped force the issue, and the law significantly reduced large-scale arrivals from West Africa soon after. Slavery inside Brazil continued until 1888, but 1850 is a key end-point for the legal Atlantic trade to the largest remaining destination.
Atlantic Slave Trade from West and Central Africa (1500–1850)