Spain and Portugal signed the Treaty of Tordesillas to divide overseas exploration and colonization into zones of influence. This helped shape who would control Atlantic routes and colonies, including early sites tied to enslaved labor and slave trading. It set a political framework that later supported large-scale forced labor systems in the Americas.
In the early 1500s, Portuguese planters developed sugar production on São Tomé using forced labor, including enslaved Africans. These plantations became an early model for plantation slavery that would later spread to Brazil and the Caribbean. The rising demand for labor-intensive sugar helped push the Atlantic slave trade into a durable economic system.
In 1562–63, John Hawkins led what is often described as the first English slave-trading voyage, taking captive Africans from West Africa and selling them in the Spanish Caribbean. The profits encouraged further English participation in the trade despite Spanish restrictions. This marked a major expansion of the trade beyond Iberian powers.
In 1672, England chartered the Royal African Company, giving it strong state backing for trade on the West African coast. The company became deeply involved in trafficking enslaved Africans to English colonies in the Americas. This helped turn the slave trade into a highly organized, finance-driven business tied to imperial policy.
The Peace of Utrecht reshaped European empires and commercial rights after a major war. As part of this settlement, Britain gained the asiento (contract) to supply enslaved Africans to Spanish colonies, expanding British involvement across imperial boundaries. The asiento also encouraged smuggling and intensified competition around Caribbean trade.
On September 9, 1739, enslaved people in South Carolina launched the Stono Rebellion, attempting to reach Spanish Florida in search of freedom. The revolt alarmed colonial authorities and led to stricter slave laws aimed at limiting movement, assembly, and education. It showed that the trade and plantation slavery system faced continuous resistance from enslaved communities.
In August 1791, a mass uprising of enslaved people began in the French colony of Saint-Domingue, igniting the Haitian Revolution. The conflict disrupted the world’s most profitable sugar colony and shook Atlantic slave societies. It demonstrated that enslaved people could overthrow the plantation system through sustained rebellion and war.
On February 4, 1794, France’s National Convention decreed the abolition of slavery in all French colonies. Although enforcement varied by colony and later reversals occurred, the decree signaled that revolutionary politics could directly challenge Atlantic slavery. It also influenced debates about citizenship and rights for formerly enslaved people.
On March 25, 1807, Britain passed the Slave Trade Act, prohibiting the Atlantic slave trade in the British Empire. The law did not free people already enslaved, but it aimed to stop future trafficking by British ships and merchants. This marked a major shift because Britain had been one of the largest slave-trading powers.
On March 2, 1807, the United States enacted a law to prohibit importing enslaved people, taking effect on January 1, 1808 (the earliest allowed by the U.S. Constitution). The law reduced legal transatlantic imports but did not end slavery or the domestic slave trade. Illegal smuggling continued, showing the gap between law and enforcement.
Beginning in 1808, Britain used naval patrols—known as the West Africa Squadron—to intercept slave ships off West Africa. This shifted suppression from laws on paper to policing at sea, though enforcement was difficult and contested. Over time, the patrols became a central tool in Britain’s international anti-slave-trade campaign.
In 1817, Spain and Great Britain concluded a treaty setting deadlines to abolish the Spanish slave trade, including a full end across Spanish dominions by May 30, 1820. The agreement also restricted Spanish trading north of the equator sooner. These kinds of treaties show how abolition increasingly depended on international diplomacy and enforcement mechanisms.
On November 7, 1831, Brazil formally prohibited the transatlantic importation of enslaved Africans. In practice, trafficking continued on a large scale for years, and the law became known as a measure that existed more “on paper” than in reality. This gap reflected the power of plantation interests and the profits tied to continued forced labor.
On September 4, 1850, Brazil enacted the Eusébio de Queirós Law, strengthening measures to suppress the transatlantic slave trade. British pressure and naval actions contributed to Brazil’s move toward stronger enforcement. While slavery inside Brazil continued until 1888, this law was a key turning point in closing one of the trade’s largest remaining markets.
In 1860, the schooner Clotilda illegally brought captive Africans to Alabama decades after U.S. importation was banned. The voyage shows how demand for coerced labor could sustain trafficking even under prohibition, using secrecy and deception. Survivors later helped found Africatown near Mobile, preserving community memory of the trade’s final U.S. phase.
By 1867, Britain’s West Africa Squadron—active since 1808—was wound down as the transatlantic slave trade had sharply declined and legal bans had spread. Suppression combined changing politics, international treaties, and resistance by enslaved people to weaken the trade over time. The squadron’s end marks a late institutional endpoint for a major state effort to police the Atlantic slave-trading system.
Transatlantic Slave Trade (c. 1500–1867)