The abolition (ending) of slavery marked an important moment in world history. In 1800, there were plantations stretching across the Americas. Tens of thousands of enslaved people were taken every year from Africa to the Americas to work these plantations. Their initial capture and journey across the Atlantic posed so many dangers that many died before leaving the boat. Those who survived suffered a life of harsh labor, terrible living conditions and an almost complete lack of rights. Slavery existed elsewhere in the world—particularly in South Asia and the Islamic World. But nowhere was it as extensive or deep-rooted as in the Americas.

Beginning in 1803, slavery and the slave trade were outlawed in many parts of the world. In 1807-1808, both the United States and Britain outlawed the slave trade, making it illegal to bring enslaved people into their territory. They kept slavery legal, however, so people who were already enslaved continued to be enslaved and their descendants were born into slavery. Independent Haiti became the first country in the Americas to abolish slavery in 1804. They were followed by Cuba in 1886, Mexico in 1829, and much of Latin America soon after. The United States would not follow suit until after the Civil War in 1865. Meanwhile, the major European slave-trading powers slowly abolished the trade. The Netherlands did so in 1814, followed by Portugal, Spain and France by 1820.

Enslaved people were still smuggled into the Americas, in particular to Cuba and Brazil. In these places, it remained legal until quite late in the nineteenth century. But the tide had definitely turned, and slavery would be outlawed in many other regions of the world in the years that followed.

Why did abolition just “happen” in the nineteenth century? What shifted in this era that caused some of the biggest slave-owning and slave-trading societies to suddenly become abolitionists? There are at least three important theories to consider.

Theory 1: Free labor and free wages

Perhaps the most dramatic shift toward abolitionism occurred in Britain and parts of English-speaking North America. In the 1790s, Britain had the world’s largest slave-trading industry, but it became the first large country to make the slave trade illegal in 1807. Slavery was abolished throughout the British Empire in 1835, and northern U.S. states and parts of Canada followed quickly. What changed in these regions? One theory is that it was economic. There were emerging middle-class business owners who used paid workers and saw slavery as unfairly competing with their businesses. Their only participation was that they had occasionally invested in slave trading voyages, but profits were dropping in that terrible industry. Instead, they invested in businesses and paid their workers. Also, they hoped to trade in Africa, either to sell finished goods or to buy African resources. They hoped that the end of the slave trade would make business in Africa more stable and profitable.

These business people were often competing for political power with an upper class of land-owning nobles who were likely to have slave plantations. Ending slavery would hurt these political rivals and help level the playing field.

Thus, it can be argued that slavery was abolished only when it made economic sense for some people.

Theory 2: Morality

Philosopher John Stuart Mill, who lived in this period, argued that abolition was not the result of economic reasons. He said it was caused “by the spread of moral convictions.”

These changing ideas might have been related to Enlightenment thinking. The Enlightenment, which began in the late eighteenth century, promoted ideals of individual freedom. These ideals included “free labor,” meaning that people were paid wages for their work rather than enslaved. Enlightenment thinkers debated who was human. This got people talking about the morality of slavery. But, there were limits to this. In general, the new morality did not see enslaved black people as equals.

These Enlightenment ideas were partly a result of new ways to interpret the Bible. Slavery had often been defended through readings of Old Testament texts that seemed to justify enslavement. Some abolitionists were humanists, who believed strongly in the worth of individual humans. They rejected these Biblical texts entirely. Most abolitionist leaders were actually evangelical Christians who found new freedoms to reread these texts. Noting that the gospel called for “goodwill towards all men,” they argued that slavery went against the spirit of Christianity.

Many of these same abolitionists were also business people who stood to benefit economically. However, working-class people also began to support abolition. They were motivated by a belief that the slave trade was evil, and that supporting abolition was the moral and ethical thing to do. They protested slavery by boycotting sugar and rum, two products made largely by enslaved people. They had little reason to boycott two of their favorite products, other than for moral reasons.

Theory 3: The actions of Africans in the Americas and Europe

There is another theory about abolition stating that black Americans and Europeans took actions that led to the end of slavery. Many of these people were formerly enslaved or the descendants of enslaved people.

In Britain, some of the most effective abolitionists were black. One example was Olaudah Equiano, a formerly enslaved man who argued that that slavery conflicted with Christian belief. His book was one of the most powerful abolitionist texts of the day, and he spoke against slavery all across Britain. Another free African, Ottobah Cugoano, also played an important role and called for the abolition of slavery in his autobiography.

Black abolitionists played an even more significant role in France and its empire. During the French Revolution, black Frenchmen and Frenchwomen called for an end to slavery. They included Jeanne Odo, a woman who was born in the vast plantation colony of Saint-Domingue (now called Haiti). Another figure was Jean-Baptiste Belley, a Senegalese man who had been sold into slavery in Saint-Domingue. Odo, Belley, and others tried to get the French constitution to outlaw slavery. The most significant actions took place in the French Caribbean colony of Saint-Domingue. Enslaved people rebelled against the French colonists, fought off the French army, and gained their freedom in 1804. The Haitian Revolution forcibly ended slavery in France’s largest slave colony. France would abolish slavery in all its colonies by 1848.

In Mexico in the 1820s, abolitionism was also led by people of African descent. Abolition was eventually declared for almost all of Mexico in 1829, by Vicente Guerrero, a president of partly African ancestry. The United States, however, wouldn’t abolish slavery nationally for three and a half decades.

Conclusion

Most of the world’s nation-states abolished slavery by the beginning of the twentieth century—barely more than 100 years ago. However, some forms of slavery remained in place (and still remain today). In some places, such as the Islamic World, slavery continued to exist outside the law. In other places, freed people continued to live in conditions similar to slavery. Because of the class systems in South Asia, people were forced to do harsh work with no real escape. In the United States, there were racist systems in place that continued to oppress the formerly enslaved. Many had to work in sharecropping, which was similar to slave labor.