No nation shipped more enslaved Africans to the Americas than the British during the course of the 18th century. Approximately 2.4 million captives were sent from West Africa on British ships for a life of unending toil in the plantation societies of North America and the Caribbean.


The economic consequences reverberated across the 18th-century British empire. They inspired rapid urban development in port towns such as Liverpool and Bristol, Philadelphia and Boston. They opened new markets for British exports in Africa, the Caribbean, and North America. And they made tobacco and sugar widely available, fostering new rituals of consumption.

The slave trade, all recognised, helped make the Atlantic empire work. For most, the many slave ships that left British ports for Africa each year represented a tribute to British enterprise and the economic liberty of British subjects.

In context: learn more about the transatlantic slave trade

By the spring of 1788, however, the slave trade had begun to acquire rather different associations to most men and women throughout England and Scotland. Quickly, they were coming to regard the slave trade as inhumane, wasteful, horrid, and shameful, rather than as a source of national pride. Petitions to the House of Commons requesting action against the British slave trade poured in from every corner of the country, from Norwich to Falmouth, from Southampton to the Orkney islands.

That rapid shift in public opinion has long attracted the attention of historians, who, for years, tended to emphasise religious and intellectual trends in late 18th-century Britain, or the cultural consequences of economic change in the early Industrial Revolution. But, in recent years, we are learning more about how the rise of popular anti-slavery sentiments depended upon shifting conceptions of national identity, in the question of what it meant to be British.

Anti-slavery opinion circulated in the British Empire many years before the formation of an anti-slavery movement in the 1780s. A spokesman for the Africa traders acknowledged in 1746 that “many are prepossessed against the Trade, thinking it a barbarous, unhuman, unlawful traffic for a Christian Country to trade in Blacks”. But such objections failed to inspire a sustained critique of the slave trade or colonial slavery for much of the 18th century.

Few could see how the nation or its merchants could get along without it. And there was no reason to think that slaveholders could be persuaded to surrender their property in enslaved men and women, or that the British government had either the authority or the ability to take such property from its subjects.

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Shackled Captive
1774: A slave in chains expressing the inhumanity of slavery with the words 'Am I not a man and a brother?'. (Photo by MPI/Getty Images)

The most urgent and pointed protests instead came from the opponents of slavery in the North American and West Indian colonies, who not only despised the cruelty and injustice of slave labour, but feared that it corrupted the morals of colonial society and risked the prospect of bloody insurrections. For most in Britain, however, the horrors of the slave trade and the dangers of slaveholding were out of mind because they were very much out of sight.

Enslaved men and women in London

The growing number of enslaved men and women brought to London after the conclusion of the Seven Years’ War in 1761 gave the problem of slavery new significance to English observers. Did slaves in the colonies remain slaves when taken to England by their owners? Could slavery exist in a society that lacked slave law?

These questions lay at the heart of the consequential case of Somerset v Steuart, adjudicated by Lord Mansfield at the Court of King’s Bench in 1772. Granville Sharp, an advocate for the slave, Somerset, had spent six years trying to prove that slaveholding was illegal in England, that it violated the fundamental tenets of the Common Law. He feared that allowing the colonial slave codes to shape the law of England would make England, as Sharp put it, “as base, wicked, and tyrannical as our colonies”.

Lord Mansfield confined his decision to the specific question that brought the case of Somerset v Steuart to his court: whether the slaveholder James Steuart could ship Somerset out of the kingdom against his will. He found for the plaintiff, declaring that “so high an act of dominion” required an act of Parliament. In doing so, Mansfield evaded the more general question about the legality of slavery in England or in the empire. But, by curtailing the liberties of slaveholders, he made their right to slave ownership unenforceable. More importantly, his verdict encouraged the view that slavery was, in the words of one disappointed Jamaican slaveholder, “repugnant to English laws”.

More than a few of those hostile to the American Revolution concluded that American slavery not only exposed American hypocrisy but also showed a more virtuous England to be the true land of liberty

That interpretation of the Somerset case proved useful to British defenders of the empire in the era of the American Revolution. Lord Mansfield’s decision reassured the English that they lived in a land of liberty. And it conveyed this comforting message just when certain colonists in North America had begun to insist that colonial subordination to a British parliament, almost by definition, meant enslavement to tyrannical authority. “Slavery is no part of our Constitution,” wrote a government spokesman in 1775. “We have no idea of it in our law. It is not to be found in our country. Negroes here, wherever they have been slaves before, are emancipated in a moment by setting foot upon our liberating shores.”

This situation seemed to stand in stark contrast to conditions in the colonies, where slaveholding was nearly ubiquitous, even as the colonists insisted on the sanctity of natural liberty. “Why do we hear the loudest yelps for liberty from the drivers of Negroes?” Samuel Johnson famously asked. More than a few of those hostile to the American Revolution concluded that American slavery not only exposed American hypocrisy but also showed a more virtuous England to be the true land of liberty.

American patriots resisted these conclusions, as might be expected, and, in turn, called attention to British supremacy in the transatlantic slave trade. In the years before the American War of Independence, as if to emphasise the point, the individual colonies attempted to eliminate or curtail the importation of enslaved Africans to North America. There were slaves in the colonies, the American patriots began to insist, because British traders had shipped them there. And there were some like Thomas Jefferson who implied that American slavery might even be abolished if the 13 colonies could manage to free themselves from the British Empire.

This moral posturing on both sides of the Atlantic did not entail, necessarily, a particular concern with the fate of enslaved Africans. The combatants often cared more about embarrassing each other than addressing the problem of slavery. But drawing attention to slavery in this way prompted a radical shift in moral perception. By describing an investment in slavery as proof of collective vice, they helped define opposition to slavery as proof of collective virtue.

Conflict with the colonies

Most in Britain resisted the suggestion that American slavery was also a British problem, at least at first. Those sympathetic to the American Revolution, of course, sometimes echoed patriot propaganda. “It is not the fault of the colonies”, Welsh philosopher Richard Price wrote in 1776, “that they have slaves among them”. Most, however, continued to think of overseas enterprise as a progenitor of wealth and liberty during the 1770s. And when reservations did arise about the ethics of imperial expansion, most British commentators worried less about what the British did in the empire than what empire did to Britain.

All of this began to change, however, with the end of the American war. Defeat inspired a searching examination of British conduct around the globe. Granville Sharp had long thought the American rebellion represented divine punishment for the toleration of slavery on both sides of the Atlantic. Some came to agree with him in the years that followed. “We shall never prosper as a nation,” concluded Reverend Gilbert Wakefield in 1783, “until that execrable traffic be abolished”.

From the wreckage of the American War of Independence came the first sustained concerns with the moral image of the British Empire. There emerged in this era the concept of trusteeship, the idea that rule should be exercised “for the benefit of the governed”, as Edmund Burke put it in 1783, as well as the governors.

“That where Britain’s power/Is Felt,” poet William Cowper wrote two years later, “mankind may feel her mercy too”. Evangelicals within the Church of England looked for ways to promote the Christian conversion of slaves in the British West Indies. Returned military officers urged the British government to provide for the thousands of escaped American slaves who assisted the British army during the War of Independence.

This new interest in charity to Africans gave an opening to Quakers in Britain, who disliked the slave trade but had been reluctant to push for its abolition. In 1783 they petitioned the House of Commons for an end to Britain’s slave trade and followed it with a propaganda campaign to mobilise public opinion.

The Society for Effecting the Abolition of Slave Trade crystallised these impulses. Its establishment in 1787 indicated the growing confidence of the formerly disparate campaigners, an unusual amalgam of Quakers, Evangelicals such as William Wilberforce and Hannah More, and Anglican churchmen, most notably Thomas Clarkson.

That confidence was inspired by the conviction that the British public had come to regard the slave trade as a national embarrassment, and from the belief that many men and women in Britain wished to see their nation on the side of liberty and virtue. If those desires could be galvanised into a political movement, then it might be possible to force Parliament to do what it otherwise would not – curtail a crucial branch of British commerce for the sake of justice and the moral reputation of the nation.

The move towards abolition

From the first, the new abolition society aimed to inspire an outpouring of petitions against the slave trade. More than one hundred had arrived at the House of Commons by the close of the 1788 parliamentary session. Reverend Robert Boucher Nickolls hoped abolition would show the new United States “that we are no less friendly to liberty than they”. “Nothing in my whole experience”, one activist confessed privately, “has given me more reason to think well of my country”.

By 1792, slave trade abolition had become the cause of a nation. Perhaps half a million men and women across the country refused to consume West Indian sugar in order to show their hostility to the slave trade and slave labour. The petition campaign of 1792 dwarfed the already impressive petition drive of 1788. In a matter of weeks, 519 petitions bearing approximately 400,000 signatures arrived at the House of Commons. On the side of the slave trade there were four. If public opinion could have decided the question, the British slave trade would have been abolished in 1792.

But many MPs continued to fear that abolition of the slave trade would lead also to a sacrifice of imperial wealth and power. And not all believed the abolitionists who argued that abolition would force West Indian planters to treat their slaves better, or that a trade in African staple crops might take the place of the trade in slaves. The House of Commons resolved in 1792 to abolish the slave trade, but gradually, in 1796. This, still, was too much for the House of Lords, which refused its assent and asked for more time to study the issue.

The revolutions in France and in St Domingue in the 1790s that brought down a political order and then destroyed the most productive plantation economy in the Americas brought the British anti-slavery movement to a near halt for more than a decade. The declaration of war against France in 1793 led to the suppression of internal dissent, a crackdown that severely inhibited anti-slavery politics. The British government tried to restore slavery in St Domingue rather than supporting its overthrow. Forty-five thousand British soldiers died between 1793 and 1801 in the effort to suppress the slave insurrection in St Domingue and defend the British sugar colonies.

At the close of the 18th century, sustaining the plantation economy remained a strategic and economic priority. And yet anti-slavery also had established itself as the cause of morality, justice, and humanity within the British Isles, and, for a time, had become a source of national pride. A shift in the political and economic circumstances would allow those impulses to claim centre stage again.

The anti-abolition campaign: how slavery’s few supporters wielded great influence

The defenders of the Atlantic slave trade, with few exceptions, possessed an economic stake in its success. Otherwise, the slave trading interest enjoyed little public support. This meant that abolitionist petitions routinely dwarfed the number in favour of the slave trade.

At the same time, though, as a vested economic and political interest with close ties to important decision-makers within Parliament, the slave traders and their allies exercised more influence than their comparatively small numbers would at first suggest.

The principal defenders of the trade hailed from the major slaving ports in England – London, Bristol and Liverpool. A few prominent merchants in the trade held seats in the House of Commons. Several other Members of Parliament represented constituencies responsive to the needs of slave trading merchants. The slave traders benefited too from the assistance of the much larger and more influential West India lobby, which viewed abolition as a threat to the sugar business, in both the Caribbean and in England.

With rare exceptions, the trade’s defenders staked their case on the importance of slavery to imperial wealth and power. Rarely did they defend it as a matter of religious or moral principle.

The key steps towards abolition


Somerset v Steuart, June, 1772

Lord Mansfield’s verdict proscribing the powers of owners who hold slaves in England is popularly interpreted as abolishing slavery in England.


British Quakers petition Parliament, June 1783

Urged on by their religious brethren in Philadelphia, the Society of Friends in England presents Parliament with the first petition for slave trade abolition.


The abolitionists organise, May 1787

A committee of 12, led by Thomas Clarkson, establishes the Society for Effecting the Abolition of the Slave Trade, the first non-denominational anti-slavery organisation in the British Isles.


The Dolben Bill, June 1788

The first parliamentary inquiries into the British slave trade conclude with legislation limiting, according to ship’s tonnage, the number of slaves it could carry and requiring the presence of a doctor on each voyage.


Olaudah Equiano’s narrative, March 1789

The former slave Olaudah Equiano publishes an account of his life story, detailing the horrors of enslavement in Africa and the experience of captivity in the Americas.


Slave insurrection in St Domingue, August 1791

The armed uprising of enslaved men and women in the most valuable sugar colony in the Caribbean indicates both the risks of large slave imports and the unpredictable consequences of radical reform.


Popular mobilisation, spring 1792

Anti-slavery organisers mobilise 519 petitions to the House of Commons calling for abolition. In this same period, the boycott of slave-grown sugar reaches its apogee.


Resolution in the Commons, April 1792

The House of Commons authorises the gradual abolition of the British slave trade, and sets 1796 as the terminal date, but the House of Lords refuses its assent.

Professor Christopher Leslie Brown teaches in the Department of History at Columbia University in New York City. His 2006 book Moral Capital: Foundations of British Abolitionism received the Morris D Forkosch Prize for the best book in British and British Imperial History from the American Historical Association


This content first appeared in the March 2007 issue of BBC History Magazine