Featured Webinar

The Royal Navy’s Campaign Against the Slave Trade

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History Reclaimed was delighted to welcome Professor Andrew Lambert who is the Laughton professor of Naval History at King’s College London and the director of the Laughton Naval unit. He delivered a fascinating lecture on the Royal Navy’s struggles against the slave trade.


Welcome, Ladies and Gentlemen. I can see that there are people who are presently tuning in or signing on or whatever it is that one does with Zoom. And so I’m going to give you a few minutes for that to happen and then I’m going to introduce our speaker today, and then we shall get underway. Getting underway is I think the appropriate metaphor for today’s lecture. This is the second in the series of History Reclaimed webinars on Britain’s struggle against the slave trade. And it’s a great pleasure and an honour to welcome Professor Andrew Lambert today who is the Laughton professor of Naval History at King’s College London and the director of the Laughton Naval unit. He’s the author of prize-winning books. In 2014 he won the Anderson Medal for The Challenge: Britain against America in the naval war of 1812 and one of his most recent works is the, if I may say so, the extremely ambitious and original work Sea Power States meaningly subtitled Maritime Culture Continental Empires and the Conflict that made the Modern World because as those of you who have read the book will know, much of it is about the creation of a maritime culture which is the foundation of the power of Sea Power States. And today we’re very glad to welcome Professor Lambert who is going to talk about the Royal Navy’s struggles against the slave trade, so Andrew over to you.

Thank you very much Robert. Ladies and Gentlemen, it is a great privilege to be here and to have a captive audience, that’s a metaphor I won’t use again, for a discussion of one of the Royal Navy’s longest running and most difficult campaigns, as you all know. I’ll share my screen now.

In 1807, Britain rendered the Atlantic slave trade illegal at a time when the Battle of Trafalgar and the ongoing war against Napoleon meant there were very few ships traveling across the Atlantic that were not British or working in Britain’s interests. It then tasked the Royal Navy with enforcing that law against the very small number of British ships that attempted to continue carrying slaves on the transatlantic route. There were very few law breakers because most British ship owners at that time could find perfectly legitimate and relatively profitable business in what was a booming Atlantic economy. The end of the Napoleonic conflict in 1814 and its slight repeat in 1815 complicated and changed the picture quite dramatically, as former enemy and occupied countries rushed to regenerate their merchant shipping and their colonial holdings and the colonial trades that supported them. The British could see problems emerging. They used the peace process to press the Europeans to follow their lead in abolishing the slave trade. But Spain Portugal and France all refused for a variety of reasons, most of which were concerned with recovering and restoring their devastated tropical colonies to profit, and also to conciliate the colonial elites who were then either attempting or thinking about rebellion. These countries also were concerned that the mechanism for abolishing the trade would be the Royal Navy stopping and searching merchant ships flying their flag, which they saw as an infringement of their sovereignty and a continuation of the Royal Navy’s highly successful economic warfare practices against Napoleon and his allies, but also against the United States in the War of 1812. This practice had been raised as an issue by the French and the Americans in the attempt to make peace at the end of 1814, but the British had insisted that they would not discuss this issue: the right to stop and search merchant ships in wartime on the open ocean was a red line for the British, and it was not considered at the Congress of Vienna or the Treaty of Ghent. This certainly wrangled with the French and the Americans who would very much like to have restrained Britain’s maritime economic power. And this is a theme you’ll find across the long 19th century, and well into the 20th, of Continental military powers anxious to stop Britain using the sea as a strategic means of applying pressure against their weakest element, which is usually their economy.

Having seen their economies devastated by British naval blockades the French the Americans and others had no desire to see this practice extended in peacetime. Consequently, the Atlantic slave trade expanded after 1815 and one of its vehicles was the transition from privateer warfare by the Americans and the French to the use of privateer vessels, and often crews, switching into this different form of illegal activity.

The Atlantic slave trade in the 18th century been conducted by relatively standard merchant ships, overloaded with human cargo, but relatively standard ships. After 1815 most of the ships used in the trade were fast, usually American-built schooners and here we see the Pride of Baltimore in the coloured image, a ship designed for very high speed but relatively limited cargo carrying capacity. This means that the number of slaves that can be stowed on board is limited, but this is the only kind of vessel that will be effective in operating in the Atlantic if the British are able to impose their rules. So we have unemployed privateers, unemployed privateering craft, we have a range of Wars going on in the Caribbean at this stage, from 1815 through to the late 1820s. Wars of independence and liberation by a succession of former Spanish provinces and of course Brazil, all of which have differing policies on the slave trade and slave economies. So a lot of people are moving into this business at the end of conflict in much the same way that piracy had surged at the end of the war of the Spanish Succession (in 1713).

What does the British policy actually look like? Well it is 10, 15 or slightly more, small vessels operating on the northern half of the African Coast, that is north of the Equator, trying to limit the movement of human cargo. The issue for the British is relatively simple. They’ve agreed to outlaw this trade, they wish to uphold the law and British politicians and statesmen are committed to that programme. Across the next 50 years British warships will capture approximately 1,600 slave ships, and they will do so at the cost of more than 2,000 casualties, almost entirely fatal, and almost all casualties of local tropical diseases. This was not an easy campaign, and it was not cost free. In the Royal Navy of the early 19th century, you were more likely to die in the West African anti-slavery Patrol and in any other deployment.

The cost of this long campaign would create domestic opposition as well as international, and one of the things I want to highlight is how the Liberal Party was split down the middle about what to do with the anti-slavery patrol. In 1833 Britain abolished slavery in the British Empire and that reduced the possibility of further demand from the British side but of course in the Caribbean and North America there are many places where slaves are in very large demand following the growth of plantation economies producing goods like sugar and coffee which demand huge amounts of labour. So, these powers, including the American Southern States and Brazil saw the slave trade as essential to their economic well-being: they were not persuaded by the moral case that Britain was making.

The problem for Britain was to find a mechanism by which it could end the slave trade without causing a major war with other major powers, so while there was an ideal at the bottom of all of this, there were much more complex issues involved in persuading rather than coercing great powers like France and the United States to stop trading. The Americans made the Atlantic slave trade illegal in 1807 at shortly after the British, but because of the sectional interests of the American South this law was never upheld and it remained something of a joke right down to the American Civil War, slave trading was put on the statute book as akin to piracy with a penalty of death for those who were captured conducting it, but only one man was ever hung as a slave trader in the United States, and that was in the middle of the American Civil War. The Americans were not capable of suppressing the trade because of the sectional pressures within the pre-civil war United States; the French were not willing to give up the trade for very obvious reasons, which include their possession of Martinique and Guadalupe which had large agricultural economies. Spain and Portugal, the other major European trading powers, were somewhat easier to put pressure on because they were no longer great powers, and Portugal in particular was dependent on Britain for security. but this was a constant balance: the ability to suppress the slave trade depended on Britain’s relations with other major powers, how far would other major powers allow the British to stop ships that were flying their flag, legitimately or otherwise, on the high seas, search them and inspect their papers. The Americans invariably refuse to allow this, and so for much of a period do the French

There’s a great deal of drama in the abolition of the slave trade and here we see the ship Black Joke capturing the Spanish-owned, but almost certainly American-built, slaver El Almirante. The Black Joke was a former slave ship which had been captured. The Royal Navy discovered that its own standard cruisers were not fast enough to capture slave trading vessels. There were dramatic incidents, celebrated in this case in a public print, which reminded people of the cost of the activity. But it was not being brought to a successful conclusion. The wars of the 1820s particularly in the Americas compromised Britain’s ability to operate there. All the states that resisted British pressure did so for powerful, if not necessarily morally valid, reasons. They had very interesting agendas.

The Americans protested that while ships were flying the Stars and Stripes, they were not actually American ships. And it turns out almost all of them were actually built in America, all the best slave carrying schooners were American-built, mostly in Baltimore. These ships would carry multiple papers, they would carry at least one person who could claim to be a citizen of a country other than the United States, normally Portugal or Spain, but most of the crew would have been American, particularly in the early years of the trade. The Americans finally set up their anti-slavery Patrol in 1842, but it was not intended to be effective, the United States Navy was generally controlled by politicians from the American South, most of whom were slave owners and had a vested interest in it not working. It was there to stop the British interfering. The men who made a difference here other than those who served on the patrol and many of them were committed abolitionists were the foreign secretaries of the period, particularly Henry John Temple third Viscount Palmerston, Foreign Secretary in the 1830s and the second half of the 1840s. and then Prime Minister in the late 1850s and into the middle of the 1860s. Palmerston was a lifelong abolitionist. He was absolutely committed to this cause, it was one of the two things he thought most important in what was a very long and very impressive political career, and he was prepared to use pressure diplomatic and Naval to persuade the weaker countries in this trade to break with this process.

The diplomatic and legal complexities of running the patrol were very serious, turning a noble gesture into concrete fact involved hard work: gathering intelligence, processing through courts and building relationships. Many of these slave ships were condemned in prize courts in which British and Portuguese, Spanish or Brazilian judges sat together. It was necessary not just to convince a British judge that this was a slave ship, you had to convince the judge coming from the country where the ship was nominally registered. And that put an enormous pressure on the process. Gathering intelligence, capturing the ship’s papers, these were really important. The due process of law as we would understand that today, had to be followed.

So, for 50 years this trade would continue. But why was there such a large trade? This was not a trade that exists for its own sake. It is demand-led. The millions of enslaved peoples who were shipped across the Atlantic were shipped because there was a market that was ready to pay a premium for them. There was also a large supply on the coast of West Africa. Remember that the slave trade out of West Africa was endemic and had been active long before the Europeans began trading across the Atlantic. Trading in African enslaved people to North Africa had been a commonplace since the ancient world. There were slave markets in Morocco, Algiers and Egypt and there were more slaves traded across the Sahara than were traded across the Atlantic.

So, the first thing that had to be done to deal with a trade like this was to remove demand, and at the same time limit supply. All you can do at sea is limit the trade and if you want a modern analogy you can look at Western attempts to suppress the cocaine trade in the Caribbean. There is a large demand, there is a massive supply, and people can make a lot of money in this business. For all its moral repugnance this is an economic activity. So here are the areas where the majority of enslaved peoples are being traded. One of the issues to remember is that the bottom half of that map is off-limits for the British until 1840s, so the Patrol is only dealing with the West African half of this trade at that point. There is a large market because many of those West Africans regions and states have a long history of sustaining the trade. The sheer numbers involved are striking. The Angola Coast: five and a half million embarked, nearly five million disembarked. Around 12% losses en-route, and we see other trades, even larger. There are some very large numbers involved here: 12.5 million people in this period. The Royal Navy’s patrol was never going to stop that trade, there were never going to be enough ships. The whole Royal Navy would have found it difficult to stop this trade.

A critical problem for those addressing the problem of the slave trade is health. This is extremely unhealthy territory. Malaria and Yellow Fever are endemic on the west coast of Africa. They are spread by mosquito as we all know, but they did not know this. Some captains worked out that it was unwise to be near the coast when the sun set and the mosquitoes came out, but they worked it out by guesswork and experience. Casualties were high, it is difficult to operate close in shore, so the patrol is basically waiting for slave ships to put to sea and then having to try and catch them. A very difficult situation. The attempt to deal with demand begins in the late 1830s under Palmerston’s Foreign Secretaryship. The state of the patrol at that stage is relatively weak, it had unsuitable vessels and it was not stopping very many slavers. The British have no legal authority to search ships carrying slaves between the Portuguese colony of Angola and the various Portuguese stations on the Congo coast into a strong Brazilian market. It was also necessary for the ships, if they were to be lawfully condemned, to actually have slaves on board. You can’t stop a ship that is heading to load with slaves. The British solved this by introducing the “Equipment Clause”. If you stop a ship and it has all the equipment to carry slaves, and that would be manacles, large cooking pots and large stowage of water, you can then condemn it on the basis that is equipped for the trade, even if there are no enslaved people on board. This clause was placed in a treaty with Spain in 1835, and it was critical to moving the trade off the Spanish flag, towards the Portuguese flag. Portugal was reluctant to accept the clause, but the British were willing to bully Portugal in ways they wouldn’t even with the Spanish, let alone the Americans: they insisted. Portugal’s security and its economic prosperity in the 19th century depended very much on its relationship with Britain, and the British had always been prepared to engage very forcefully in the defence of Portugal against external powers. The Tagus River was the centre of Britain’s Atlantic strategic control all the way through the Napoleonic Wars. Those of you who think that the British sent an army to Portugal to drive the French out of Spain have missed the point. The Army was sent to keep the French out of Lisbon and the Tagus. Anything beyond that was a bonus.

Portugal could be bullied and by 1839, Portugal’s slave trade was being degraded and the Portuguese were not in a position to complain. What these measures did was persuade the British that they’re going to have to do something, and you can see here the Portuguese numbers are very high in the period that we’re looking at. Portugal is the largest by flag trading nation in the slave trade from 1807 through to the end of the Atlantic business. We’re looking at very large flows out of West Africa heading into Brazil we’re looking at similarly scaled flows going into the Caribbean and quite clearly into the United States. The United States slave economy is not regenerating, it is being fed from the Atlantic trade. The myth that there are no slaves imported into America in this period is entirely without foundation. Many slaves are being imported, often through third party action coming out places like Cuba. So the United States and Cuba and Brazil are critical and what the British are going to have to do to break the trade is to break that dependence and to impress upon the authorities in those countries just how important this is.

The leader of the anti-slavery patrol in around 1840 is Captain Joseph Denman one of the most prominent abolitionists, and a very effective campaigner for the abolition movement. He runs a much better blockade than some of his predecessors. By 1840 Spanish, Portuguese and Brazilian ships can be searched anywhere in the Atlantic and the equipment clause does apply to them. Better ships have been sent including some of the Royal Navy’s early steamships. The steamship gave a huge advantage because you it could chase fast slave carrying schooners into the wind and overhaul them without any trouble at all. But this was a costly investment, you need not just more ships, more expensive machinery, you also need a large supply of coal and like everything else that is in short supply. Denman demonstrated his zeal by landing at one of the slave stations at Gallinas and he destroyed the factory where the slaves were collected and sold. This led to a long-running legal action where the owners of the slaves and of the station complained that he had violated international law. The case ran on for six years. but it was ultimately decided in Denman’s favour in 1848, and this was a major blow to the West African trade. British courts had upheld the right of the Royal Navy to go ashore and destroy slaving facilities.

Foreign Secretary 1841-46 Lord Aberdeen was more conservative in his attitudes, and he ended coastal raids like the one that Denman had conducted, because he was not sure they were legal, it turns out they were, but he was quick to place the anti-slave trade effort in context. He didn’t want to alienate the Portuguese, but he was keen to put more pressure on Portugal. By 1842 Portugal had conceded the equipment clause and that means the Portuguese are no longer the primary carriers of slaves in the trade between Africa and Brazil. These are now Brazilian-flagged vessels. This shifts the target; Brazil is much more exposed to British pressure than Portugal.

Destroying the Brazilian trade would be a critical blow. Remember that Brazil at this stage was not a republic, it is an Empire, run by an Emperor (Pedro II), and it has an aristocracy. It also has a large planter class. By 1845 there are 21 British warships on the African Coast, including faster sailing ships and seven steam vessels. So the possibilities of trade are being reduced. The Brazilian trade is also moving into the steam age. We tend to think of this as a sailing ship trade, right at the end it will be British naval steamships chasing Brazilian slaving steamships.

Palmerston returned to office as Foreign Secretary in 1846. Now began the most serious attack on the anti-slavery patrol of them all. This doesn’t come from the United States or Brazil, Portugal, Spain or France, it comes from the radical wing of the Liberal Party. The Anti-Corn Law League, led by Richard Cobden and John Bright, protest that paying extra for sugar that was grown by free labour rather than by slaves was disadvantageous to the working classes, and that the cost of the anti-slavery patrol was extortionate and was unnecessary. They put a motion into the House of Commons to stop doing both things, basically to buy the cheapest sugar and to stop paying for a patrol against the Atlantic slave trade. Lord John Russell’s government made this a vote of confidence on the slave trade patrol and both Russell and Palmerston spoke powerfully in support of the cause, to which both of them were committed: they won that vote of confidence. They did not win the economic vote on buying cheap sugar from Brazil and Cuba, where it was grown by slaves. The interest of cheap food trumped morality.

Palmerston’s returned to office in 1846 increased the pressure introducing more effective ships onto the patrol and the decision taken in 1849 to transform the anti-slavery patrol from West Africa to the coast of Brazil. Royal Navy vessels which had been operating in in the River Plate in a war between Uruguay, Paraguay and Argentina were released by the making of peace, and the British Minister in Brazil then switched them to conducting a very active campaign against slave ships in Brazilian coastal waters and harbours. So, the end of the anti-slavery patrol began to in the South Atlantic with British warships inside Brazilian harbours, capturing and destroying Brazilian-flagged slave ships under the guns of Brazilian forts. On one occasion a Brazilian fort fired back, but the British captain ignored it, towed out the Brazilian ships and destroyed them. Brazil was now in a very difficult position. It could either defy the British and go to war, or it could recognise reality. In this case the Brazilians backed down. They then declared that the slave trade was in the hands not of native Brazilians, but of the Portuguese, and of course Brazil was very keen not to be part of Portugal, so this defamatory statement saw slave traders excluded not for their immorality but for their nationality.

Portugal was already out of the trade, now Brazil would follow. When the Brazilians made these concessions, the British pulled back their blockade and relaxed their efforts, very quickly Brazil ceased importing slaves and the slave trade becomes illegal in Brazil. This was a critical movement because it closed one of the two great markets, Attention now switches back to northern demand, and here the complexity was the island of Cuba. This is a classic slave trade image a Royal Navy warship with all sails set chasing a slave schooner, which is doing the same thing. Here is the coast of Brazil this is where the slave trade was mostly operating, and it was the ability of the British to stop that trade, particularly in the southernmost port that of Paranagua, the key slave importing station that would be so important in resolving that.

The trade declined in the South, and was now increasingly focused on Cuba, which had links to the United States. Cuba was the last remnant of Spain’s Empire in the Caribbean. It was largely run by the Queen dowager who is the regent for the young Spanish Queen. She has extensive economic interests in Cuba. Cuban wealth and Cuban trade was the basis of the regeneration of the post-Napoleonic Spanish economy. Much of the trade with Cuba is handled out of Barcelona and is closely connected with the Catalan region, as well as the Spanish South. For the Spanish Cuba is the last vestige of Empire, it’s also the last hope of recovering Empire and any attempt to in to force them to abandon plantation slavery in Cuba would have met with significant resistance. The British weren’t willing to do this because a hostile Spain would have complicated their European diplomacy and perhaps opened Spain to the influence of France. The Franco-British rivalry for influence in Spain in the 1830s and 40s was highly significant in the wider pattern of British international relations, the ‘Spanish Marriages’ crisis of 1846 being classic case in point.

What the British did was further complicated by the position of the United States. In the mid-1840s, as you all know, the United States launched a war of aggression against the Mexican Republic in which it seized large parts of what is now the southwestern United States: California, Texas, New Mexico… The United States also began supporting, if only covertly, filibustering expeditions to try and take over parts of Central America and bring them into the United States. These campaigns were run from the South, many of them out of New Orleans, their purpose was to maintain a favourable balance in Congress between slave owning States and non-slave owning states. This is of course part of the build-up to the American Civil War. The biggest and most attractive target for these filibustering Expeditions was Cuba. So, in the late 1840s the Royal Navy found itself trying to stop slaves being imported into Cuba, but it couldn’t be too zealous on this issue, because it would lose the support of Spain. At the same time, it needed to patrol Cuban waters to prevent the Americans launching an invasion, legally from the government, or illegally through filibustering. Cuba was the key to the entire West Indies: Havana is the most important harbour in the entire Caribbean region and an American fleet based in Havana would close the Caribbean to the British, and indeed everybody else. This was a really important issue for the British going forward.

Havana you see right in the middle on the North coast of Cuba and the passage between Florida and Cuba is critical, and then a very short distance to the Yucatan Peninsula and you’re into the Gulf of Mexico with Jamaica just down to the South. Strategically it was very important to keep Cuba out of American hands, very important to try and stop the slave trade too, but the two things are intention and not in harmony. One of the ironic results of all of this is the British send a ship to patrol Cuban Waters, ostensibly to look for slave carrying vessels. This is the ship HMS Trincomalee, and if you live in the north of England, it’s quite easy to go and visit the Trincomalee which is preserved in Hartlepool, looking pretty much like this. Trincomalee was sent, not to look for slave ships, because it is a relatively slow ship, it is sent to warn off the Americans. Its purpose is not anti-slavery, that’s the cover story, the real story is to provide British power on the spot, deterring the Americans from launching an invasion of Cuba. So again, it’s about graduated and modulated expressions of interest. The commander-in-chief in the Caribbean at this point is a very famous naval officer who most know as Lord Cochrane, the tenth Earl of Dundonald, by now a veteran but one of the heroic figures of the Napoleonic Wars. He’s been sent out there to make sure that nobody misunderstands Britain’s willingness to fight. He is a combative and highly aggressive officer and by sending him out there the British are saying “we have the ships, and we have an admiral who is ready to deal with this problem”.

The British response to the Americans is always modulated by the realisation that, and this is something Palmerston stresses, that in the event of conflict between Britain and the United States, the British will have a major advantage over the Americans. In the War of 1812, the British had used slave rebellion as a key part of their strategy to defeat the United States. The invasion and capture of Washington DC in 1814 was entirely set up by raiding operations in Maryland and Virginia and the encouragement of enslaved people to run away and acquire their freedom by joining the resistance movement. The British set up bases to which they could go, and all of those formerly enslaved peoples were given their freedom as soon as they joined the British. The African American populations of Trinidad and Halifax, Nova Scotia are descended from those people. They were not sent back to America, despite the Americans demanding them back as property the British treated them as free people and offered them refuge within the wider Empire. Palmerston was convinced that if the Americans picked a fight with the British the first thing he would do would be to send British troops many of them of African or West Indian origin into the American South to raise a slave revolt. So, this was the weak point of the United States, something Palmerston was acutely aware of and very willing to think about. In the mid-1850s, he said that if the Americans picked a fight with the British now, they would find they would have less styles on their flag because the southern states would be overrun by British troops and slave rebellion.

The British have controlled Spain into minimising its slave trading but they are not prepared to strong arm Spain into stopping the slave trade, because they fear that Cuba would break away from Spanish control, weakening Spain and reinforcing the United States. So again, this is a question of what is possible as well as what is desirable.

The British were still unable to stop American flag ships carrying slaves across the Atlantic. It was illegal for the British to stop an American registered ship on the high seas and check its papers. As a result, they were obliged to resort to other methods. In 1851 the British destroyed the slave station at Lagos which was the largest on the West African coast. In a major landing operation, the Royal Navy and Royal Marines captured and destroyed the base of a large slaving empire. In 1861 the British annexed Lagos and began the creation of what would become the colony of Nigeria. This was about extending legitimate trade, suppressing illegal trade and finding opportunities to build new relations with local players. As medical knowledge improved it is possible to operate in this area. 1861 would see the end of the Atlantic slave trade, because the last remaining market was destroyed by the outbreak of the American Civil War. As soon as the two halves of the United States have split and the Union had established a blockade of the Confederacy, there was no possibility of trading slaves across the Atlantic into the United States, so the market disappears. By 1865 there are very few ships attempting to make this voyage. In 1866 the commander of the West African anti-slavery patrol reported he had no intelligence of any attempt to do this at all. So, removing the demand was the ultimate cause that ended the anti-slavery patrol. With no demand the Royal Navy was free to switch its attention from the West African slave trade to the East African slave trade. That is another story, but the Royal Navy would be involved dealing with that trade out of the ports of East Africa into the Arabian Peninsula and beyond right the way down to 1900. So, the first half of a century-long campaign against the illegal movement of enslaved peoples across the world ended. The House of Commons and the British people generally supported this campaign throughout its long and grinding duration, testament to the commitment of the nation to deal with this issue in a thorough and effective way, and the skill of the naval officers and men who delivered this result, and of the politicians who oversaw it. This needs to be better recognised.   Perhaps it is for this that Lord Palmerston has a statue on Parliament Square. Thank you very much.

Thank you very much, Professor Lambert. There’s Palmerston, yes. And for very interesting talk which taught me a huge amount that I had no idea about. I’m going to provide a little breathing space for our audience by asking you a first question if I may. Could I suggest to all the participants that they should use the question and answer, the Q&A command at the bottom of their screen and write in their questions, or indeed I suppose you could use chat, but if we all use the Q&A that’s probably easier. So please do write in your questions and I will select them and pass them on. I was very interested. Well, I have lots of potential questions, but could I start by asking you to say a little bit more about one of the heroes of your story who is Captain Denman. What sort of a man was he? What was driving him in his commitment to abolitionism?

Joseph Denman was a very successful naval officer who came from a family of abolitionists. So, this was not just personal, this was a familial commitment. And he had chosen to serve on this station more than once. So right through his career he sees this as the station where he should be deployed and it is his commitment that leads him in the case of Gallinas to essentially overstep his instructions and to land on the territory of a foreign power and commit acts of both violence and destruction. If a Royal Navy Captain did that today I suspect his career would come to a grinding halt. But the popular support for Denman’s action and the support of the Foreign Secretary meant that instead of being penalised he was lauded, and his career went on up to the rank of Admiral. So, what we look at is a relatively small number of officers whose commitment to this cause is such that they deliberately picked this out as the place they want to serve. It’s worth noting of course that in peace time, so after 1815, your chances of getting promoted for doing something brave and brilliant evaporated. Defeating the enemy was no longer an option. This was a place where men could display skill, seamanship, and judgment, to do something noteworthy, and it was in those days perfectly possible to be promoted for distinguished service. So, I think we have to give Denman the credit for being absolutely committed, but it didn’t do his career any harm to do great things on this station. He was one of many young officers whose career was made by the success he had in delivering the anti-slavery patrol. So, if you get your name in the public print, you could get a letter published recording what had happened, there was every possibility that the Lords of the Admiralty would move you up a step. That was something that many young officers had no other means of achieving. So, this was quite attractive because it was a live and dangerous station and you could make your name here. We’re looking I think at two things: both a noble commitment and a desire for professional advancement.

Is it true that it was also very risky in the sense not only because you might get Malaria, but you could lose a legal case and were you’ve not then held responsible personally for damages or something of that kind.

Yes, in in Denman’s case the damage he’d done was enormous. He destroyed an entire slave factory, and it would certainly have bankrupted him had he been found liable. But also, with illegal captures and that is the case in war as well. So, in the in the Anglo-American War of 1812, American ships were illegally captured could be returned with damages and you would be liable for that as an individual. In the 21st century HM Government would cover those costs for you but in the 1810s that was not the case. You would lose your shirt as well. So it is dangerous in economically, it is also dangerous because many of these actions necessarily involve boarding vessels, that’s a physically dangerous business and the slavers tended not to surrender unless they were absolutely forced. The usual way of stopping in a merchant ship at sea in the age of sail is to knock the sails down. Then have to persuade the crew to surrender and that means firing into the ship itself, which is something that Royal Navy crews were unwilling to do when the ship was packed with human cargo. So, you tended to use boarding action rather than gunfire to stop and capture these vessels. The casualties in hand-to-hand combat were a significant element. Once you’ve captured the slave ship and then began to release the people you may well find that the people on board are subject to an endemic disease, and this will then infect your crew. This happened on several occasions. The Royal Navy was very quickly persuaded the best thing to do was to remove the crew and the enslaved people and destroy the vessels. Because any slaving vessel that was sold on the open market ended up back in the slave trade, they would destroy the slaving vessels very publicly to make sure they weren’t re-used.

I was going to ask you a bit about the practicalities of it. Obviously, you wouldn’t want to fire into the hull of a ship packed with slaves but on the other hand you as you were saying you’ve got to capture it with its human cargo in order to prove it was a slave ship, until the clauses that allowed you to identify it by barrels of water or manacles or whatever. So presumably they sometimes fired at the sails? One of your pictures I think seemed to show that.

Yes, and the slavers would be doing exactly the same thing, trying to slow down the chasing vessel by knocking its rigging away. Your ability as a sea officer, a skilled seaman to catch one of these fast-moving vessels was a very high test of professional capability. Remember they’re firing primitive muzzle-loading smoothbore weapons, these are not precision tools, so you’re asking a great deal of your crew in doing that. There is I think a great level of commitment on the part of those involved which was only reinforced by the experience of capturing and boarding one of these vessels and realising just how horrific the conditions were. So, we find some officers and men who went on the patrol because they were sent there, coming back as committed abolitionists and public proponents of abolition. This nasty experience was life-changing for many people.

Quite a few questions have come in. Two about numbers. One, could you say what, roughly speaking, the relative size of the trade into Brazil and South America as opposed to that into North America was?

Thank you, that that’s a very good question and it’s a moving target. Down to the late 1840s Brazil is a very significant part of the number. 40 perhaps 50% of enslaved people are going from south of the Equator across into the Brazilian economy. And with the closure of the Brazilian market the overall numbers in the trade drop but obviously they’re now going through Cuba and many of them are ending up in the United States, despite the stipulations of Congress that this was illegal and equivalent to piracy. So, it’s constantly moving but the numbers across the period show around 12 million people moved in the period from 1815 through to the end of the trade in 1860s. So that gives you a rough idea how many people are being moved every year. The figures were fairly stable across the period until well into the 1850s when they start to drop off.

One question is about the alternative markets for West African traders. Were there alternative markets for slaves taken from West Africa? They weren’t sailed round the Cape of Good Hope up into the Indian Ocean presumably? Were slaves for the Arab Market taken either overland or from East Africa?

Yes, I think that is the right conclusion. The overland trade through Egypt provided a route into the Arabian market. East African slavery is a very large issue and has been for even before the Europeans arrived in the Indian Ocean. This was a very big trade with well-established patterns which the Europeans blundered into when they rounded Cape Horn. Very limited amounts of movement of peoples from West Africa by ship into the Indian Ocean, it was too far, and you were too likely to run into British warships. So, it tends to be the overland and East African trade that is servicing into the Arab market because there is plenty of demand in in the New World. And it’s a question where the demand is that’s driving this. There is still demand for an East African trade long into the 19th century, long after the West African trade demand had dried up.

I remember one of my Africanist colleagues John Iliffe saying, and he’s written this, that African traders, African sellers of slaves, were threatening to kill their slaves if Europeans didn’t buy them. So, when the British were trying to put a stop to the trade on the West African coast, there were there were threats against slaves by rulers and slave Traders who were saying “well if you won’t buy our slaves we’ll just kill them”. So, it shows that there was no there was no alternative to the Americas as a market.

I think that that’s good evidence. But it also emphasises the point that we have to bear in mind that these men were trading in a commodity. They have no sense that these are human beings. This is something that they are trading and if they can’t bring it to market in an economically attractive way, they will dispose of it in a way that costs them the least money. Why would they maintain a large number of people alive if they can’t sell them for profit?

While the British are looking at this very much in in terms of morality, the people running the trade are looking this in very much in terms of economics. The synergy there is between those people saying that if they can’t move their slaves they will kill them, and the Anti-Corn Law League saying, “well we don’t want to pay a premium either to see this horrific trade ended or indeed for the sugar, we want to buy very cheap food and we don’t want to pay any taxes for anything like this”. The fact that this went as a vote of confidence in the House of Commons in a government that they as part of, the Liberal Party they were allegedly supporting, is telling. The domestic agenda was very important, and maintaining support for this patrol was a critical part of the messaging that’s coming out and in the newspapers, most of which is very positive, through the Foreign Office and through Palmerston. Palmerston was managing the press quite brilliantly in all the things that he did, but this was a particular interest of his. At the end of his life Palmerston said that he was proud of two things: he had stopped the Atlantic slave trade and made his country safe against an invasion. They are both tasks that the Royal Navy conducts so it’s no accident that he’s supporting the Navy and supporting men like Denman who are solving the problem that’s being raised by this trade.

I suppose what we’ve been saying shows that it was also important to provide alternative sources of income for West African rulers. I know palm oil, which is now also something that we disapprove of, was then seen as an alternative industry and export item wasn’t it for those who had previously been involved in selling people.

Yes, the development of an alternative was a key part of the strategy. Obviously, it’s not the Royal Navy’s job to introduce people to the new trade goods but palm oil picks up in this period because it is an alternative crop. And we also see missionary societies promoting this idea, so we get early attempts to ascend the major rivers of West Africa and open up trading relations with inland powers in West Africa almost all of which end with the usual catalogue of Malaria and Yellow Fever deaths and failure on a large scale. But technology is starting to play a part. By the 1840s there are iron steam-powered vessels that can go up West African rivers in ways that had never been possible before. By the 1870s, medicines are starting to be available that will help deal with some of these problems. It’s no action that Britain has a very large school of tropical medicine right in London and it’s closely connected with the Navy. Keeping naval personnel alive is a really good thing whether it’s Scurvy, Malaria or Yellow Fever.

A few more questions, indeed, quite a few more questions I’d like to pass on to you. In one of your tables, you pointed out the percentages of embarked slaves who did not arrive. Presumably largely from disease on route. The questioner asks: “How different was this percentage of mortality from that of sailors or passengers on similar ships?”

Thank you that that’s a very good question. Anybody sailing in West African waters close to the coast is at risk. This is not a benign environment because for the slaves many of the diseases they’re dying of are not West African diseases, they’re diseases connected with travel. They’re also dying of despair, homesickness, alienation the violence of the crew. Slave ships don’t all make it and these very fast American-designed Schooners are very dangerous vessels they are overmasted, they have far too much canvas that they can spread They were known to be vulnerable to sudden squalls which would literally knock them over sideways and sink them. So, the Royal Navy always reduced the amount of sail that these vessels captured if they tried to navigate them. Extremely dangerous means of transport and driven by the need to outrun the anti-slavery patrol. The 18th century pre-abolition slave trade is run in standard merchant ships. Speed was not an option that they need to worry about. The delivery of the cargo in relatively good health is the thing they’re concerned about, but after abolition the trade shifts. And some missionaries complained that the Royal Navy’s patrol was actually making the passage more dangerous for the slaves, rather missing the point that the best thing was not to be enslaved in the first place, to cross the Atlantic because they were crossing in such dangerous vessels. So a significant number of those casualties are not disease casualties they’re marine accident casualties. Slave ships disappear because they’re over masted, they’re trying too hard, and they’re overloaded on occasion as well. So there are a range of causes of death, including scurvy.


I think this may be a question that you may not want to comment on. We may come on to this in a later lecture, but if you can please do. One question asks if you could comment on the Indian slave trade. And he comments that his wife is a descendant of plantation slaves in Madras.

No unfortunately you have found me out. That is not an area where I’ve done any work at all. I’m very sorry to say I don’t have a position I can offer you on that. I think what the question emphasises is that we have to see this in a global context. That slave trading is going on in many places across history and in between many different communities. The entire ancient world is powered by slavery. So when we look at one slave trade, we have to be aware that we are only looking at one part of this complex issue and this is a part of the slave trade that Britain was in a position to do something about and the question that may be asked of the trade in India is: who is doing the trading and what is the relationship of that trade with the regional Powers? But as I say I don’t have an answer, but I think getting that question in context is going to be important to understanding: what’s going on and where the responsibility lies, who is commoditising these people, who is purchasing them, and how does the market work. So, if we treat this rather grimly, in purely economic terms, we can start to see what’s going on.

Thank you, Andrew. We shall be doing a longer series on the history of slavery next year and we shall certainly be talking about Asian slavery, both Indian and Chinese, and elsewhere. But you touched on the economics and of course as you pointed out this was always a very profitable trade in a certain commodity. Some historians, some quite a long time ago and some very recently, have argued that British policy was really cynical, it was not a humanitarian policy it was aimed at either just expanding territory in West Africa or was aimed at the profits of trade with West Africa and that that the suppression of slavery was simply a by-product of this at best, or an excuse at worst.

Yes, that’s an argument that’s certainly come around twice already. It is a very significant argument and I suspect there is some connection between the contemporary period and the historical writing of other powers who were willing and indeed anxious to continue trading in slaves. There’s a Belgian narrative about the slave trade which is very different and indeed makes many of those points that Britain is simply doing this to damage other people’s economic interests. I think the last major museum in Europe that hadn’t overhauled its interpretation of relations with Africa in the 19th century was in Brussels. The French would certainly take this view in the 1820s, “here are the British using their power to stop us doing something and then pretending it’s a moral issue”. So of course, the British economy in the West Indies is changing and the only reason that the British are able to abolish the slave trade and then to abolish slavery as well is because the political consequence of West Indian merchant traders and plantation owners is ebbing away. 1833 is the year after the Reform Act has changed the basis of political power in England. And those two things are absolutely connected. An unreformed Parliament would almost certainly have had more interest in plantation slavery at the very least, and may well have blocked that move. But the reformed Parliament was able to push that through. So, I can’t imagine that anybody looks at this in the period that these decisions are being taken without considering those issues, because that would be remarkably unprofessional. But on the other hand, this is a moral imperative which has been voted through in the middle of the greatest war that Britain had to that date ever fought by a very determined government with the support of the House of Commons. I don’t see this as some kind of conspiracy, I do see it as a demonstration of popular support for the cause. The cause of abolition had been strong long before the abolition of the trade, let alone the abolition of slavery. So there may be interpretations that suggest it’s a purely cynical move. I would suggest that it may be a combination of both. I tend to find that the more extreme interpretations that need to be modified by the practical business on the ground.

The British government could do this because the power of this of the 18th century slave economy in the West Indies had been greatly reduced by the rise of other economic factors. That doesn’t mean the British didn’t stop this for moral reasons. I think both interpretations are there and it’s very much a question of balancing your assessment of where you think the primary driver of this lies.

And at quite considerable cost, after all. Both the cost of the patrol itself, the Navy’s commitment and effectively ransoming the slaves by paying off their owners. Was the cost of the patrol considerable?

Yes, the anti-slavery patrol is a very significant element of the Navy’s budget. After 1815, this enormous Navy that the British had created to fight the French and the Americans and everybody else, almost all of it was paid off, almost all of the sailors are released from service and it would not be mobilised again in large numbers until the First World War. The anti-slavery patrol was about 15 to occasionally 20 percent of the active Royal Navy deployed outside UK Waters. And given the global reach of the Royal Navy and the range of tasks it was conducting that was a significant figure. These are small ships, but numerous.  The turnover of ships and crew is rapid. Tropical waters are not good for ships, let alone people. The hot wet conditions are very negative for northern European-built ships which is why the Royal Navy used a lot of ships built in Bombay from Indian teak. And you will find teak-build ships operating in this theatre because they’re more durable.


And that includes the Trincomalee which was built in Bombay in 1817 and was then deployed to the Caribbean. Again, another hot wet climate. And still here, so let’s go have a look at if we’re in that part of the world.

There’s a final question, I guess then we should let you go as you’ve been very patient and given us a very full measure of your knowledge on this subject. Someone has said: “well the threat to kill slaves (which is something I mentioned) well surely they could have just let them go” and I think I ought to answer that question which is simply the risk of having a lot of freed slaves running around was too great. Normally you would capture slaves and sell them on as fast as you could. You couldn’t risk having a lot of freed slaves around with natural resentment against what you’ve done to them.

You see this on the on the West African coast where in some places the remains of these fortresses, which are essentially defended prisons, remain. Places where the enslaved peoples were kept until they could be shipped off. There’s a great synergy between the local suppliers, the agents who are going to handle the finances, the transport links and then the final purchasers on the other side of the Atlantic. Taking out different pieces of that system in different places compromised and ultimately degraded the trade; the introduction of alternative trade patterns, and alternative exchanges of goods began to weaken the dominance of this West African export commodity. And ultimately the closure of the American markets finished it.

The Royal Navy didn’t stop the Atlantic slave trade but it made it more and more difficult for that trade to persist and it was able to stop parts of the trade with the Brazilian trade being the standout item. And then it was there right at the end when the American trade disappeared as well. It’s very difficult to stop long established trading patterns when you’ve got supply, demand and willing transport systems and what the Royal Navy was doing was taking out the transport system as far as possible but as we know in illegal activity to this day, where there are cargos that are that can be carried at high price, there will always be individuals who are prepared to take that risk in order to acquire the economic rewards.

Well, if I’m not presuming too much on your patience, could I ask you two last, very quick, questions. One sees a lot of somewhat different figures for the number of people released by Royal Navy ships from captured slavers. What figure would you give? That would be one of my questions and the other one which I think you can probably answer very quickly: when as far as you know is the very last Royal Naval action against a slave ship anywhere in the world?

I’ll answer the last one first. It was probably last year, it would have been stopping and searching a ship probably in the Arabian Gulf / Indian Ocean region that was carrying migrant workers who have been recruited illegally. People trafficking is still going on and the Royal Navy is still doing the same job. If there’s enough intelligence you can stop ships that are trafficking people and release them. This is ongoing business this this has never finished. The figures that are given, and you’re right Robert there are many figures, I don’t think any of them are correct. I would look at them all and probably just average them out and just accept that we’re never going to have a really accurate figure for this. There are so many reasons why the figures will not be accurate, not the least of which is of course that the Royal Navy captors who released the slaves were paid head money. They had an interest in inflating the numbers of people they’d liberated. Later on, when the equipment clause came in, the government had to give them prize money for the vessel to make sure that they were sufficiently motivated to go after empty ships. I don’t think any of these figures are absolutely reliable but I think if we average them out we get an indicative figure which is significant. But it’s not a figure that is going to end the trade. In no year does the Royal Navy release more than 50 percent of the slaves transported across the Atlantic. It would be a much lower figure than that year on year. And as a result, they are never going to stop this trade. As long as there is demand on the opposite side of the Atlantic that is the ultimate mechanism by which the trade will be ended. When the last Commodore in West Africa says that “there is nothing happening here, it’s over, we can stop doing this”, it is because nobody is buying slaves in the New World. It is illegal in the United States now, Brazil has long since ceased importing, but Brazil has not abolished the status of slave. And it will not do that until the 1880s. Slavery persists in the new world but the trade that supports it does not.

On that note, let me thank you again, Andrew, for that fascinating lecture and for you’re very interesting slides too. And to thank everyone who took part and those who asked such interesting questions. Thank you, Ladies and Gentlemen and thank you again, Andrew.

Thank you, thank you everyone, it’s been my pleasure.



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About the author


Professor Andrew Lambert

About the author

Robert Tombs

Robert Tombs

Robert Tombs is Emeritus Professor of French History, Cambridge, and a Fellow of St John’s College. He holds the Palmes Académiques for services to French culture. Recent works include The English and Their History (2014), Paris, bivouac des révolutions (2014), and This Sovereign Isle: Britain In and Out of Europe (2021).