Slavery, Ships and Sickness

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The full-rigged ship was the essential technology that enabled the trans-Atlantic slave trade to flourish. Between 1698 and 1807 around 11,000 ships were fitted out in England for the slave trade, transporting around three million Africans. But the trade also employed other vessels, from in-shore boats supplying the slavers, to the Navy vessels that protected them. Sickness and disease were constant companions to both slaves and crew. Mortality amongst both was high, from disease, mistreatment, accident and suicide. Dr Stuart Anderson explores the relationship between ships, slavery and sickness, and considers the measures eventually taken to improve health at sea.   This is part of the Great Days of Sail Mondays at One series. The other lectures in this series are as follows:       The Greenlanders - Arctic whaleships and whalers       ‘They live by Trade’: Britain’s global trade in the Great Days of Sail       Why Conserve the Cutty Sark?

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24 October 2011

The Great Days of Sail

Slavery, Ships and Sickness

 Dr Stuart Anderson

Associate Dean of Studies

London School of Hygiene and Tropical Medicine


Origins of Slavery

Slavery is a vast topic that has been the subject of enormous scholarship in recent years. In this talk I want to focus on the Atlantic slave trade, on Britain’s involvement in it, and on the part ships played in the trade. Ships were the essential technology that enabled the slave trade to flourish. Ship construction evolved greatly over the centuries that the trade continued, resulting in bigger and faster slave ships. Navy ships too played their part, first in protecting the slave ships, and later carrying out anti-slavery patrols. But for everyone involved with the trade, sickness and death were constant companions.

Slavery and slave markets were a common feature of the ancient and medieval worlds. In Africa there were established slave routes to Tunisia, Libya, Morocco and Egypt. Cairo was a major staging post for slaves in the Mediterranean world. Slaves were bought and sold by middlemen, and often transported over great distances. The Greeks and Romans recruited slaves from the lands around the Mediterranean and beyond. By the fifteenth century Arabs had established slave posts on the East African coast, from where they were shipped to the Persian Gulf and India. Slavery and the slave trade were thus well-established on several continents for centuries before Columbus discovered the New World in 1492.

Portugal was the first European power to become involved in Atlantic slavery. Prince Henry the Navigator sponsored raids on the West African coast in the 1440s, and black Africans were brought to Portugal. A trade was established involving African chieftains, mainly in Mauretania and Upper Guinea, selling captured slaves to the Portuguese; some of these were then re-exported to Spain. The Pope gave his blessing to the trade in a bull of 1442; enslaving Africans fell within the limits of a ‘just war.’ This was extended in an edict of 1452, which gave Portugal the right to enslave captives taken in such a war. Up to this point the movement of slaves was from west Africa to southern Europe.   

Following Columbus’s discovery of America, Portugal moved quickly to protect its interests against its rival Spain. At the Treaty of Tordesillas in 1494 Portugal claimed the right to possessions south and east of a line 270 leagues west of the Azores, while Spain claimed the right to dominions north and west of the line. Portugal claimed Brazil in 1500 following the arrival of Pedro Cabral, and began sending settlers to Pernambuco in the north-east of the country.

The Treaty also gave Portugal commercial rights in Africa. They began building forts in Gambia and along the Gold Coast to protect their interests, which included slaves and gold. In the early sixteenth century Portugal started shipping African slaves to several of its Atlantic island possessions, including the Azores, Madeira and the Cape Verde islands, to work on sugar and cotton production. In Brazil, settlement rapidly extended throughout the region, and the first African slaves were introduced in 1538, many being re-shipped from the Atlantic islands. In the 100 years between 1551 and 1650 around 250,000 slaves arrived in Brazil, with most disembarking at either Rio de Janeiro or Salvador.

The first African slaves taken to Spanish America arrived on a Portuguese vessel in 1502. The Spanish authorities were keen to expand the slave trade, and in 1521 the Emperor Charles V instigated the system of asiento, which legalised the shipment of slaves to Spanish America under a royal licence. Slavery flourished in Spanish America as a result of sugar cultivation, gold mining and the asiento. Between 1551 and 1650 the Spanish colonies received about 190,000 slaves under the asiento, and many thousands of others smuggled in unlicensed ships. Slaves were delivered mainly to the ports of Cartagena, Veracruz and Buenos Aires.

The origin of English involvement in the Atlantic slave trade is normally traced to the middle of the sixteenth century. In 1556 a London trader, William Towerson, returned to Plymouth with a number of slaves collected on his voyage to Africa. He made a second voyage the following year. Both were financed by merchants in London and Bristol. But Towerson did not transport slaves across the Atlantic, and it is John Hawkins who is usually considered the founder of the British slave trade. His first voyage to West Africa and the Caribbean began in 1561. He formed a syndicate of wealthy merchants to invest in the slave trade, and set sail with three ships for the Caribbean. They attacked and captured a Portuguese slave ship, and sold the 301 slaves on board in Santo Domingo, in the Dominican Republic. Hawkins led two further voyages.      

For his second voyage in 1564 the Queen, Elizabeth I, loaned him a large vessel, the Jesus of Lubeck, and he was dubbed ‘Queen Elizabeth’s slave trader.’ He set off along with three smaller vessels, and went hunting for the slave ships of other countries. He captured around 400 slaves and headed for Borburata, a small coastal town in Venezuela, which had been founded in 1548. Hawkins’ third voyage began in 1567. He obtained slaves on the African coast, and added to them by capturing a Portuguese slave ship, the Madre de Deus.In total he transported about 400 slaves across the Atlantic to Veracruz in Mexico.

Ship construction

Until the fifteenth century voyages by European mariners were limited by the construction, size and rigging of their vessels. But from about 1450 existing designs such as the cog were superceded by a new type, the full-rigged ship. This was in fact the major innovation in ocean transport until the invention of iron, steam-powered vessels in the mid-nineteenth century. Before full-rigged ships, vessels were ‘shell-built’, that is, from the inside out. The planks forming the outer skin of the vessel were joined together at their edges, and this shell was then made rigid by the insertion of strengthening frames. Ships were built the other way round. A skeleton, starting with a backbone, or keel, was laid, posts and frames were added, and the whole was covered with a skin of planks. This enabled bigger, stronger ships to be built; ships that were able to carry heavy guns, and sufficient men and supplies for long journeys.

This new building technique probably originated in Spain. It was accompanied by the development of

the three-masted sailing rig. Square sails, that is, those at right-angles to the mast, were carried on the bowsprit (the mast projecting over the front of the ship) and the fore and main masts. A triangular lateen sail was carried on the mizzen mast at the back or stern. The first full- rigged ships were a type known as carracks. Columbus’s Santa Mariawas of this type.The Santa Maria had three masts, each of which carried one large sail. The foresail and mainsail were square; and the sail on the mizzen mast (at the rear) was a triangular sail, or lateen.

John Hawkins made further important improvements in ship construction and rigging. He introduced the idea of sheathing the underside of his ships with a skin of nailed elm planks, over the bottom timbers, sealed with a combination of pitch and hair, as a protection against the worms that attacked ships in tropical waters. Hawkins also introduced detachable topmasts that could be hoisted and used in good weather, and stowed away in heavy seas. Masts were placed further forward, and sails were cut flatter. Hawkins’ innovations made the new English ships fast and highly maneuverable. In 1588 they were tested against the Spanish Armada, at which Hawkins was one of the main commanders along with Sir Martin Frobisherand his second cousin Sir Francis Drake, who ten years earlier had circumnavigated the globe in the Golden Hind.

Both England and France coveted the colonial wealth of Spain. English privateers (armed ships sanctioned by the state to capture foreign vessels and claim their cargo as prizes) repeatedly attacked the Spanish treasure ships transporting the silver back to Spain in the late sixteenth and early seventeenth centuries. Between the 1580s and the 1630s England began to establish colonies in the West Indies and North America. These included St Kitts in 1624, Barbados in 1627, Nevis in 1628 and Montserrat and Antigua in the 1630s. The colonies would provide opportunities for white settlers, large numbers of whom migrated from England. By the end of the seventeenth century around 350,000 English people had crossed the Atlantic, with most settling in the new colonies. Relatively few returned home to live there permanently.

The demand for slaves

It was the explosive growth in the demand for sugar in the middle of the seventeenth century that drove the need for slave labour. Sugar cane was introduced to Barbados in the mid-1640s by Dutch merchants and planters who had been expelled from Brazil by the Portuguese. The island was claimed by England in 1624, and became a Crown colony in 1663. By 1680 the sugar crop had transformed the island into what was described as ‘the richest colony in English America.’ Sugar cultivation spread rapidly to other Caribbean islands, reaching Jamaica in the early eighteenth century.  

Cultivating sugar was extremely labour intensive. Other labour options had been tried before African slaves became the preferred option. In South America the Portuguese used local Indian labour for sugar cultivation. The settlers found this source of labour insufficient, and it was also opposed by local Jesuit priests. England tried indentured labour in the West Indies, but at the end of the period of indenture labourers expected not only their freedom but also land of their own. Throughout the Americas and Caribbean plantation owners found it impossible to recruit sufficient numbers of either the local population or white immigrants who were willing to do the work. The only other option was slavery, and there were plenty of people only too willing to meet the demand.

But sugar was not the only commodity that thrived in the Americas and Caribbean. By 1620 Virginia had begun to produce tobacco, and this became the major export of both this colony and its neighbour Maryland over the next 150 years. These two states were together known as the Chesapeake. Other commodities were sourced in South America. There was a gold boom in Brazil between 1680 and 1750, followed much later by a coffee boom. Cotton, cocoa and rice, amongst other crops, became significant exports from the West Indies between 1660 and 1850. Cotton became the major export of the southern United States from around 1790.

The Royal African Company

The period following the restoration of the monarchy and the return of Charles II in 1660 saw a marked shift in Britain’s involvement in the Atlantic slave trade. In the same year, Charles granted a charter to a group of English merchants, to be known as the Company of the Royal Adventurers to Africa. Charles himself was a shareholder. The object was to supply the English sugar colonies with 3,000 slaves a year at an average price of £17, or the value of one ton of sugar per slave. More than half of the original thirty-two Royal Adventurers granted the Charter were peers or members of the Royal family. But by 1667 there were also forty-nine untitled shareholders, most of whom were established merchants in the city of London. They included fifteen Lord Mayors of London and a number of MPs.

Twelve years later, in 1672, the Company was re-organised, changing its name to the Royal African Company. Under its Charter the company held a monopoly in English trade to Africa, which it retained until 1698. During its most active period, between 1680 and 1688, departures from England to Africa totalled 249, or around forty per year. It also sold slaves to individual slave ships, and to other companies such as the South Sea Company. In addition to its ships the Company built around twenty establishments in West Africa, which were called ‘forts’ or ‘factories’. The forts were designed to be permanent settlements, and were usually built of stone. Typically they housed a group of Company employees and a small garrison, although most were not permanently manned. Only two, those at Accra and Cape Coast, were continuously occupied between 1672 and 1713. Factories, on the other hand, were usually unfortified, and were staffed by only a handful of men.

In 1698 the Company’s monopoly was removed, and the trade opened up. After its peak the company declined rapidly. In 1729 it delivered only 563 slaves to the colonies. Private operators entered the trade legitimately, and shipments of slaves in English vessels rose dramatically. In fact, the number of slaves shipped averaged more than 20,000 a year through most of the eighteenth century, reaching 30 to 45,000 a year during the last decade. Overall, almost 11,000 ships were fitted out in England for the slave trade between 1698 and 1807. Slaves were also transferred between one destination and another, particularly from the smaller Caribbean islands to others and the Americas.

By the late seventeenth century the triangular nature of the trade was well established. Ships left England for Africa laden with goods that were traded for slaves; the slaves were transported across the Atlantic to America or the Caribbean (the infamous ‘Middle Passage’), and the ships returned to England laden with the sugar, cotton, tobacco and other commodities grown on the plantations. Until the early seventeenth century Amsterdam was the hub of the Atlantic system. But by the mid-seventeenth century London was starting to occupy this role. It developed an integrated financial, insurance, trading and shipping system, along with the necessary infrastructure of docks and shipyards, attuned to the needs of the trade in Africa, America and the West Indies.

Slaving ports: London, Bristol and Liverpool       

London’s pre-eminence in the slave trade was soon challenged. By about 1700 Bristol was joining in the slave trade, its merchants keen to grab a share of the enormous wealth being generated by the Atlantic trade. The shift from London to Bristol was rapid.  In 1725, eighty-seven slave ships cleared London, as opposed to sixty-three from Bristol. By 1728-29 half the British tonnage heading for Africa came from Bristol, which became Britain’s biggest slave trading ports during the 1730s and 1740s.

By the late 1720s Liverpool had also become involved. Between 1726 and 1730 only eight ships left Liverpool for Africa. But from 1731 to 1745 the number rose rapidly, and between 1750 and 1775 over a quarter of all Liverpool shipping was involved in slavery. By the mid-1740s Liverpool had overtaken Bristol. The annual average clearances for slave ships during the 1730s were thirty-nine for Bristol, twenty-five for London and twenty-one for Liverpool. The average number of slave ships leaving Liverpool each year was ninety-five between 1772 and 1775, eighty-eight between 1783 1792, and 107 between 1793 and 1804. It remained dominant until abolition in 1807. In that year, the last year of the legal British slave trade, Liverpool despatched 101 slave ships.At least 176 Liverpool merchants were involved in the slave trade, mainly in the Chesapeake area.

Historians have investigated the reasons why, first Bristol overtook London, and then Liverpool overtook Bristol. Bristol was already an established provincial port by the early eighteenth century. It was favoured with a westward outlook, so it was well placed geographically to trade with Africa and the Atlantic world. But of much greater importance was the enterprise shown by Bristol merchants in exploiting opportunities for selling slaves in colonies such as Virginia and St Kitts; they also concentrated successfully on supplying slaves to England’s largest sugar island, Jamaica. Bristol lost ground to Liverpool during the war years of the 1740s (the War of Jenkins Ear 1739-42, and the War of Austrian Succession 1744-48). Bristol merchants cut back on slave voyages during the conflict. In fact they converted many of their ships into privateers; robbery was more profitable than trade. But Bristol’s location was a problem in wartime; French corsairs and Spanish warships could pick off its vessels sailing to Africa in the mouth of the English channel.

Liverpool merchants did not switch to privateering to the same extent. They also had the advantage of a more northerly port, from which ships could sail around the north of Ireland and into the Atlantic, safe from sea lanes patrolled by foreign warships. Liverpoolmerchants were also more flexible than those in Bristol, who were largely split into distinct groups of tobacco, sugar and slave merchants, with very limited movement between them. Liverpool merchants moved freely between commodities. Liverpool also had a far greater commitment to building slave ships, giving its local merchants rapid access to new vessels.

A number of smaller English ports were also involved in the transatlantic slave trade, including Whitehaven and Lancaster. Whitehaven flourished briefly in the middle of the eighteenth century, whilst Lancaster had a brief period of activity in the two decades before the American War of Independence in 1775. But both lacked the network of commercial contacts needed for success in the trade, coupled with not so easy access to the manufactured goods needed for export. Glasgow had very little direct role in the British slave trade, although some Scottish merchants participated in the trade through London.

Designing slave ships

During the course of the seventeenth and eighteenth centuries the size of vessels taking part in long distance trade gradually increased, although quite a number of small vessels, some as small as 20 tons, are known to have been involved in the trade. In Liverpool it has been estimated that the average size of a bulk vessel in 1709 was about seventy tons. As Liverpool came to prominence in the mid eighteenth century the size of vessels increased, to around 100 tons in 1765, doubling to around 200 tons by the turn of the century, although there were even bigger ones. The situation varied from port to port. By the end of the eighteenth century a distinction was made between a West Indiaman, trading directly with the West Indies and usually London-built, and a Guineaman, engaged in the slave-trade and usually Liverpool-owned and built. 

The design of purpose-built slave ships proved challenging. The hull shape had to facilitate good speed during the Middle Passage; the ship had to have some defence against attack, and at the same time it had to be capable of carrying a large return cargo from the West Indies. Merseyside Maritime Museumholds the painting by William Jacksonof a Liverpool slave ship of around 1780 which illustrates the main features. There is a half-model of the slave ship Alexander in the Science Museum, which has fine lines with a sharp bow, raised floors amidships, and a long smooth run to the back of the ship. She is pierced with eighteen guns, and has large hatches, which suggests that she may have been a Guinea man. Internally the ships usually had a flexible layout because of the different cargoes on the three stages of the journey. In the first stage they had to pack in as many trading goods as they could, a typical cargo including such items as guns, copper and iron rods, and textiles. Off the African coast they were reconfigured to maximise the number of slaves that could be taken on board.

The way the slaves were loaded was graphically illustrated in the famous plan of the Liverpool slave ship Brookesof 1781, drawn for parliament’s attention in 1786. TheBrookeswas about 100 feet long, 27 feet wide, and was of 320 tons. The height between decks where the slaves were kept was 5 ft 8 inches. The plan shows a platform in the ‘tween deck which projected six feet out from the sides of the ship. The diagram shows where 451 slaves could be stowed. In fact, under a new law passed in 1788 she was permitted to carry 454 slaves. According to a surgeon who had worked on her she had previously carried 600 slaves on one voyage and 609 on another.

The Brookes was by no means the largest slave ship which operated out of Liverpool. A ship of 566 tons called the Parrwas launched at Liverpool on 18 November 1797. The press notice at the time declared that ‘she is looked upon by judges to be a very beautiful vessel, and the largest out of this port in the African trade for which she is designed.’

Further improvements to ship design were made in the mid-eighteenth century, the most significant of which was the introduction of copper sheathing. In 1761 the frigateHMS Alarm, part of the West IndiesFleet, had her entire bottom coppered, in response to the terrible condition in which she returned from service. But it was soon discovered that the copper bolts used to hold the plates to the hull reacted with the iron bolts used in the construction of the ship, rendering many bolts useless. The Navy solved the problem by replacing the iron bolts with copper ones. The method was effective, and was quickly adopted by virtually all merchant ships sailing to the tropics, including slave ships.


Throughout the period of the Atlantic slave trade virtually all the slaves originated from western areas of Africa. British ships took their slaves from seven main areas; Senegambia (now Senegal and the Gambia), Sierra Leone, the Gold Coast (now Ghana) the Bight of Benin (Nigeria), the Bight of Biafra, and West-central Africa. In all, this area covers between 3,000 and 4,000 miles of coast, from the Senegal River in the north, to Benguela in Angola in the south. North of Senegal the terrain was either Sahara desert or controlled by Moroccans. Slaves were available south of Angola, but this was impractical given the distance from Britain and the costs of getting there. 

Sickness was an ever-present feature of the slave trade, and not just amongst the slaves. It was one of the reasons why attempts to co-opt Indian labour into agricultural production in North America failed, along with cultural differences and conflicts over land and resources. Epidemics occurred from time to time, in which large numbers of Native Americans died as a result of tuberculosis, pneumonia, influenza, plague, measles, scarlet fever, smallpox and malaria. Many of these resulted from contact with people from a different disease environment. Many of the English settlers had experienced these diseases as children before crossing the Atlantic. They had at least some immunity to them, but native communities were quickly decimated by contact with carriers of these diseases. The same was true for the native Caribs of the West Indies. 

There were strong incentives for getting slaves to markets as quickly as possible, for keeping the sea journey as short as possible, and for having as many survive as possible. But this was not easy in tropical regions where lethal diseases were endemic. Mortality and sickness rates varied considerably depending on circumstances, and particularly on the stage in the slave journey. Slaves were often captured far inland, and long distances were covered on foot, often taking months to reach the coast of Africa. Starvation and injury were hazards on top of disease and attack, and it is likely that mortality and sickness rates were highest during this first stage of the journey.

We know rather more about mortality and sickness once the slaves reached the coast, although the records kept about the export of slaves are much sketchier than those relating to import into the Americas and Caribbean. The fate of the slaves varied considerably. Some were kept in enclosures on land called barracoons; others were held in forts or compounds, and still others were kept onboard ships of one sort or another.The pattern of mortality depended on how long slaves were held captive on the African coast awaiting shipment. The longer they were kept in compounds, the greater the chance of disease breaking out.

Death during the Middle Passage occurred largely through diseases caught in Africa. The prime cause of death was gastrointestinal complaints, caused by dirty, unhygienic conditions. Flux, dysentery and severe diarrhoea were the chief symptoms. Dr Alexander Falconbridge, who had been a surgeon on English slave vessels, noted that some ships’ holds were ‘so covered with blood and mucus in consequence of the flux, that it resembled a slaughter house.’ But there were also deaths from dropsy, scarlet and yellow fever, malignant fever, tuberculosis and a host of other diseases. The incidence of disease followed the normal pattern of epidemics; deaths reached a peak during the first third of the Middle Passage, before falling and leveling off later in the voyage. However, dehydration and starvation then sometimes occurred as supplies of food and water ran out.

In the late eighteenth century causes of death were recorded in a number of broad categories based largely on the symptoms displayed. Fevers included general fever, malignant fever, nervous fever and yellow fever. Respiratory illnesses included inflammation of lungs, consumption and decline. Gastrointestinal diseases included flux, dysentery, diarrhea and worms. In addition a number of deaths were accounted for by accidents, mainly drowning, and suicide, mainly by jumping overboard. 

Figures about slavery and mortality collected at the time were used for a variety of reasons. In his 1789 speech opening the parliamentary debate on the slave trade William Wilberforce estimated that about 12.5 per cent of slaves transported died in the Middle Passage, 4.5 per cent died on western Atlantic shores before sale, and one third died in the process of acclimatising to the Americas. This is a total mortality of about 50 per cent, of which the Middle Passage accounted for about a quarter. It is estimated that of the roughly twelve million slaves who were despatched across the Atlantic, only around ten and a half million arrived alive.

Just as the point of embarkation could be anywhere within a few thousand miles, so could the point of disembarkation. The majority of slaves transported on British ships were delivered to the Caribbean islands of Jamaica, Barbados and Trinidad to work on the sugar plantations. Disability and disease were common amongst adult slaves in the Caribbean. Elephantiasis, transmitted by mosquitoes and resulting in swollen legs, was common in the sugar colonies. Many slaves suffered from dysentery, dropsy, fevers, and digestive and nervous diseases. Yaws, a non-venereal form of syphilis, was common, and there were regular epidemics, such as a cholera epidemic in Grenada in 1830.     

It has been estimated that as many as a third of newly arrived slaves died within the first three to four years of landfall. In 1788 Edward Long noted the prevalence of ‘epidemic and destructive distempers’ in Jamaica, amongst which he singled out smallpox, yaws and dysentery. Smallpox was a particular concern of plantation owners, and advertisements often made reference to slaves being clear of the disease. In fact, smallpox was the one disease brought under control in the early nineteenth century Caribbean. Vaccination and quarantine arrangements were used to contain outbreaks of the disease. Jamaica introduced a vaccination programme for its slaves in 1813, followed by Trinidad in 1819. But the range of diseases to which the slaves were subject meant that survival was a constant struggle.

Mortality and sickness amongst the crews were generally at similar levels to those of the slaves. A typical slave ship of between 100 and 200 tons would have a crew of between thirty and forty men. Off the African coast crew stayed on board their ships as far as possible, as interaction with the shore increased the crew’s exposure to infective mosquitoes. Many succumbed to malaria and yellow fever. Once at sea crew deaths from fevers peaked about twelve days into the voyage.

Treating sickness

Dealing with these diseases was an overwhelming challenge. There was little understanding of infectious diseases. European doctors still largely believed in miasmic theories, which held that diseaseswere the product of environmental factors such as contaminated water and foul air. But in the eighteenth century large numbers of surgeons were employed on ships. Some 500 people qualified as naval surgeons each year, and quite a number worked on slave ships. Naval surgeons had to anticipate the medical needs of both slaves and crew. Each surgeon had his own medicine chest.

Slave ships without a surgeon usually carried a medicine chest. Records survive of the contents of the chest of a ship without a surgeon trading off the African coast. The contents were deemed to be sufficient for a crew of twenty for one year. The internal preparations included a large amount of Peruvian bark, or cinchona, for malaria fever, and other powders, including rhubarb. The chest also contained opium and laudanum. There were large quantities of Epsom salts, gentian root and cream of tartar in the chest. The liquids included antimonial wine and castor oil. Large numbers of pills were also carried, including bilious and purging pills. Internal medicines were lettered for easy recognition.

A range of preparations was also available for external use. This included beeswax, simple ointments, extract of lead, red precipitate and ten pounds of flowers of sulphur. For the treatment of blisters there were plasters, and these could be made more effective by sprinkling powdered Spanish flies over the surface, pressing them well in with the finger. External medicines were also numbered for easy recognition, and the chests came with full instructions on how to treat what. A number of the items here clearly had an effect, like the Peruvian bark for malaria, and the opium for pain relief, but against the overwhelming onslaught of lethal tropical diseases the impact would have been marginal.

The abolition of slavery

Late in the eighteenth century groups of people on both sides of the Atlantic began expressing concern about the morality and justice of slavery and the sheer scale of the trade. The movement was led by Quakers, especially American Quakers in Philadelphia. In Britain, the campaign took off in 1786 when Thomas Clarkson wrote an Essay on ‘the Slavery and Commerce of the Human Species.’ The essay came to the attention of a new Yorkshire MP, William Wilberforce, who was asked by Pitt to lead the campaign against slavery. The first meeting of the Anti-Slavery Movement was held in 1787. Clarkson himself travelled the country addressing meetings of the movement. 

The campaign made full use of graphic images, most notably the one showing a cross-section of the slave ship Brookes, but there many others. Slave stowage plans continued to be published for a number of years, such as one for the slave ship Vigilante in 1823, held at the National Maritime Museum. In the 1790s a consumer boycott against sugar was mounted, with the Anti-Saccharine Society drawing attention to the miserable existence of slaves exploited on the sugar plantations. Further public support was raised using images of a slave with the slogan ‘Am I not a man and a brother?’

Other incidents assisted the campaign, such as the infamous Zongcase of 1783. The Zong was a Liverpool slaving vessel that had left West Africa heading to Jamaica, with 470 slaves on board in early September 1781. Outbreaks of disease amongst the captives spiralled out of control, and the captain decided to have 131 Africans thrown overboard. In 1783 the owners of the Zongapplied to their underwriters to claim maritime insurance for the loss of their cargo. The underwriters declined the claim, and the case went to court. The owners lost the case, but the scandal received widespread publicity, and the Quakers petitioned Parliament on the slave trade immediately afterwards.    

Following these events a number of initiatives were taken to improve the lot of the slave. Amongst them was Dolben’s Act, named after Sir William Dolben, the elderly MP for Oxford who had sponsored the legislation. Dolben’s Act of 1788 restricted the number of slaves that could be carried on British ships according to tonnage; the limit was five slaves for every three tons up to 200 tons, and one slave for every additional ton thereafter. So a ship of 210 tons could carry 350 slaves, and one of 260 tons could carry 400 slaves. The Act also stipulated that a surgeon should be present on all slaving voyages. They were also required to keep a log of all illnesses and deaths.

The Act abolishing the slave trade was passed in 1807. The last four legal British slave-ships to leave Africa sailed from the Sierra Leone River in October 1807. They carried some 1,100 Negroes in their holds, and were escorted by a Royal Navy frigate, in case enemy vessels attacked on sea-routes made unsafe by war. The Napoleonic wars were to carry on until 1815. This was the last time that British warships protected slavers. From January, their job would be to hunt them down.

The British West Africa Squadron

On 15 January 1808, HMS Derwentleft Freetown on the first Royal Naval cruise under the new arrangements. She headed north into the slaving waters of the River Pongas in Senegal. She checked all ‘strange sails,’ exchanged signals, boarded when ships stopped, and chased when they did not. Some weeks later, off Cape Verde, they stopped and detained two American schooners which were breaking their own country’s law by carrying 167 slaves. All three ships headed to Freetown, where these slaves, or ‘recaptives,’ became the first beneficiaries of the new British legislation. Many other actions followed. On 1 February 1829 the Black Jokecaptured the Spanish slaver Almirante,which was bound for Havana with 466 slaves on board. There was a ferocious fight, and the Black Jokewent on to capture a Brazilian slaver, Carolina. Between them the two actions released a total of 875 slaves.

Slaves in the Americas and Caribbean developed a range of strategies to oppose their oppression. All slave-holding societies experienced organized violent rebellions. The most successful was in the French colony of what is now Haiti in 1791. In 1795, a Britishfleet attempted to seize control of Haiti, but it suffered a heavy defeat, with 40,000 troops killed. Haiti became a Republic in 1804. Other rebellions included one in Barbados in 1816, a revolt in South Carolina in 1822, a slave rebellion in Demerara in Guyana in 1823, and one in Virginia in 1831. But an uprising in northern Jamaica in 1831-32 proved to be one of the most destructive in the British Caribbean. The rebel leader, Samuel Sharp, was a deacon in the Baptist Church, and it became known as the Baptist War.It began on 27 December 1831, whenrebel slaves starting destroying plantations. A painting held by the National Maritime Museum graphically illustrates the Destruction of the Boyne estates in the first few days.

In the 1830s Britain also had a West Indies Fleet, to protect British interests in the Caribbean. In practical terms this meant supporting the plantation owners, and assisting them in putting down the resurrection. The National Maritime Museumpossesses a painting showing boats from HMS Blancheattacking and capturing rebel positions near Montego Bay. HMS Blanchewas a 46-gun fifth rate warship originally launched in 1819. The riot involved some 20,000 people and caused damage of over £1 million. With the Navy’s help it was eventually put down. Some 200 slaves were killed, 312 including Sharp were executed after trials, and more than 300 others were imprisoned or transported.

Britain’s response to the continuing slave trade was strengthened in 1819. Sir George Collier was appointed commodore of a new naval force, the British West Africa Squadron, to patrol the trafficking routes and arrest ships involved in the trade. It was a difficult role; not only was he to suppress the illegal British slave trade, which was already diminishing fast; he was also expected to enforce Britain’s anti-slave trade treaties with other countries. Collier was provided with a flagship, HMS Tartar,and six other warships; HMS Thistle, HMS Pheasant, HMS Morgania, HMS Myrmidon, HMS Cherub and HMS Snapper. In the 50 years between 1820 and 1870, the Squadron stopped over 1,500 slave ships, and around 150,000 slaves were returned to Africa, mainly to Sierra Leone.

Although the trade itself was abolished in 1807, slavery itself continued for some years. The Emancipation Act was passed in 1833, but it only came into force 12 months later, on 31 July 1834. Slaves did not immediately gain their freedom; an apprenticeship scheme was introduced, which meant that they received minimal wages for another six years. When the apprentices were eventually freed in the British Caribbean after 4 years, in 1838, the only American territories where slavery had ended permanently were Chile, Mexico and Bolivia. Chile abolished slavery in 1823, Mexico in 1829 and Bolivia in 1831. Rio remained the hub for the South American slave trade for some time.

After emancipation it took another fifty years to see the end of the slave trade. America finally gave all slaves their freedom after the end of the American Civil War in 1865. The other powers with slaves in the Americas and Caribbean gradually freed them; slaves were freed in the Danish and French colonies in 1848 to 1849, and the Dutch abolished slavery in their colonies in 1863. Latin American countries were the last to hold out for slavery, but it was eventually abolished in Puerto Rico in 1873, in Cuba in 1886, and in Brazil in 1888.

During the course of its long history the extent of the slave trade fluctuated in line with wars, epidemics and demand. Although it never halted there were three periods of greater activity; from 1650 to 1683, from 1708 to 1725, and from 1746 to 1771; but it continued for another hundred years. By 1888 the formal Atlantic slave trade may have ended, but of course slavery, like piracy, continues to this day.

Further reading

Kenneth Morgan, Slavery and the British Empire: From Africa to America, Oxford: Oxford University Press, 2007.

Sian Rees, Sweet Water and Bitter: The ships that stopped the Slave trade, London: Chatto and Windus, 2009.

Michael Stammers, ‘Guineamen’: Some technical aspects of Slave ships, and David Richardson, Liverpool and the English Slave Trade, in Anthony Tibbles (ed.) Transatlantic Slavery: Against Human Dignity, Liverpool: Liverpool University Press, 1994.

Richard Sheridan, Doctors and Slaves: A Medical and Demographic History of Slavery in the British West Indies 1680-1834,Cambridge: Cambridge University Press, 1985.

James Walvin, A Short History of Slavery, London: Penguin Books, 2007.

This event was on Mon, 24 Oct 2011


Professor Stuart Anderson

The London School of Hygiene and Tropical Medicine

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