A brief guide to the transatlantic slave trade

On their tentative explorations of the African coast in the 15th century, Europe’s emergent maritime powers, led by the Portuguese, found sources of gold and of slave labour, both bought and exchanged from African traders. Their initial trade in slaves developed between different African societies. But a hostile environment, and especially disease, prevented Europeans (with a few notable exceptions) establishing settlements in Africa. Meanwhile, in Europe’s American settlements, they needed labour, particularly following the massive decline of Indian populations (due, again, to disease). Europe’s maritime technology and the availability of slave labour in Africa came together into a profitable trade, with slaves transported in growing numbers across the Atlantic. The slave ships concentrated on African societies familiar with slavery (in the form of women, prisoners of war or criminals) and which, to satisfy the demand from the slave ships, could extend their search for victims further into the interior. The flow of Africans to the coast was thus as much a consequence of internal – and often violent – African factors as it was of demand from the American plantations. But the stimulus of the presence of the slave ships became vital.

This trade began before Columbus crossed the Atlantic, with enslaved Africans shipped between African coastal societies, to the Atlantic islands and on to Europe (notably to Portugal). The early transatlantic voyages, with slaves collected mainly via piratical raids, went to Spain's Caribbean colonies, where the captives were largely used for gold-mining. All of this changed when the Portuguese developed slave-based sugar plantations. After perfecting it on the islands of São Tomé and Príncipe in the Gulf of Guinea, the Portuguese shifted sugar cultivation – along with African slaves – to Brazil by the late 16th century. It prompted the growth of European demand for sweet food and drink.

The early piratical trade for slaves evolved into a formal, regulated business, with slave ships carrying valuable cargoes to Africa to exchange for slaves. Commodities from different parts of the world were exchanged for enslaved people. They, in turn, were shipped across the Atlantic. Slave-ship captains were important players: master-mariners and managers of generally difficult crews, they were key traders on the African coast. They offered a huge range of goods to tempt African traders to part with their slaves: textiles, guns, French wines and Caribbean rum, cowrie shells and tobacco. Thereafter, they became the head jailors on floating prisons packed with dangerous and defiant Africans.

Huge numbers of Africans began to land, first in Brazil and then in the French and British islands in the Caribbean, and in much smaller numbers in North America. By the end of the 17th century, up to 30,000 Africans were being transported annually. A century later, those numbers had almost tripled. Between 1642 and 1800, Dutch, British and French slave ships had carried more than 5 million Africans to the New World. Another 2 million followed in the half century to 1850.

The Atlantic slave trade became the largest enforced movement of humanity ever recorded. It attracted all the maritime nations of both Europe and the Americas. Ships headed to Africa from 188 ports, almost half of them in America. Few ports could resist the commercial lure of the slave trade, and some (such as Bristol and Bordeaux) rose to civic and commercial eminence as a result of it. But the trade was dominated by a small band of ports. Ships from Rio, Salvador and Liverpool each carried more than a million Africans; Havana ships carried 683,000. The slave ships and their cargoes were backed by local financial and commercial interests, and by funders from a wide hinterland.

The labour of enslaved Africans drove the growth of economies across the Americas. Though based largely in tropical and semi-tropical work, slavery crept into all corners of the economies. Slaves worked as domestics, skilled workers, sailors and cowboys. Despite this, all of Europe’s major slave empires, and the independent nations that emerged from the collapse of those empires, continued to view the slaves as ‘chattel’: objects of trade to be bought and sold, bartered and bequeathed, inherited and given away.

For some years, the slave trade was organised through national monopoly companies (designed to exclude other nations) but voracious American demand led to a more open trade. Slaving thus became an area of international competition, friction and colonial rivalries – whose effects can be witnessed in the shape of Africa’s massive coastal slave forts. Visited today by waves of tourists, these strongholds were once grim prisons for Africans about to be forced onto the ships. But many others embarked from different locations: from baracoons or simple beaches.

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Although the Atlantic trade is seen in the popular mind as triangular, it was more complex and varied than that. Prevailing currents and winds created two trading systems. The one in the north Atlantic (dominated eventually by the British) was slower and therefore most costly of lives. The other, in the south Atlantic, provided faster transit times and was dominated by Portugal and Brazil. These two separate, though somewhat overlapping, systems ensured that Africans from particular regions were fed into the different American locations. As the slave trade evolved, however, routes developed between all points of the Atlantic compass, with vessels criss-crossing the Atlantic between Europe, Africa and the Americas. It became a vast market in African humanity, enabling American plantations to disgorge ever greater volumes of tropical produce for western consumers. In the process, commodities that were initially luxuries, such as sugar and tobacco, became the cheap everyday habits of people everywhere.

Although the Atlantic trade is seen in the popular mind as triangular, it was more complex and varied than that

The damage to Africa was enormous, though unevenly spread. Slave trading waxed and waned over time and from one region to another; some areas remained relatively untouched by it. Enslaved people arrived on Africa’s Atlantic coast in response to upheavals and trade in the interior. By the late 18th century, slaves were being loaded at many points along the Atlantic coast, though the most active stretch of the trade was located between Cape Lopez (in modern Gabon) and Benguela (Angola). In the century to 1850, almost half of all Africans shipped to the Americas embarked from there. In fact, most Africans departed from a small number of ports: two-thirds from a mere 10 African locations. Almost 3 million left from Luanda in Angola, while more than 1 million went from Ouidah in modern Benin and 764,000 from Benguela.

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They sailed westwards in a great variety of ships. We know of small vessels capable of carrying only a handful of slaves. At its peak however, the trade was characterised by large vessels ferrying upwards of 500 Africans. The Brookes (the most famous ship of all) – was 207 tons. On 10 voyages from Liverpool she transported 5,163 Africans (of whom 4,559 survived). Pictures of that ship – reprinted time and again today (see image below) – have helped to secure the Brookes a place in popular memory.

From the early days, slave traders realised that overcrowding was dangerous, and slave trading nations tried to regulate it. Such regulations were often disregarded by avaricious traders – especially during the ‘illicit’ trade of the 19th century, when grossly overcrowded vessels, seeking a quick run to Brazil or Cuba to evade the US and British abolitionist navies, recorded some of the most appalling levels of death and suffering.

Africans entered the ship stripped of everything: their clothing, their names, their families and friends. They were totally deracinated and, not surprisingly, from first to last, the slave ships simmered with defiance. Many tried to escape en route to the coast, and resistance thrived on board the pestilential vessels. Vessels filled slowly with other captives, and many of them spent longer on the ship anchored off the African coast than they did on the Atlantic crossing.

Sailors had to be permanently alert: a careless move, slipshod handling of tools, inattention – all and more could (and often did) lead to slave violence. One in 10 ships experienced some form of slave revolt, with Africans from certain regions more likely to revolt than others. Slave traders thus became cautious of where they traded and who they purchased. The crew always needed chains and shackles to secure their human cargoes, who greatly outnumbered them on all slave voyages.

The Atlantic crossing was a brutal experience for every African, and all learned the lesson of what would happen to those who openly resisted. The bitter memories of those seaborne sufferings were carried into the Americas. Yet despite the commonplace cruelty and widespread fatalities, the aim of the slave traders was to deliver slaves to American buyers. Traders did not seek to kill or harm the slaves, but rather to keep them alive and fit for sale at landfall. The fact that so many died, or arrived in a miserable condition, should not deceive us. The intention was to make a profit on the voyage – and that meant keeping slaves alive and well. However, often this was not possible, and shipboard conditions deteriorated. Bad weather, poor supplies, brutal sailors (with their own serious levels of mortality), disease – all these and more wreaked havoc among the incarcerated Africans. The suffering on the slave ships was uniquely horrible, and left its physical and mental scars on all who survived.

The Atlantic crossing was a brutal experience for every African

Although the average crossing took two months, voyages could be prolonged by bad weather, navigational errors and poor management. In time, experience, better ships and more efficient navigation hastened the voyages, but the Atlantic crossing still remained hazardous for all on board. However prolonged or swift, the middle passage entailed human misery on an incomprehensible scale, and its horrors proved influential in the rise of abolitionism. In the late 18th century, details from the slave ships, broadcast to an expanding reading public, appalled people on both sides of the Atlantic. It sparked the first phase of the campaign to end the trade.

The road to abolition

In the last quarter of the 18th century, the slave trade found itself under growing attack. Yet this was a time when slave prices were high and when traders felt their business was lively and profitable. Early objections emerged from the French and Scottish Enlightenment, but perhaps even more influential was the rising influence of Dissenters – led by Quakers on both sides of the Atlantic. These early abolitionists, working through chapels and public meetings, exposed the brutal realities of the slave ships, helped by cheap print and popular literacy. The campaign was also aided by the voices of Africans – most of them ex-slaves – who lent a powerful personal testimony to the cause, and were crucial in tipping the balance.

The ideals of liberation first unleashed by the American War of Independence (ironically led by a cabal of slave owners) were enhanced by the upheavals in France and her colonies after 1789. The question – obvious to slave and free alike – was: did the principle 'liberty, equality, fraternity' apply only to white people? After 1791, the apocalyptic violence in the French colony of Saint-Domingue (Haiti after 1804) sent tremors throughout the enslaved Americas. It inspired slaves and terrified slave owners. The Haitian revolution, and the protracted warfare between France and Britain, silenced the early demands for an end to the slave trade. A change of government and ministers, plus a reemergence of anti-slave trade sentiment, revived the cause, and both Britain (1807) and the United States (1808) finally ended their slave trades; the Danes had been first in 1802. By then, the US no longer needed imported Africans because North America's slave population was expanding and provided enough slaves for local use. But it was surprising that the British ended their trade when many involved – traders and planters – continued to demand ever more Africans. The British abolition seemingly flew in the face of the nation's economic self-interest.

Thereafter, a series of treaties authorised the British and US navies to stop the slave ships, though huge numbers of Africans continued to cross the Atlantic, largely because of demand from Cuba and Brazil. Following the 1807–08 abolitions, some 2,000 vessels were stopped and 125,000 Africans released, but the trade was not seriously hindered until the 1840s and 1850s, when Cuba and Brazil finally acted against it. Transported mainly in Spanish, Portuguese and Brazilian ships, more than 3 million enslaved Africans were landed in the Americas in the 19th century.

The Atlantic crossing remains perhaps the best-known passage for slaves, but there were other enormous slave routes that scattered Africans and their descendants across great distances. Over the course of a millennium, huge numbers of Africans were forcibly marched across the Sahara to the slave markets of north Africa. Other routes saw captives moved eastwards, to the slave markets of east Africa, and thence to Arabia and to India. Meanwhile, for those crossing the Atlantic, landfall did not bring an end to their enforced travels. After landing, they were moved onwards, to inland settlements and properties: to the North American backcountry, to remote plantations in Caribbean valleys and mountains, and deep into the vastness of South America – even high into the mining districts of the Andes.

Slaves in the Americas could never feel secure, never certain that they would not be uprooted and moved on yet again: re-sold, bequeathed, inherited; relocated with the movement of owners, or through the misfortunes of economic upheaval or warfare. After 1800, the US cotton industry drew slave labour south and west from the old slave states. Almost a million people were uprooted in this way. One slave family in five was wrecked in the process, and one slave child in three was torn from its parents. At the same time, an internal slave trade in Brazil was even larger – forcibly moving people from old regions to newly opened industries (notably coffee). Long after the Atlantic slave trade had ceased, the buying and selling of human beings continued to blight the lives of millions.

James Walvin is professor emeritus of history at the University of York and author of The Slave Trade (Thames & Hudson, 2011) and Freedom: The Overthrow of the Slave Empires (Robinson, 2019).

This article was first published in the November 2019 issue of BBC History Magazine