The Triangular Trade System and the British Empire

The triangular trade was the most fully developed commercial system of the eighteenth-century British Empire, and the system that paid, in the Williams argument, for the British industrial revolution. The system was not, in the strict sense, a triangle. It was a network of three Atlantic trades — the British-to-Africa trade in manufactured goods, the Africa-to-Americas trade in enslaved Africans, and the Americas-to-Britain trade in colonial commodities — that was, in the eighteenth century, conducted by the same merchants, financed by the same credit, and insured by the same underwriters. Eric Williams’s Capitalism and Slavery (1944) made the case that the system was the foundation of the British industrial economy. Robin Blackburn’s The Making of New World Slavery (1997), David Eltis’s Atlantic History (1999), and the Trans-Atlantic Slave Trade Database at Emory have provided the empirical scaffolding on which the present generation of arguments rests.

The Structure of the System

The system had three principal legs. The “outward” leg ran from British ports to West Africa, carrying British manufactured goods — Lancashire cotton cloths, Yorkshire woollens, Birmingham firearms and metalware, Sheffield hardware, copper rods and bars, gin and rum, glass beads — to be exchanged for enslaved Africans. The “middle passage” carried the enslaved Africans across the Atlantic to the British Caribbean and the British North American colonies. The “homeward” leg carried colonial commodities — sugar, tobacco, rum, cotton, indigo, ginger, coffee, and cocoa — back to British ports, where they were sold in British markets, re-exported to Europe, or refined and re-exported.

The system was, in formal terms, three interlocking trades. In practice, it was a single integrated commercial system in which the same Liverpool, Bristol, and London merchant houses operated on all three legs, the same Bristol and Liverpool shipowners built the vessels, and the same London and Liverpool underwriters insured the cargo. The Royal African Company, chartered in 1672, and the Company of Royal Adventurers Trading into Africa (which had preceded it) operated on the outward leg under the formal monopoly of the Crown. The 1698 Act for the More Easy Recovery of Debts in Africa and Elsewhere opened the trade to all British subjects, and the 1750 abolition of the Royal African Company’s monopoly confirmed the de facto openness. The triangular trade, in its mature form, was a private-enterprise system under the political protection of the British state.

The Manufactured Goods Trade

The British manufactured goods trade with West Africa was, in the late seventeenth and early eighteenth centuries, the principal external market for the British metalware, textile, and firearms industries. The Birmingham gun trade produced, by 1800, perhaps 40 per cent of the long guns sold in West Africa; the Sheffield hardware trade produced the brass pans, the iron bars, the copper rods, and the manillas that were the principal currency articles of the West African trade; the Lancashire cotton trade produced the “guineas” — the cheap printed cotton cloths — that were the principal article of trade at the Gold Coast. The gin and rum trades produced the alcohol that the British and West African merchants used to balance the trade.

The economic history of the British manufactured goods trade is, in Joseph Inikori’s Africans and the Industrial Revolution in England (2002), the case for the central importance of the Atlantic slave trade to British industrialisation. The argument is that the West African market absorbed a substantial fraction of the British output of the metalware, textile, and firearms industries in the period 1690–1807, and that the demand from the West African trade was, in turn, one of the principal stimuli to the technical innovations of the period. The argument is contested. The economic historian Patrick O’Brien has argued that the Atlantic trade was, in proportional terms, a small share of the British economy by 1800, and that the role of the trade in the British industrialisation is, at most, a second-order question. The present consensus is that the trade was important to specific industries — Birmingham firearms, Bristol copper, Lancashire cotton — without being central to the British economy as a whole.

The Middle Passage

The Middle Passage — the transatlantic voyage from West Africa to the Americas — was the central feature of the triangular trade, and the most heavily documented. The Trans-Atlantic Slave Trade Database, established at Emory in 2008, has identified some 36,000 slave-trading voyages, of which the British slaving voyages account for roughly 12,500, transporting 3.4 million Africans to the Americas between 1662 and 1807. The British slave trade was, by the 1780s, the largest single national component of the Atlantic trade. The mortality rates on the British Middle Passage averaged some 15 per cent on the West African routes and 10 per cent on the West Indian routes; the rate was higher on the smaller British slavers of the 1680s and 1690s, and lower on the larger, faster, and more carefully crewed British slavers of the 1790s.

The social history of the Middle Passage is the subject of Marcus Rediker’s The Slave Ship: A Human History (2007) and the sources collected in the Many Thousands volume edited by Charles van Onselen. The evidence is drawn from the surviving surgeons’ logs, the ship captains’ logs, the insurance records, the abolitionist interviews, and the oral traditions of the West African and West Indian communities descended from the survivors. The accounts converge on a consistent picture: the Middle Passage was a sustained exercise in organised violence, in which the British and West African merchants, the British ship captains, and the British ship crews extracted labour from human cargoes under conditions in which a substantial fraction of the cargoes died. The system was, in this sense, a system of violence by design.

The Colonial Commodities Trade

The homeward leg of the triangular trade carried the colonial commodities — sugar, tobacco, rum, cotton, indigo — to the British and European markets. Sugar was the principal British Caribbean commodity; the 18th century saw a rapid expansion of the British Caribbean sugar production, from 25,000 tons in 1700 to 95,000 tons in 1775. Tobacco was the principal British North American commodity, exported through the great Virginia and Maryland plantations. Rum, distilled from the byproducts of the Caribbean sugar production, was the principal British West Indian alcohol export, and the principal article in the West African trade. Cotton, exported from the British North American colonies from the 1780s, was the principal British industrial raw material; the British cotton industry was, in 1800, the largest single industry in the world. Indigo, produced in the British Caribbean and British India, was the principal British dyestuff.

The economic effect of the colonial commodities trade was, in Williams’s argument, the conversion of the British economy into a processing and re-exporting economy in which the raw materials were imported from the British colonies, the manufactured goods were produced in British factories, and the surplus was re-exported to Europe and the world. The argument is the foundation of the Williams thesis. The economic historian John J. McCusker and Russell R. Menard have argued, in The Economy of British America, 1607–1789 (1985), that the British colonial trade was, in fact, a larger share of the British economy than the Williams argument implies, and that the role of the trade in the British industrialisation is, accordingly, larger.

The Campaign Against the Trade

The 1807 Slave Trade Act received the Royal Assent on 25 March 1807 and took effect on 1 May 1807. The Act prohibited the British slave trade throughout the British Empire, and it made the slave trade a felony for British subjects. The preamble is the founding document of the British humanitarian tradition: “Whereas the African Slave Trade is contrary to the Principles of Justice, Humanity, and sound Policy, and is highly dishonourable to the British Crown, and a proper Subject for the Consideration of Parliament: Be it therefore enacted by the King’s most Excellent Majesty, by and with the Advice and Consent of the Lords Spiritual and Temporal, and Commons, in this present Parliament assembled, and by the Authority of the same, That from and after the First Day of May One thousand eight hundred and seven, the African Slave Trade shall be, and the same is hereby utterly abolished, prohibited, and declared to be unlawful.” The 1833 Abolition of Slavery Act, which took effect on 1 August 1834, abolished slavery itself in the British Empire. The 1833 Act was, in the structure of the triangular trade, the moment the system was dismantled.

The campaign against the British slave trade was, in the British historiography, the work of three overlapping coalitions. The 1787 Committee for the Abolition of the Slave Trade, led by Thomas Clarkson and Granville Sharp, included nine evangelical Anglican MPs led by William Wilberforce. The 1791 Quaker petition against the slave trade, the 1792 mass petition campaign, and the 1807 mass petition campaign produced the political conditions for the 1807 vote. The 1815 Congress of Vienna, the 1818 Anglo-Dutch slave trade treaty, the 1842 Quintuple Treaty, and the 1890 Brussels Convention were the international conditions of the abolition. The campaign is the subject of Hugh Thomas’s The Slave Trade (1997), of Robin Blackburn’s The Overthrow of Colonial Slavery, 1776–1848 (1988), and of the more recent work of Christer Petley and others.

The Decolonisation of the Trade

The 1860s suppression of the Brazilian slave trade, the 1885 Berlin Conference, the 1890 Brussels Convention, and the 1926 Slavery Convention completed the international abolition. The 1948 Universal Declaration of Human Rights, the 1956 Supplementary Convention on the Abolition of Slavery, and the 2014 estimated 36 million people in modern slavery are the post-imperial conditions. The economic historian Kevin Bales, in Disposable People (1999) and The Slave Trade in the Digital Age (2021), and the historian of slavery David Eltis have produced the modern history.

Historiographical Note

The historiography of the British triangular trade has been transformed, since the 1940s, by three rounds of work. Eric Williams’s Capitalism and Slavery (1944) framed the question in terms of the relationship between the slave trade and British industrialisation. Hugh Thomas’s The Slave Trade (1997) and Robin Blackburn’s The Making of New World Slavery (1997) provided the narrative and the analytical scaffolding. The Trans-Atlantic Slave Trade Database, established at Emory in 2008, has provided the empirical base on which the present generation of arguments rests. The unresolved question is the weight to assign to economic interest and to moral sentiment in the abolition of 1807. The present generation of historians has, on the whole, declined to give the British Empire’s commercial legacy a clean bill of health.

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