Asiento of 1713: Britain's Slave-Trade Contract with Spain

The Asiento of 1713 was a contract that gave Great Britain, for thirty years, the exclusive right to supply enslaved Africans to Spain’s American colonies. Granted by Philip V of Spain as part of the peace settlement that ended the War of the Spanish Succession, it was handed to the South Sea Company. The contract shaped British dreams of riches in Spanish America, helped inflate the South Sea Bubble of 1720, and fed the quarrels that led to the War of Jenkins’ Ear.

Background: what was an asiento?

An asiento was a Spanish government contract. The asiento de negros licensed a private merchant, company or foreign power to deliver enslaved Africans to Spanish America. Under a papal division of the world and the Treaty of Tordesillas, Spain had no trading posts in West Africa, so for nearly two centuries it relied on others, at different times Genoese, Portuguese, Dutch and French contractors.

The contract was valuable for more than the slave trade itself. Spain normally kept foreigners out of its colonial markets, and an asiento gave the holder ships, agents and warehouses inside the Spanish empire. This created many opportunities for smuggling.

When the Bourbon prince Philip of Anjou became Philip V of Spain in 1700, he gave the asiento to the French Royal Guinea Company in 1701. Britain and its allies fought the War of the Spanish Succession partly to stop France from dominating Spanish trade, and the asiento became one of the prizes of the peace.

The terms of 1713

British and Spanish negotiators signed the asiento treaty in Madrid on 26 March 1713, and it was confirmed in the Anglo-Spanish peace treaty of 13 July 1713, part of the wider Treaty of Utrecht. Its main terms were:

• For thirty years from 1 May 1713, Britain would deliver 144,000 “piezas de Indias”, about 4,800 a year. A pieza was a unit of account for a healthy adult; children and older people counted as fractions, so the actual number of people could be higher.
• The contractor would pay the Spanish crown a duty of 33⅓ pesos per pieza, with an advance payment.
• The kings of Spain and Britain were each entitled to a quarter of the profits.
• In addition, Britain could send one “annual ship” (navío de permiso) of up to 500 tons each year to sell goods at the great colonial fairs at Portobelo or Veracruz.

The British government transferred the contract to the South Sea Company, which Robert Harley’s ministry had created in 1711. The company had taken over about £9 million of government debt in exchange for a monopoly on British trade with Spanish America, and the asiento gave that monopoly real substance.

How the trade worked

The South Sea Company did not at first operate its own forts in Africa. It bought many captives from British traders, including at times the Royal African Company, and shipped them to Jamaica and Barbados, where they were often resold or re-shipped to Spanish ports. The company placed “factors” (agents) in Cartagena, Portobelo, Panama, Veracruz, Havana, Caracas and Buenos Aires.

The crossing itself followed the brutal pattern of the Middle Passage: crowded holds, disease and high mortality, followed by sale and forced labour on plantations, in mines and in households across Spanish America.

The company never came close to filling its quota. Historians’ estimates of the number of people it delivered vary, but all fall far below the 144,000 piezas allowed, generally in the tens of thousands. The annual ship sailed only a handful of times between 1717 and the early 1730s, although company vessels were widely accused of carrying far more goods than permitted.

Smuggling and the annual ship

For many British merchants the real attraction of the asiento was not the slave trade but access to Spanish American markets. Spain’s colonial system was designed to keep trade in Spanish hands, funnelling goods through official fleets and fairs. The asiento opened a legal door, and smugglers used it widely.

Company ships carrying enslaved people were often accused of bringing extra goods, such as textiles, which were sold illegally alongside them. The annual ship was said to be restocked at sea from smaller vessels so that it could sell far more than its permitted 500 tons. Spanish officials, for their part, were often willing to take bribes. These practices angered the Spanish crown and fed a growing belief in Madrid that the British were exploiting the treaty.

At the same time, independent British traders based in Jamaica carried on a large illegal trade of their own along the Spanish Main, outside the company’s control. This made it hard for Spanish coast guards to distinguish between legitimate asiento business and simple contraband.

Who profited?

The asiento’s financial record was poor. The company faced heavy costs, high mortality among the captives, frequent seizures during wars and disputes with Spanish officials over duties and accounts. Many historians conclude that the trade made little or no overall profit. Its main beneficiaries were individual agents, ship captains and smugglers, and the Jamaican merchants who sold captives on to the company.

War, the Bubble and Jenkins’ ear

The asiento was repeatedly disrupted by conflict. During wars with Spain in 1718–1720 and 1727–1729, Spanish authorities seized company property and halted the trade.

The asiento also played a part in the South Sea Bubble. In 1719–1720 the company offered to take over most of the national debt in exchange for new shares. Promoters talked up the riches of the South American trade, and share prices soared from about £128 in January 1720 to around £1,000 in the summer before collapsing in the autumn. In reality the asiento trade earned little.

Friction continued in the 1730s. Spanish coast-guard ships (guarda costas) stopped British vessels suspected of smuggling. In 1731 a guarda costa captain cut off the ear of Robert Jenkins, master of the brig Rebecca. In 1738 Jenkins reportedly showed the ear to the House of Commons, and the story became a symbol of Spanish “outrages”. Disputes over the asiento, including Spanish claims against the company, helped wreck the Convention of Pardo of January 1739, and Britain declared war in October 1739. The conflict became known as the War of Jenkins’ Ear and merged into the War of the Austrian Succession.

The end of the asiento

The Treaty of Aix-la-Chapelle of 1748 restored the asiento for the four years lost to war. But neither side wanted it to continue. Under the Treaty of Madrid of 5 October 1750, Britain gave up its remaining rights in return for £100,000 paid to the South Sea Company. Spain later moved away from asientos and, from the 1780s, opened the slave trade to its colonies more widely.

By the numbers

Timeline

• 1701: Philip V grants the asiento to the French Royal Guinea Company.
• 1711: The South Sea Company is founded in London.
• 1713, 26 March: The Anglo-Spanish asiento treaty is signed in Madrid.
• 1713, 13 July: The Anglo-Spanish peace treaty at Utrecht confirms it.
• 1717: The first annual ship sails for the Spanish American fairs.
• 1720: The South Sea Bubble inflates and collapses.
• 1739, October: Britain declares war on Spain (War of Jenkins’ Ear).
• 1750, 5 October: Treaty of Madrid ends the British asiento for £100,000.

Why it matters

The Asiento of 1713 shows how deeply the trade in enslaved Africans was woven into European diplomacy and finance. A clause in a peace treaty turned human beings into units of account, launched a speculative mania in London and helped drag Britain and Spain back into war.