The Atlantic slave trade

How did the Atlantic trade begin?
It was pioneered by the Portuguese, the first Europeans to navigate the length of West Africa. From the 1440s, they sold African slaves in Portugal, and in the course of that century they settled a series of uninhabited islands off West Africa – São Tomé and Príncipe, the Cape Verde Islands, Madeira – and found them ideal for the cultivation of sugar, a scarce and lucrative commodity at the time largely grown in the Holy Land. A formula was established on the Atlantic islands: sugar meant large plantations; plantations meant African slaves. Sugar was first planted in the New World by the Spanish in Jamaica around 1513, using coerced indigenous Taíno workers. But like the Portuguese who colonised coastal Brazil in the 1530s, they found the local labourers ran away and succumbed all too easily to Western diseases. Portuguese slave-traders filled the gap: by 1600, some 200,000 Africans had been shipped across the Atlantic.

When did Britain become involved?
Over three centuries, Atlantic slavery fed a vast economic system reaching across the Americas, driven by sugar, but including other export crops such as tobacco, coffee, rice and cotton; slaves also worked in industries from mining to domestic service. More than 12 million Africans were shipped across the ocean (some 10.5 million survived the journey), mostly by Portuguese, British, French, Spanish, Dutch and Danish slavers. English ships made their first slaving raids in the mid-1500s, but the process began in earnest with the seizure of Barbados and Jamaica a century later: British merchants shipped more than three million people overall. Again, labour-intensive sugar was the great driver: slaves had soon replaced convicts and indentured servants in the cane fields. By the mid-1700s, writes James Walvin in A Short History of Slavery, “the British had emerged as the commercial and maritime masters of the bleak skills of moving large numbers of Africans speedily and profitably towards the American plantations”.

How economically significant was slavery to Britain?
Vastly. From the 1740s to the 1820s, sugar was the nation’s most valuable import. Bristol, Liverpool and the City of London thrived on the “triangular trade”, whereby goods such as copper, cloth and guns were traded with local slavers on the coast of West Africa for slaves, who were taken on the “middle passage” to the Caribbean; finally, ships returned to Europe carrying such slave-produced goods as sugar, molasses, rum and coffee. It is hard to judge precisely the contribution slavery made to Britain’s growing economy, as it coincided with the industrial revolution and the expansion of empire. But one recent study, by Klas Rönnbäck of the University of Gothenburg, suggests that by 1800, slave-related industries contributed about 11.1% of Britain’s GDP. Many institutions, including the Bank of England, Lloyds of London, Barclays bank and the Church of England, were heavily involved.

Who pushed for its abolition?
There had long been moral doubts about slavery. The Quakers had argued that it was un-Christian since the 1670s, and in a famous case of 1772, Chief Justice Lord Mansfield deemed it “odious” and without basis in English law. Around the same time, non-conformist missionaries began converting and advocating for West Indian slaves, while Enlightenment thinkers criticised slavery for violating the rights of man. From the 1780s, abolitionism became a very popular cause in Britain, thanks to campaigners such as William Wilberforce MP and the indefatigable pamphleteer Thomas Clarkson, who over 50 years travelled more than 30,000 miles to speak and gather evidence against slavery.

What sort of evidence did the abolitionists gather?
They published “slave narratives” by former slaves like Olaudah Equiano, a prominent figure in the abolitionist movement, and the testimony of those who’d served on slave ships and described their horrors. In 1781, an incident in which more than 130 Africans were thrown overboard due to water shortages became a cause célèbre: the verdict in the subsequent insurance dispute, the Zong case, was that it was legal to murder slaves in some circumstances. More influential still was the 1787 publication of the diagrams of the Brookes slave ship, showing 454 Africans packed into spaces just ten inches high. Such conditions led not just to mutinies and suicides, but high levels of infection and dysentery – the “bloody flux”. Other ships could smell slave ships several miles downwind.

How was the slave trade abolished?
The Slave Trade Act of 1807 – the culmination of nearly 20 years of parliamentary campaigning led by Wilberforce – ended the British trade. The last legal slave ship, Kitty’s Amelia, left Liverpool for Sierra Leone on 27 July that year. The Act was a compromise; slavery itself survived. Abolitionists hoped it would force planters to treat slaves better, since they would not be able to replace them; before then, up to 40% died within three years of arrival. They also hoped it would lead to the end of slavery altogether, but progress was slow.

Why was slavery abolished?
In the 1820s and 1830s, West Indian planters found themselves facing a large, articulate opposition made up disproportionately of nonconformists and women. It had become clear that slavery could not be reformed, and could only be maintained using great violence: after the slave rebellion in Jamaica in 1831-2, more than 300 slaves were executed. But economic self-interest played a major role too. Sugar could by then be grown more cheaply by waged labourers in India; slavery was seen as both wrong and uneconomic. Even so, human lives had to be balanced against property rights – and when the Slavery Abolition Act of 1833 finally passed, it was the 46,000 slave-owners, not the slaves, who were compensated, with a total of £20m (£17bn in today’s money).