The influence of Enlightenment thinkers also played a role. The illustration below, from Voltaire's popular work Candide, shows Candide and his companion Cacambo encountering a slave who has had his hand destroyed in a mill and leg cut off for running away. The slave tells them, "This is the price of your eating sugar in Europe."
In the 1780's, the innovative potter Josiah Wedgwood, Darwin's grandfather, produced the famous medallion below on behalf of the movement to end the slave trade.
The image below, of "tight packing" aboard the slave ship Brookes, was published in Plymouth, England in 1788 and soon became an icon of the antislavery movement.
The painting below, by JMW Turner (1840), depicts the infamous case of the slave ship Zong , AKA the Zong Incident or Zong Massacre (1783).
When the ship ran low on water, the captain of the Zong ordered more than 100 Africans thrown overboard in order to save the rest. The captain claimed insurance on the "lost cargo." In a famous court case, Lord Chief Justice Mansfield (pictured below), who had effectively declared slavery illegal under English law in 1772, denied the insurance claim though many people thought the captain and his henchmen should have been tried for murder.
The shocking nature of the Zong Massacre galvanized opponents of the slave trade, who mounted a mass popular movement to end it. The trade was abolished by Parliament in 1807. Abolition of slavery itself in the empire followed in 1833, but the peculiar institution survived for decades in many parts of the globe. Turner's painting was painted in 1840 for the International Conference on Abolition of Slavery held in London, testimony to the enduring power of the Zong Incident.