On June 22, 1772, Lord Mansfield, chief justice of the King’s Bench, handed down his famous decision that effectively eliminated slavery on the soil of the British Isles. Although slavery had gradually died out in Europe after the introduction of Christianity, it was not officially prohibited, and occasionally a slave owner from overseas would bring slaves with him to Britain. In his celebrated decision, Mansfield held that a slave automatically became a free man by setting foot in Britain. But this decision did not have the slightest effect on slavery in the overseas colonies.

Not until 1811 did William Wilberforce—who had been deeply influenced by John Newton, author of “Amazing Grace”—succeed in getting Parliament to ban the slave trade. In 1833 the decision was reached to abolish slavery throughout the British Empire over a six-year period.