Throughout the growth of slavery in the American South, Nova Scotia became a destination for black refugees leaving Southern Colonies and United States via the Underground Railroad. While many blacks who arrived in Nova Scotia during the American Revolution were free, others were not. Black slaves also arrived in Nova Scotia as the property of White American Loyalists. In 1772, prior to the American Revolution, Britain outlawed the slave trade in the British Isles followed by the Knight v. Wedderburn decision in Scotland in 1778. This decision, in turn, influenced the colony of Nova Scotia. In 1788, abolitionist James Drummond MacGregor from Pictou published the first anti-slavery literature in Canada and began purchasing slaves' freedom and chastising his colleagues in the Presbyterian church who owned slaves. In 1790 John Burbidge freed his slaves. Led by Richard John Uniacke, in 1787, 1789 and again on 11 January 1808, the Nova Scotian legislature refused to legalize slavery. Two chief justices, Thomas Andrew Lumisden Strange (1790–1796) and Sampson Salter Blowers (1797–1832) were instrumental in freeing slaves from their owners in Nova Scotia. They were held in high regard in the colony. By the end of the War of 1812 and the arrival of the Black Refugees, there were few slaves left in Nova Scotia. The Slave Trade Act outlawed the slave trade in the British Empire in 1807 and the Slavery Abolition Act of 1833 outlawed slavery all together. With slaves escaping to New York and New England, legislation for gradual emancipation was passed in Upper Canada (1793) and Lower Canada (1803). In Upper Canada the Assembly ruled that no slaves could be imported; slaves already in the province would remain enslaved until death, no new slaves could be brought into Upper Canada, and children born to female slaves would be slaves but must be freed at the age of 25. Under the auspices of John Graves Simcoe, the Act Against Slavery of 1793 was legislated, and was the first legislation passed opposing slavery in the British Empire. In practice however, some slaves continued to live in bondage until abolished in the entire British Empire in the 1830s. The historian James M. McPherson defines an abolitionist "as one who before the Civil War had agitated for the immediate, unconditional, and total abolition of slavery in the United States". He does not include antislavery activists such as Abraham Lincoln or the Republican Party, which called for the gradual ending of slavery.