During the late 18th century, an influential segment of the British public actively advocated for the abolition of slavery across the British Empire. Their actions and initiatives played an important role in Britain's 1807 decision to abolish the transatlantic slave trade and the outright abolishment of slavery across the Empire in 1834. It was also during this time that the first steps were taken toward the abolition of slavery in what is now Ontario. An act of resistance by an enslaved Black woman in Queenston led to the first anti-slavery legislation in the province – as well as the whole British Empire. Chloe Cooley's violent resistance to being forcibly transported across the river to a new owner in the United States drew the attention of free Black veteran Peter Martin, and a neighbour and witness to the event, William Grisly. Together, they compelled Lieutenant Governor Simcoe to put an end to slavery in Upper Canada.
In response, Simcoe took the first legislative step toward the abolition of slavery in Upper Canada. His 1793 "Act to prevent the further introduction of slaves and to limit the term of contract for servitude within this province" prohibited the importation of slaves into Upper Canada. Any slaves already living in the province at the time of this law's enactment, however, remained the property of their owners, as did their children until they reached the age of 25. This act set the stage for the abolition of the transatlantic slave trade by Britain in 1807 and the outright abolition of slavery across the British Empire on August 1, 1834. To this day, Emancipation Day celebrations continue across the province at the beginning of August.
As in Britain, public pressure in Upper Canada also played an important role in the movement to abolish slavery across the British Empire. Religious organizations such as the Methodist Church organized movements to advocate for the abolition of slavery on moral grounds. They felt that treating Blacks as property was un-Christian and their vocal advocacy helped to inspire Simcoe and his fellow legislators to act against slavery.