William Lyon Mackenzie was a Scottish Canadian-American journalist and politician. He founded newspapers critical of the Family Compact, a term used to identify elite members of Upper Canada. He represented York County in the Legislative Assembly of Upper Canada and aligned with Reformers. He led the rebels in the Upper Canada Rebellion; after its defeat, he unsuccessfully rallied American support for an invasion of Upper Canada as part of the Patriot War. Although popular for criticising government officials, he failed to implement most of his policy objectives. He is one of the most recognizable Reformers of the early 19th century.

York was a town and the second capital of the colony of Upper Canada. It is the predecessor to the old city of Toronto (1834–1998). It was established in 1793 by Lieutenant-Governor John Graves Simcoe as a "temporary" location for the capital of Upper Canada, while he made plans to build a capital near today's London, Ontario. Simcoe renamed the location York after Prince Frederick, Duke of York and Albany, George III's second son. Simcoe gave up his plan to build a capital at London, and York became the permanent capital of Upper Canada on February 1, 1796. That year Simcoe returned to Britain and was temporarily replaced by Peter Russell.