<P> Mackenzie, Duncombe, John Rolph and 200 supporters fled to Navy Island in the Niagara River, where they declared themselves the Republic of Canada on December 13 . They obtained supplies from supporters in the United States, resulting in British reprisals (see Caroline affair). On January 13, 1838, under attack by British armaments, the rebels fled . Mackenzie went to the United States where he was arrested and charged under the Neutrality Act . The other major leaders, Van Egmond, Samuel Lount, and Peter Matthews were arrested by the British; Van Egmond died in prison, and Lount and Matthews were executed at 8 AM on April 12, 1838, in Toronto . Their last words were: "Mr. Jarvis, do your duty; we are prepared to meet death and our Judge ." </P> <P> The rebels continued their raids into Canada, however, using the U.S. as a base of operations and cooperating with the U.S. Hunters' Lodges, dedicated to the overthrow of British rule in Canada . The raids did not end until the rebels and Hunters were decisively defeated at the Battle of the Windmill, nearly a year after the initial battle at Montgomery's Tavern . </P> <P> Compared to the Lower Canada Rebellion, the initial portion of the Upper Canada Rebellion was short and disorganized . However, the British government in London was very concerned about the rebellion, especially in light of the strong popular support for the rebels in the United States and the more serious crisis in Lower Canada . Bond Head was recalled in late 1837 and replaced with Sir George Arthur who arrived in Toronto in March 1838 . Parliament also sent Lord Durham to become Governor - in - Chief of the British North American colonies, so that Arthur reported to Durham . Durham was assigned to report on the grievances among the British North American colonists and find a way to appease them . His report eventually led to greater autonomy in the Canadian colonies, and the union of Upper and Lower Canada into the Province of Canada in 1840 . The populations of Upper and Lower Canada are listed on the Province of Canada wiki, and that of Canada West was not to exceed that of Canada East until 1850 . </P> <P> A number of the rebels were hanged including Samuel Lount and Peter Matthews, others were shot . Their deaths were a strong motivation for the continuing Patriot War . Many more prisoners were transported, but most were pardoned, e.g. Enoch Moore (Loyalist turned rebel). A general pardon (for everyone but Mackenzie) was issued in 1845, and Mackenzie himself was pardoned in 1849 and allowed to return to Canada, where he resumed his political career . Mackenzie was strongly disillusioned after his time in the United States, writing to his son that "after what I have seen here, I frankly confess to you that, had I passed nine years in the United States before, instead of after, the outbreak, I am sure I would have been the last man in America to be engaged in it ." In later life however, Mackenzie advocated annexation of Canada by the United States . </P>

Where did the most serious canadian revolt against british rule take place