William Lyon Mackenzie, a Reformer, was Toronto's first mayor, a position he only held for one year, losing to Tory Robert Baldwin Sullivan in 1835. Sullivan was replaced by Dr. Thomas David Morrison in 1836. Another Tory, George Gurnett, was elected in 1837. That year, Toronto was the site of the key events of the Upper Canada Rebellion. Mackenzie would eventually lead an assault on Montgomery's Tavern, beginning the Upper Canada Rebellion. The attacks were ineffectual, as British regulars, and the Canadian militia in Toronto went out to the rebel camp at Montgomery's Tavern and dispersed the rebels. Mackenzie and other Reformers escaped to the United States, while some rebel leaders, such as Samuel Lount and Peter Matthews, were hanged. Toronto would elect a succession of Tory or Conservative mayors, and it was not until the 1850s that a Reform member would be mayor again. Shortly after the rebellion, Toronto was ravaged by its first great fire in 1849. The fire was one of two great fires to occur in the city, with the other occurring in 1904.