June 18 – The U.S. declares war on Britain, beginning the War of 1812. There were about 4,000 British troops in Canada. George Prevost is Governor. Four Canadian battalions are assembled, and the Citadel at Quebec is guarded by the inhabitants.
July 11 – Americans under General William Hull invade Canada from Detroit.
August 16 – Isaac Brock with a force of 1,350, nearly half Aboriginals, takes Detroit. He paroles many of Hull's 2,000.
October – Almost half of Vermont's Legislators regard war as needless and impolitic; but Vermont imposes a penalty of $1,000 for every unauthorized communication with Canadians.
October 13 – Stephen Van Rensselaer IV's command is repulsed, on Queenston Heights by Gen. Sheaffe and Governor Brock, who is killed. Of the 10,000 under Van Rensselaer, many were unwilling to invade, though willing to defend the United States.