General Sir Isaac Brock. Hamilton MacCarthy (1846-1939), Toronto, Ontario. Terracotta. 1896. General Sir Isaac Brock (1769-1812) was the commander of the British forces in Upper Canada at the beginning of the War of 1812. He was faced with the predicament that the majority of the population were post-Loyalist American settlers and therefore potential supporters of an American invasion. But Brock proved to be an astute and bold leader, and Upper Canada did not become part of the United States. Brock lost his life in the Battle of Queenston Heights on October 13, 1812.