Fort Amherstburg was built at the mouth of the Detroit River to replace Fort Detroit , which Britain was required to cede to the United States of America in 1796 as a result of the Jay Treaty.

Built in the years before the War of 1812, Fort Amherstburg included "King's Navy Yard" for shipbuilding on the upper Great Lakes (lakes Erie, Huron, and Superior). The War of 1812 began when US General William Hull invaded Canada in 1812, and soldiers from the fort repelled the Americans at River Canard . After General Hull retreated back to Fort Detroit, British General Isaac Brock and the Shawnee Chief Tecumseh met at Fort Amherstburg to plan the attack of Fort Detroit. After losing the Battle of Lake Erie (including the flagship HMS Detroit, which was built at Fort Amherstburg), the British/Canadians destroyed the fort and retreated. The Americans built a new, smaller fort on the same site and called it Fort Malden . After the end of the war, the British/Canadians reclaimed (what is now) southern Ontario and Fort Malden.