The Battle of the Windmill was a battle fought in November 1838 in the aftermath of the Upper Canada Rebellion. Loyalist forces of the Upper Canadian government and American troops, aided by the Royal Navy and U.S. Navy, defeated an invasion attempt by a Hunter Patriot para-military unit based in the United States, which had the intention of using the beachhead as a launchpad for further offensives into Canada. Canadian, British, and American troops thwarted the invasion, successfully defending Canadian soil and forced the invaders to surrender. Others still in the U.S. were captured and arrested by U.S. officials.