The 9th Infantry Regiment ("Manchu") is a parent infantry regiment of the United States Army. Unrelated units designated the 9th Infantry Regiment were organized in the United States Army in 1798 during the Quasi-War, in 1812 during the war of 1812, and in 1847 during the Mexican–American War. The 1812 regiment fought in the Battle of Lundy's Lane, and the 1847 regiment in the Battle for Mexico City.