James Duncan (September 29, 1811 – July 3, 1849) became a hero of the Mexican–American War for his capable command of an artillery battery at several important battles. He was a graduate of United States Military Academy in 1834 and served in the Seminole Wars. In 1848, he became involved in a post-war squabble between several general officers, though it did not harm his prospects. After his exploits in the Mexican–American War, he was appointed Inspector general of the US Army. A promising career was cut short when he died of yellow fever on an inspection tour of Mobile, Alabama in 1849.