John Sappington Marmaduke (March 14, 1833December 28, 1887) was a regular army officer from the divided border-state of Missouri, who became a Confederate Major general during the American Civil War. Serving in Arkansas, he aroused controversy by killing his own commander in a duel, and was then accused of murdering African-American soldiers in the Red River Campaign. During Sterling Price’s raid into Missouri, Marmaduke was captured at the Battle of Mine Creek (October 1864) and remained in captivity until the war’s end. He became Governor of Missouri in 1884, successfully campaigning for railroad reform, before dying in office.