George Michael Decker Hahn, was an attorney, politician, publisher and planter in New Orleans, Louisiana. He served twice in Congress during two widely separated periods, elected first as a Unionist to the U.S. House of Representatives in 1862, as a Republican to the U.S. Senate in 1865, and later as a Republican to the U.S. House of Representatives in 1884. He was elected as the 19th Governor of Louisiana, serving from 1864 to 1865 during the American Civil War, when the state was occupied by Union troops.