Born in Ohio, John D. Brown was 21 years old and living in Garden Grove, Iowa, when he mustered in as fourth sergeant in Company L, 3d Iowa Cavalry. Brown was promoted to captain in March 1864. During Price's 1864 invasion of Missouri, Brown fought in Independence, at the Big Blue River (Byram's Ford), Mine Creek, Little Osage River, and at Charlot's Farm. Captain Brown was in command of 100 troopers from the 3d Iowa Cavalry assigned to guard Jefferson Davis after his capture in 1865. Brown mustered out of volunteer service on August 9, 1865, in Atlanta, Georgia, having served for the duration of the war in the 3d Iowa Cavalry. Brown went home to Garden Grove, returning to his pre-war occupation of farming and stock raising. In 1909 Brown was elected senator, serving two terms in the state legislature.
Howell, J. M., and Heman C. Smith, eds. History of Decatur County, Iowa and Its People, Vol. II. Chicago: S. J. Clarke Publishing Co., 1915.
Iowa Adjutant General. Roster and Record of Iowa Soldiers in the War of the Rebellion, Vol. IV. Des Moines, IA: Emory H. English, State Printer, 1910.