During the Civil War Henry served with Company "F", 171st Ohio Volunteer Infantry. On 9 August 1890 he was granted a pension as an invalid; on 22 August 1917 his second wife, Lottie, was granted a pension as an Army widow.
From the Geauga Leader, Burton, Geauga, Ohio, Tuesday, August 7, 1917: Henry T. Barnum of Hambden died July 28, of a illness of 4 years, having suffered a stroke. He was born in Braceville, Ohio, May 27, 1837, the youngest son of Samuel and Ficha Davis Barnum. He was married to Emily Cowles in 1858, and she died 15 years later. May 31, 1873, he married Lottie Davenport. He leaves 4 sons - from the first marriage W. H. Barnum surviving and from the second marriage Roy T., H. S. and Floyd Barnum surviving. Annetta and Isabelle died at an early age. The pallbearers were Elno Hubbard, Wesley and Clark Russell, Geo. Murray, Don Wedge and Cliff King. The funeral was Monday at 11 from his home and burial in Chardon cemetery.
Henry T. Barnum served in the Civil War, in Company E, 171st Ohio Infantry Regiment, from May 5 to August 20, 1864.