Thomas J. Carter was born around 1840 in Ohio to Grayson Carter and Cassandra Smith. His father was a coal miner and shoemaker who owned $150 of real estate and $200 of personal property by 1860. The family moved to Jefferson, Pennsylvania, in the 1840s before settling in Millsboro, Pennsylvania, in the 1850s.
He enlisted in the Union army on September 4, 1862, and mustered in as a private in Company K of the 140th Pennsylvania Infantry later that day. The regiment took part in the Battle of Chancellorsville and the Battle of Gettysburg. Carter died at Gettysburg on July 2, 1863. As his brother George informed their parents, Thomas had returned from a hospital in Washington, D.C., only days before the battle began. George “dident want him to go in the battle but he said that the news never should go home that he died a coward.” George insisted that he had “died a good souger [soldier]” and “fell in a good Caus.”