John Carter Martin was born on August 21, 1837, in Manchester, Massachusetts, to George P. Martin and Sarah Carter. His father was a mariner who owned $300 of real estate in 1850. Martin attended school in Manchester before beginning work as a varnisher. He enlisted in the Union army on December 23, 1861, and mustered in as a private in Company H of the 29th Massachusetts Infantry later that day.
The regiment took part in the Peninsula campaign in 1862 as part of the Army of the Potomac. In January 1863, the army transferred the 29th Massachusetts to Kentucky, where it fought against Confederate guerrillas. The men helped besiege Vicksburg and Jackson, Mississippi, and took part in the Knoxville campaign. Then, in the spring of 1864, the army returned the regiment to the Army of the Potomac, and they joined the siege of Petersburg.
Martin was wounded in action at Shady Grove on June 2, 1864, and he was promoted to sergeant on December 1, 1864. On March 25, 1865, at the Battle of Fort Stedman, he was briefly "taken prisoner with a portion of his Reg[iment]," but he "escaped in the confusion...and rejoined the Regiment." He mustered out in Tennallytown, Maryland, on July 29, 1865.
Martin returned home to Manchester after the war and resumed his work as a varnisher. He married Amelia Juhnke there on February 21, 1867, and they had at least five children: Charles P, born around 1868; Ernest H., born around 1872; John H., born around 1875; Ella A., born around 1877; and Chester E., born around 1879. By 1870, Martin owned $600 in real estate. He died in Manchester on March 27, 1883.