Thomas H. Capern was born around 1842 in New Jersey to Mary Capern. He enlisted in the Union army on August 23, 1861, and he mustered in as a private in Company E of the 4th New Jersey Infantry. The regiment took part in the Seven Days’ Battles, the Second Battle of Manassas, the Battle of Antietam, the Battle of Fredericksburg, the Battle of Chancellorsville, the Battle of Gettysburg, the Overland Campaign, the siege of Petersburg, and the Appomattox campaign. He expressed devotion to the Union, writing that “if a man were a true, genuine Christian, he would go in for the Union.” He supported Presidential Abraham Lincoln in the election of 1864. He mustered out on June 7, 1865.
He settled in Chester, New Jersey, after the war and earned a living as a farm laborer. He applied for a federal pension in October 1872 and eventually received one. He married Keziah Thomas on June 25, 1887, and they had no children. He died in Burlington County, New Jersey, on March 20, 1907.