Philip S. Lyman was born around May 1841 in Clermont County, Ohio, to Frederick Lyman and Hannah Chandler. His father was a miller and laborer who owned $100 of personal property in 1860. The family lived in Washington, Ohio, until the 1850s, when they moved to Delaware, Ohio. He married a woman named Emeline around 1861, and they had at least three children: William, born around 1861; John, born around 1864; and Walter, born around 1874.
Lyman enlisted in the Union army on April 21, 1861, and mustered in as a private in Company C of the 4th Ohio Infantry later that day. According to his service records, he had light hair and blue eyes. He mustered out on August 22, 1861, at the end of his three-month term of enlistment. He reenlisted four days later, and he mustered in as a private in Company A of the 18th United States Infantry. The regiment took part in the Battle of Shiloh, the Battle of Perryville, the Battle of Chickamauga, and the Atlanta campaign. He eventually earned a promotion to sergeant, and he mustered out on August 26, 1864.
Lyman settled in Chicago, Illinois, after the war, and he worked as a real estate agent. He applied for a federal pension in June 1880 and eventually secured one. By 1900, he was working as a carpenter. He died in Chicago on November 23, 1910.