Oliver S. Lyman was born around 1833 in Clermont County, Ohio, to Frederick and Hannah Lyman. His father was a miller who owned $100 of personal property by 1860. The family lived in Washington, Ohio, until the 1850s, when they moved to Delaware, Ohio. By 1860, Lyman was working as a laborer. He married Mary E. Morline on September 15, 1861, and they had no children.
He enlisted in the Union army on August 26, 1861, and he mustered in as a private in Company A of the 18th United States Infantry. According to his enlistment records, he was 5 feet, 8 ½ inches tall, with dark brown hair and blue eyes. The regiment took part in the Battle of Shiloh, the Battle of Perryville, the Battle of Chickamauga, and the Atlanta campaign. He remained devoted to the Union, writing that he was “fiting for are country that are fore fathers foght bled and died for.” He denounced northern Peace Democrats and insisted that they deserved death for undermining the Union war effort. As he explained in April 1863, “I wold like no better sport than to tye the knot round there necks and then give the order to draw it…I am hard harted enogh to cut there throtes and wold as leave shoot one as not.”
Confederate forces captured him near Pensacola, Florida, on May 31, 1864, and imprisoned him at Andersonville Prison. He died there of “Scorbutus” on October 27, 1864.