John Holliday was a non-commissioned officer in Company C, 91st Ohio Volunteer Infantry Regiment; he joined the regiment in Spring 1864. During his service, he was promoted from corporal to sergeant, before mustering out.

The 91st Ohio was organized at Camp Ironton, Ohio, in August 1862 and mustered into service the next month. The regiment served briefly in the Ohio River Valley before transferring operations to West Virginia's Kanawha River Valley during winter 1862 and spring 1863. Apart from a brief foray into Ohio, the 91st spent most of the remainder of 1863 and early 1864 in West Virginia. After spring 1864, and until the close of the war, it operated in Virginia's New River and Shenandoah valleys, where it was mustered out in June 1865.

During Holliday's term of service, the regiment lost 63 men to battle and 90 to disease. Holliday survived, returning to his home in July 1865.