The 18th Ohio Infantry Regiment organized at Parkersburg, Virginia, and mustered in May 29, 1861, under Colonel Timothy Robbins Stanley in response to President Lincoln's call for 75,000 volunteers.
The regiment moved to Camp Dennison near Cincinnati, Ohio, and mustered in for three years service on November 4, 1861, under the command of Colonel Timothy R. Stanley.
Unattached, Railroad Guard, Army of the Ohio, to September 1862.
2nd Brigade, 2nd Division, Center, XIV Corps, Army of the Cumberland, to January 1863.
Organized at Chattanooga, Tenn., by consolidation of the Veteran detachments of the 1st, 2nd, 18th, 24th and 35th Ohio Infantry October 31, 1864.
This consolidated unit was attached to Post of Chattanooga, Dept.
of the Cumberland, to November, 1864 and continued to perform engineering duty.
In response to Hood's invasion, it was recalled to Nashville where it joined 2nd Brigade, 1st Separate Division, District of the Etowah, Dept.
[note 1] This brigade and the 1st Colored made the assaults on Hood's right at the Battle of Nashville.
Duty at Elizabethtown and Bacon Creek, Ky., November 1861 to February 1862.
Operations near Athens, Limestone Bridge, Mooresville and Elk River May 1–2.
Guard duty along Tennessee & Alabama Railroad from Tullahoma to McMinnville until September.
Passage of Cumberland Mountains and Tennessee River and Chickamauga Campaign August 16-September 22.