The regiment moved to Columbus, Ohio, on May 27 and mustered in on May 29, to date from April 27, 1861, under the command of Colonel Samuel Beatty.
Attached to Rosecran's Brigade, Army of West Virginia.
The 19th Ohio Infantry was reorganized at Alliance, Ohio and mustered in for three years service on September 25, 1861, under the command of Colonel Charles Frederick Manderson.
The regiment was attached to 11th Brigade, Army of the Ohio, to December 1861.
11th Brigade, 1st Division, Army of the Ohio, to March 1862.
11th Brigade, 5th Division, Army of the Ohio, to September 1862.
11th Brigade, 5th Division, II Corps, Army of the Ohio, to November 1862.
1st Brigade, 3rd Division, Left Wing, XIV Corps, Army of the Cumberland, to January 1863.
1st Brigade, 3rd Division, XXI Corps, Army of the Cumberland, to October 1863.
2nd Brigade, 3rd Division, IV Corps, to August 1865.
The 19th Ohio Infantry mustered out of service at San Antonio, Texas, on October 24, 1865.
Buell's Campaign in northern Alabama and middle Tennessee June to August.
Passage of the Cumberland Mountains and Tennessee River and Chickamauga Campaign August 16-September 22.
Atlanta Campaign May l-September 8, Duty at Parker's Gap May 6–18.
Operations on Pumpkin Vine Creek and battles about Dallas, New Hope Church and Allatoona Hills May 25-June 5.
Duty at Green Lake until September 11, and at San Antonio until October 21.