The 123rd New York Infantry was organized at Salem,[2] New York and mustered in for three years service on September 4, 1862 under the command of Colonel Archibald Livingston McDougall.
The regiment was attached to 2nd Brigade, 1st Division, XII Corps, Army of the Potomac, to May 1863.
1st Brigade, 1st Division, XX Corps, Army of the Cumberland, to June 1865.
The 123rd New York Infantry mustered out of service June 8, 1865.
Recruits and veterans were transferred to the 60th New York Volunteer Infantry.
Duty in the defenses of Washington, D.C., until September 29, 1862, and at Frederick, Md., and Sandy Hook until December 13, 1862.
Guard duty along Nashville & Chattanooga Railroad until April 1864.
Battles about Dallas, New Hope Church, and Allatoona Hills May 26-June 5.
Ruff's Station, Smyrna Camp Ground, July 4.
Thompson's Creek, near Chesterfield Court House, S.C., and near Cheraw March 2.