The 87th Pennsylvania Infantry was organized at York, Pennsylvania and mustered in for a three-year enlistment in September 1861 under the command of Colonel George Hay.
The regiment was attached to Railroad Guard, Middle Department, to May 1862.
Railroad Division, VIII Corps, Middle Department, to March 1863.
2nd Brigade, 2nd Division, VIII Corps, Middle Department, to June 1863.
1st Brigade, Elliott's Command, VIII Corps, to July 1863.
3rd Brigade, 3rd Division, III Corps, Army of the Potomac, to March 1864.
The 87th Pennsylvania Infantry mustered out of service at Alexandria, Virginia, on June 29, 1865.
Guard duty on Northern Central Railroad from Pennsylvania line to Baltimore, Md., September 16, 1861, to May 24, 1862.
Expedition under Gen. Kelly across Laurel Hill and Rich Mountain August 27-September 12.
Expedition over Cheat and Allegheny Mountains October 31-November 12.
Escort stores from Harper's Ferry to Washington, D.C., July 1–3.
Joined Army of the Potomac and pursuit of Lee July 5–24.
Wapping Heights, Manassas Gap, Va., July 23.