The 49th Pennsylvania Infantry was organized in Lewistown and Harrisburg, Pennsylvania and mustered in September 14, 1861 at Camp Curtin for a three-year enlistment under the command of Colonel William H. Irwin.
The regiment was attached to Hancock's Brigade, W. F. Smith's Division, Army of the Potomac, to March 1862.
1st Brigade, 2nd Division, IV Corps, Army of the Potomac, to May 1862.
1st Brigade, 2nd Division, VI Corps, Army of the Potomac, to February 1863.
3rd Brigade, 1st Division, VI Corps, to July 1864.
3rd Brigade, 1st Division, VI Corps, Army of the Shenandoah, to August 1864.
Reserve Division, Department of West Virginia, to September 1864.
Duty near Lewinsville, Va., defenses of Washington, D.C., until March 1862.
Pursuit to the Chickahominy River and picket duty until June 25.
White Oak Swamp Bridge June 30.
Assist in checking Pope's rout at Bull Run August 30, and cover retreat to Fairfax Court House August 31-September 1.
Jerusalem Plank Road, Weldon Railroad, June 22–23.
Repulse of Early's attack on Washington July 12–13.
Sheridan's Shenandoah Valley Campaign August to December.
Guard duty at Winchester until October 29, and in the valley until December 1.
Dabney's Mills, Hatcher's Run, February 5–7, 1865.