The 125th Pennsylvania Volunteer Infantry Regiment lost 2 officers and 48 enlisted men killed or mortally wounded and 1 officer and 39 enlisted men to disease during the Civil War. It is honored by a monument at Antietam.

1862
August Recruited in Blair, Huntingdon and Cambria Counties and organized at Harrisburg for nine months service under the command of Colonel Jacob C. Higgins, former lieutenant colonel of the 1st Pennsylvania Cavalry.
August 16 Left State for Washington, D.C. and duty in its Defenses
September 6, March to Rockville, Md. and attached to 1st Brigade, 1st Division, 12th Army Corps, Army of the Potomac
September 16-17
Battle of Antietam

The regiment was commanded by Colonel Higgins. Adjutant Johnson was mortally wounded and four color bearers were shot down.

From the monument northwest of the Dunker Church at Antietam:

Color Sergeant George A. Simpson, Killed at Antietam

Moved at early dawn from bivouac on farm of George Line to East Woods near point where Gen. J.K.F. Mansfield was mortally wounded, from there to support Monroe’s First Rhode Island Battery on Smoketown Road, then to woods that stood here September 17, 1862, was the first Union Regiment therein. Being far advanced and without sufficient support, it was outflanked by the enemy and retired behind batteries in field in rear and subsequently saved the guns of Monroe’s Battery from capture. Remained in line until close of battle. Monument is near the left of its main line of battle.

Loss at Antietam
Killed and died of wounds 54  Seriously wounded 91 Slightly wounded and not reported 84
(total) 229

From the sign next to the monument:

While forming the extreme left front as Sedgwick’s Division was being shot down in the West Woods, the 125th Penna. Inf. Regt. was at times only 50 yards from Confederate Infantry. Of the regiment’s 54 killed and 91 wounded, most were lost here in the field in front of you. 9 to 9:20 a.m.

From the War Department marker to Crawford’s Brigade on the Antietam battlefield:

Crawford’s Brigade advanced from Line’s farm at daybreak, on the right of Williams’ Division. The 124th Pennsylvania was detached and supported Magilton’s Brigade of Meade’s Division in its engagement on the north edge of the Cornfield. In its deployment the Brigade moved to the left in support of Ricketts’ Division, a part of which it relieved at this point, and occupied the northeast corner of the Cornfield and a part of the East Woods, where it was heavily engaged. Upon the turning of the Confederate flank by Greene’s Division, the 125th Pennsylvania advanced across the fields north of the Smoketown Road and penetrated the woods around the Dunkard Church. The Brigade supported Sedgwick’s Division in its advance and, later in the day, formed in support of the Sixth Corps.

September 19-20 March to Pleasant Valley
October At Maryland Heights, attached to 2nd Brigade, 1st Division, 12th Army Corps
October 30 At Loudon Heights
November 8-19 Reconnaissance up the Shenandoah Valley
November Near Harper’s Ferry
December 10-15 March to Fredericksburg, then to Fairfax Station.
1863
January Attached to 2nd Brigade, 2nd Division, 12th Army Corps
January 20-24 Burnside’s 2nd Campaign, “Mud March”
February-April At Stafford Court House, Va.
April 27-May 6 Chancellorsville Campaign
May 1-5
Battle of Chancellorsville
May 18 Mustered out under the command of Colonel Higgins.