The 151st Pennsylvania Infantry was a Union Army regiment serving for a term of nine months during the American Civil War.

[4] On February 10, the regiment received orders to march to the main winter quarters of the Army of the Potomac at Belle Plain, Virginia.

Late that afternoon, Confederate Lt. Gen Thomas ″Stonewall″ Jackson led his corps on a bold flanking maneuver and crushed the Federal right.

The 151st Pennsylvania was posted abutting the river and was tasked with guarding the main Federal supply and retreat route at United States Ford.

The I Corps remained mostly unengaged for the remainder of the battle, however the 151st Pennsylvania worked in conjunction with the nearby 12th Massachusetts to fight off a series of small incursions by Brig.

[9] As the regiment marched toward the area, they witnessed their corps commander Maj. Gen. Reynolds being carried to the rear on a stretcher, killed by a bullet to the head.

While placed near the Seminary, the 151st and other units began constructing crude breastworks in case the area should be needed as a defensive fall-back point.

At roughly 3:00 PM, the regiment - by now the last reserve of the I Corps - was ordered forward into a gap that had formed in the main Federal line on McPherson's Ridge.

Quickly forming their line on the ridge just in front of a woodlot named Herbst Woods, the regiment was immediately struck by a volley from Confederate troops in the trees.

McFarland recalled of the firing discipline, "This was strictly observed, and during the next hour's terrific fighting, many of the enemy were brought low.

"[11] The Iron Brigade, one of the first Federal infantry units engaged that morning, was positioned in McPherson's Woods not far to the north of the 151st Pennsylvania's right flank.

On the right of the 151st Pennsylvania, the other regiments of Rowley's brigade had held position for a period of time in the fields west of Gettysburg.

A short break in the fighting occurred as Lt. Gen. A. P. Hill rotated in a fresh division to carry on the attacks on the Federal lines near Gettysburg.

The Confederate division of Maj. Gen. William Dorsey Pender advanced toward Seminary Ridge and renewed the assault on the breaking Federal lines.

Unbeknownst to the men of the 151st Pennsylvania, Federal troops to the left had begun retreating through town to the high ground at Cemetery Hill.

[12] McFarland was treated inside the building, and once Confederate troops advanced and took possession of the town, fell captive to the enemy.

In the crowning charge of the third day of the battle, the shattered remnants of the One Hundred and Fifty-first Pennsylvania, with the Twentieth New York State Militia [alternate name of 80th New York], flung themselves upon the front of the rebel column, and drove it from the shelter of a slashing in which it had taken shelter from a flank attack of the Vermont troops.