New Market Bridge, near Newport News

The regiment lost 1 officer and 6 enlisted men wounded.

Seven days before Richmond

Savage Station

Attacked by the 7th and 8th Georgia Infantry Regiments, then advanced two miles, followed by a charge on Confederate lines.

White Oak Swamp

The regiment lost 2 killed, 10 wounded and 20 captured or missing in a surprise attack on the camp.

Malvern Hill

Maryland Campaign

Crampton’s Pass, South Mountain

Battle of Antietam (Sharpsburg)

The 20th New York Infantry Regiment marched to the Antietam battlefield at dawn. It took part in a charge toward the Dunker Church, losing 9 officers and 42 men killed, 100 wounded and 2 men missing.

From the War Department markers (double marker number 74) on the Antietam battlefield:

Irwin’s Brigade came on the field about noon of the 17th, and formed across the Smoketown Road in rear of a line of Artillery.

After an unsuccessful attempt to penetrate the Confederate line south of the Dunkard Church, the Brigade rallied behind the ridge east of the Hagerstown Pike and between it and Mumma’s Lane, the left of the Brigade resting a few yards west of the lane, where it was exposed to a severe fire of Artillery and Sharpshooters.

About 5 P.M., the 7th Maine, on the left of the Brigade, crossed Mumma’s Lane, moved obliquely across the front of Brook’s Brigade, charged over the Bloody Lane at this point, dispersed the Confederates in its front and in the orchard on its left and reached the low ground North of Piper’s Barn, when the enemy from behind the stone fence on the Hagerstown Pike and the hill adjoining poured a severe fire on its right flank and front.

The regiment then obliqued to the left, passed through an opening in the fence into the orchard and to within 70 yards of Piper’s House, here it was met by a withering fire from a column of the enemy moving down the hill east of the house and driven back through the orchard with great loss.

It reformed a short distance east of this point and returned to the position from which it had advanced.

At noon of the 18th, the Brigade was relieved by Cochrane’s Brigade of Couch’s Division.

From the War Department marker (number 75) on the Antietam battlefield:

Irwin’s Brigade reached the field about noon of the 17th, formed line across the road at this point, and charged through the Batteries and across the fields in their front to check the advance of the Confederates from the West Woods. The direction of its advance was south of the Dunkard Church and, when its right Regiments, the 33d and 77th New York, were nearly abreast the Church, they received such a destructive fire on their right and rear as compelled them to retire to the cover of the ridge in front of the Church, the remainder of the Brigade forming on their left. Late in the day the 7th Maine charged across the Bloody Lane to Piper’s Barn and was repulsed with great loss.

About noon of the 18th the Brigade was relieved by Cochrane’s Brigade of Couch’s Division, and withdrawn to the rear.

From Colonel von Vegesack’s report:

“the regiment formed in line of battle in the woods on this side of Antietam Creek at about 11 o’clock a. m. on the 17th of September, 1862. Advancing through the woods the regiment came into an open field, where they attacked the enemy and drove him across the field and the adjoining heights. The regiment occupied these heights until relieved the next morning.”

Battle of Fredericksburg

Crossed the river and supported batteries to the east of the town.

Chancellorsville Campaign

Maryes Heights, Second Fredericksburg

Salem Heights

Banks’ Ford

The regiment was on the right flank of the advanced Union line of defense, on the high ground just north of the Plank Road. It was attacked by Early’s Brigade and held for an hour and a half of heavy fighting, when Colonel Ernst von Vegesack was wounded. When he fell the regiment broke and ran for the rear. It lost 9 enlisted men killed or mortally wounded, 6 officers and 83 enlisted men wounded and 4 officers and 106 enlisted men captured.