The 123rd New York Infantry, enlisted in Washington County in August 1862 and mustered into U.S. service on September 4, joined the Army of the Potomac and fought at Chancellorsville and Gettysburg before transferring in September 1863 to the Army of the Cumberland, where it took part in the Atlanta campaign, the March to the Sea, and the campaign of the Carolinas, and it was mustered out at Washington at the close of the war on June 8, 1865. Its listed engagements included Chancellorsville, Kulp's Farm, Gettysburg, Chattahoochie River, Resaca, Peach Tree Creek, Cassville, Atlanta, New Hope Church, Montieth's Swamp, Lost Mt., Savannah, Pine Hill, Averysboro, Kennesaw, Bentonville, and Moccasin Swamp. At Gettysburg, on July 1 it marched from Littlestown, formed line of battle on Wolf Hill, and bivouacked near Baltimore Pike; on July 2 it advanced to this line and built a heavy breastwork of logs, then about 6 p.m. moved to support the left near Little Round Top, and when it returned in the night found its works occupied by the enemy because no troops had been left to hold them; on July 3 at about 11 a.m. it charged and recovered the works, about 4 p.m. moved to support the line and then repelled Pickett's Charge, later fought a sharp skirmish in front of the line, and at night repelled an attack with heavy loss to the enemy; on July 4 it made a reconnaissance around Wolf Hill and through Gettysburg over the Hanover Road.