Mulholland was born in
Lisburn,
County Antrim,
Ireland (modern-day
Northern Ireland). Emigrating to
Philadelphia with his parents while a boy, his youthful tastes inclined him to military affairs and he became active in the ranks of the
militia. At the start of the Civil War he was commissioned
lieutenant colonel of the
116th Pennsylvania Infantry, which was attached to
Meagher's
Irish Brigade. When the regiment's size was reduced to a battalion, he accepted a reduction in rank to
major. He was wounded during the famous charge of the Irish Brigade up Marye's Heights at the
Battle of Fredericksburg on December 13, 1862. At the
Battle of Chancellorsville on May 3 and 4, 1863, he led his
regiment and distinguished himself by saving the guns of the
5th Maine Battery that had been abandoned to the enemy. For this he was complimented in general orders and later received the Medal of Honor from
Congress. In this campaign he was given the command of the picket line by
Maj. Gen. Winfield Scott Hancock and covered the retreat of the
Army of the Potomac across the
Rappahannock River. Although Mulholland later claimed that at the
Battle of Gettysburg on July 2, 1863, he personally took command of the
140th Pennsylvania Infantry and led it into action, this fact is mentioned in neither his own official report of the battle, nor that of the lieutenant colonel commanding the 140th. When the 116th was returned to full strength in early 1864, he was promoted to
colonel. He was wounded a second time at the
Battle of the Wilderness, May 5, 1864. At
Po River he was wounded a third time, but remained in hospital only ten days. Resuming his command, he was dangerously wounded again at the
Battle of Totopotomoy Creek. He recovered rapidly and commanded his brigade in all the actions around
Petersburg, particularly distinguishing himself by storming a fort on the Boydton Plank Road. Mulholland was mustered out of the volunteer service on June 3, 1865. After the war was over, he was elected as a companion the
Military Order of the Loyal Legion of the United States. On May 4, 1866,
President Andrew Johnson nominated Mulholland for the
brevet grade of
brigadier general of volunteers to rank from March 13, 1865, for his conduct at the Battle of the Wilderness and the
U.S. Senate confirmed the appointment on May 18, 1866. On January 13, 1869, President Johnson nominated Mulholland for appointment to the brevet grade of
major general of volunteers, to rank from March 13, 1865, for his actions on the Boydton Plank Road and the Senate confirmed the appointment on February 16, 1869. The brevet was issued February 20, 1869; it was the last brevet of major general issued for service during the Civil War. ==Postbellum==