US Soldier killed on the Battle of the Little Big Horn. Original burial site. Sgt O'Hara enlisted into the US Army on October 30, 1872, at Columbus, OH. He was described as 58", gray eyes, light hair with a ruddy complexion. His civilian occupation was laborer. On December 9, 1872, O'Hara was assigned to Company M, 7th US Cavalry Regiment at Unionville, SC. On December 1, 1873, he was promoted to corporal. On August 2, 1875, O'Hara was promoted to sergeant. Company M was commanded by Captain Thomas French. At the Battle of the Little Bighorn, Company M was attached to Major Marcus Reno's Battalion. O'Hara was reportedly shot in the chest while on the skirmish line during the Valley Fight. He was the first known fatally wounded soldier of the battle. During the retreat from the Valley Fight, Pvt Edward Pigford reportedly assisted O'Hara to Reno Hill. The whereabouts of his remains were unknown until the 1990s. An archeological excavation of trooper entrenchments on Reno's Bluffs was conducted. The excavation uncovered the skeletal remains of a trooper. Research of 7th Cavalry enlistment records and reconstruction of the skull has led researchers to believe the remains found in the entrenchment belonged to Sgt. O'Hara. O'Hara was married and had one child. Names unknown.