Sergeant, Company G, 7th US Cavalry. During the Battle of the Little Big Horn, 25-27 June 1876, he was a Private in Company G, and survived the battle. He was later promoted to Sergeant.

The son of Francis and Mary Kelly O'Neill, he enlisted in Company M, 10th New York Infantry, during the Civil War. Liking the military, he served in the 1st Artillery, 1st Infantry, and 7th Cavalry, between 1865 and 1872. On 12 Dec 1872, he was sentenced by court-martial to confinement at hard labor and loss of $10 pay per month for 4 months for sleeping on guard duty. In June 1877, he re-enlisted into Company E, rising to the rank of First Sergeant. From 15 Nov 1883 to 14 Nov 1888, he was First Sergeant of Troop E, 7th Cavalry. He was retired, with disability (rheumatism and heart disease), on 27 Jan 1890, at Jefferson Barracks, MO. He moved to Washington DC, where he was a Sergeant of the Park Police. He died at 12:30 am of endocarditis and grippe.

Sergeant, Company G, 7th US Cavalry. During the Battle of the Little Big Horn, 25-27 June 1876, he was a Private in Company G, and survived the battle. He was later promoted to Sergeant.

The son of Francis and Mary Kelly O'Neill, he enlisted in Company M, 10th New York Infantry, during the Civil War. Liking the military, he served in the 1st Artillery, 1st Infantry, and 7th Cavalry, between 1865 and 1872. On 12 Dec 1872, he was sentenced by court-martial to confinement at hard labor and loss of $10 pay per month for 4 months for sleeping on guard duty. In June 1877, he re-enlisted into Company E, rising to the rank of First Sergeant. From 15 Nov 1883 to 14 Nov 1888, he was First Sergeant of Troop E, 7th Cavalry. He was retired, with disability (rheumatism and heart disease), on 27 Jan 1890, at Jefferson Barracks, MO. He moved to Washington DC, where he was a Sergeant of the Park Police. He died at 12:30 am of endocarditis and grippe.