He was born in 1839/41 (6 (26 probably in 1863/64)). He was born in Ireland (6).
When he enlisted, he was 5 feet 10-1/2 inches tall, and had a fair complexion, blue eyes, and brown hair (6). He had an 'O' in blue on his left hand (6).
He enlisted and was mustered into service on 18 September 1861 (1, 6, 9). He was enlisted for three years, at Philadelphia, Pennsylvania, by Captain Smith (6). He was a private in company C (1, 12-13).
On 7 May 1863, he was reported missing in action (3 [see my note below], 10 [wounded in head], 11 [head]).
He reenlisted as a veteran volunteer (1).
He was wounded on 8 May 1864 at Laurel Hill, Virginia (1).
He was promoted to corporal on 23 September 1864, effective 1 September 1864 (2, 5).
On 21 February 1865, he went on a furlough, which ended on 8 March 1865 (4). He was declared absent without leave on 10 March 1865 (7). He returned on 11 March 1865 (4, 8).
He was reduced to the ranks (5).
He mustered out on 10 July 1865 with his company (1, 9). He was a private, in company C (12-13).
On 5 August 1871, he successfully applied for a pension (9).
1 Bates, Samuel Penniman. History of Pennsylvania volunteers, 1861-5. Harrisburg: B. Singerly, state printer, 1869-71. 5 volumes. 'Ninety-first regiment', volume 3, pages 186-233. (In the roster)
2 special order 82, HQ 91st PA, 23 September 1864
3 consolidated morning report, 91st PA, 7 May 1863
(Pri Oneill)
[This could be Thomas O'Neill]
4 enlisted men's furloughs (John ONeil)
5 company C, List of non-commissioned officers, page 2, corporals (John O'Neill)
6 company C, descriptive roll, entry 55 (John ONiel)
7 consolidated morning report, 91st Pennsylvania, 10 March 1865 (not named)
8 consolidated morning report, 91st Pennsylvania, 12 March 1865 (Corp Oneill)
9 pension index, by regiment, 91st PA Infantry, company C (John O'Neill)
10 'The ninety-first Pennsylvania volunteers', Philadelphia Press, Wednesday 13 May 1863, page 2 (John O'Neille)
11 'The Ninety-first Pennsylvania at Chancellorville', Philadelphia Inquirer 13 May 1863, page 8 (John O'Neille)
12 index to compiled service records of volunteer Union soldiers who served in organizations from the state of Pennsylvania (John O'Niel)
13 index to compiled service records of volunteer Union soldiers who served in organizations from the state of Pennsylvania (John O'Neil)