I'm linking several different Joseph Campbell entries in Bates. The index to the compiled military service records seems to confirm I have done this correctly.
He was born in 1823/24 (2 (37 in 1861), 6 [39], 8 [37], 9 (39 in 1863)). He was born in Donegal, Ireland (2, 8, 9).
He was a gardener or a laborer when he was enlisted (2 [laborer], 6 [gardener], 8 [gardener], 9 [gardener]). He was living in Philadelphia, Pennsylvania, when he was enrolled (6).
When he enlisted, he was 5 feet 9 inches tall, had a dark complexion, blue eyes, and dark hair (2, 6 [5'8-3/4", light complexion, gray eyes, dark hair], 8 [5'8-3/4", light complexion, grey eyes, dark hair], 9 [5'9", light complexion, grey eyes, dark hair]).
He enlisted and was mustered into service on 6 September 1861, at Philadelphia, Pennsylvania, for three years (1 [also has 23 November], 2, 6, 8). He was enlisted by Captain Lentz, and mustered into service by Captain Starr (2, 8 [enlisted by Starr]). He was a private, in company E (1, 10).
He was transferred on 31 December 1861 to company G, because company E was over the maximum number (1, 2, 3, 6).
He reenlisted as a veteran volunteer on 26 December 1863 (1, 6, 9). He was enlisted for three years, at Bealton, Virginia, by Lieutenant Swan (9).
On 5 November 1864, he was promoted to corporal, effective 1 November 1864, by special offer 104 (4, 6, 7, 8).
On 8 March 1865, he went on a furlough, which expired on 23 March 1865 (5). He returned on 24 March 1865 (5).
He mustered out on 10 July 1865 with his company (1, 6). He was a corporal in company G (1, 10 (pvt)).
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 descriptive roll, company E, entry 29
3 register of men transferred, company E, entry 3
4 special order 104, HQ 91st PA, 5 November 1864 (Jos Campbell)
5 enlisted men's furloughs (Jos. Campbell)
6 Civil War Veterans' Card File, available at the Pennsylvania State Archives, searched 5 May 2004 (Joseph Campbell)
7 company G, list of non-commissioned officers (Joseph Campbell)
8 company G, descriptive roll, entry 29 (Joseph Cambell)
9 company G, second descriptive roll, entry [13] (Joseph W Campbell)
10 index to compiled service records of volunteer Union soldiers who served in organizations from the state of Pennsylvania (Joseph Campbell)