He was born in 1832/33 (3 (28 in 1861), 5 (31 in 1861)). He was born in Ireland (5).
When he enlisted, he was 6 feet tall, and had a sandy complexion, light eyes, and sandy hair (5).
He enlisted and was mustered into service, at Philadelphia, Pennsylvania, on 30 September 1861 (1, 3). He was mustered in as a private, in company D (1, 3, 6).
He was transferred to company H on 31 October 1861 (2, 3 [from H to D], 4).
He was either not on the muster-out roll when the regiment mustered out (1 [co.D]), or was not accounted for (1 [co.H]). (The index to the compiled service records reports him a private in company D (6).)
According to the company H descriptive roll, he "deserted [and was] transferred by order of Col Reiff [?] USA" (5). Perhaps this means that he was transferred out of the 91st to another regiment, because he had deserted. Unfortunately, I have no other information about the transfer or the desertion.
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) (William Watson)
2 company D, register of men transferred, entry 21 (William Watson)
3 Civil War Veterans' Card File, available at the Pennsylvania State Archives, searched 10 August 2004 (William Watson)
4 company H, register of men transferred (William Watson)
5 company H, descriptive roll, #29 (William Watson)
6 index to compiled service records of volunteer Union soldiers who served in organizations from the state of Pennsylvania (William Watson)