According to the compiled service record, he is listed on company H's muster-out roll, but not on any other roll of company H. Further, the index to the compiled service records has cards for only one John West (John L or John T, who served in companies D and H). I have therefore assumed that the references in Bates to John T West, John B West, and John J West are all to this person.
He was born in 1843/45. [sources: date: 2 (17 in 1861), 10 (16 in 1861)]
He enlisted and was mustered into service, at Philadelphia, Pennsylvania, on 25 September 1861 or 1 October 1861. He was mustered in as a private, in company H. [sources: 1 (25 Sep), 2 (1 Oct), 5-6 (mus, D and H), 7 (D, 1 Oct, mus), 8 (D, 3 Sep 61, pvt), 10 (D, 3 Sep 61, pvt), 11 (D, 1 Oct, pvt)]
He is listed on the company D muster-in roll, dated Philadephia, Pennsylvania, 7 October 1861. [source: 7]
He is listed on the company D muster roll for 11 September to 31 October 1861. He was reported discharged by the Court of Quarter Sessions, since he was a minor. The company D muster-out roll reports him discharged on 14 October 1862, but it seems more plausible that he was discharged in 1861. [sources: 7, 8, 9, 10]
He was discharged at Philadelphia, Pennsylvania, in November 1861, on writ of habeas corpus, because he was a minor. He was a private. [sources: 1, 2, 3, 4, 5-6 (D and H)]
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) (John T West)
2 Civil War Veterans' Card File, available at the Pennsylvania State Archives, searched 27 July 2004 (John T West)
3 company H, register of men discharged, #3 (John T West)
4 company H, descriptive roll, #24 (John T West)
5 index to compiled service records of volunteer Union soldiers who served in organizations from the state of Pennsylvania (John L West)
6 index to compiled service records of volunteer Union soldiers who served in organizations from the state of Pennsylvania (John T West)
7 compiled service record, D H 91st PA (John T West)
8 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) (John B West, co. D)
9 company D, register of men discharged, entry 13 (John T [?] West)
10 Civil War Veterans' Card File, available at the Pennsylvania State Archives, searched 30 July 2004 (John B West, co. D)
11 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) (John J West (D))
12 Civil War Veterans' Card File, available at the Pennsylvania State Archives, searched 30 July 2004 (John J West (D))