He was 30 years old when he was enlisted (5 [33, probably when he reenlisted], 13 [48 at death in 1870]). He was born in Philadelphia, Pennsylvania (5).
He was 5 feet 7-1/2 inches tall, and had a fair complexion, blue eyes, and brown hair (5).
He was enlisted and mustered into service on 24 August 1861 (1, 5). He was enlisted for three years, at Philadelphia, Pennsylvania, by Colonel Reiff (5). He served in company C (1).
He fought at the Battle of Gettysburg (10).
He reenlisted as a veteran volunteer (1).
He was promoted from private to corporal on 1 April 1864, filling a vacancy (2).
He received a ten-day furlough on 20 September 1864 (6). He returned between 30 September and 6 October (7, 8).
On 5 November 1864, he was promoted from corporal to sergeant, effective 1 November 1864 (3, 4, 9).
He mustered out on 10 July 1865 with his company, as a sergeant (1).
On 17 July 1870, he died of general debility, in Philadelphia, Pennsylvania (12, 13). He was a shoemaker (13). He was married [?] (13). He died at, or was buried from 416 [??] Baltimore Street, Philadelphia, Pennsylvania (13). On 19 July 1870, he was buried, at Oddfellows Cemetery, Philadelphia, Pennsylvania (13).
On 3 September 1891, his widow, Mary McNally, applied successfully from Pennsylvania for a pension (11, 12).
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 31, HQ 91st PA, 1 April 1864 (William McNally)
3 special order 104, HQ 91st PA, 5 November 1864 (William McNally)
4 company C, List of non-commissioned officers, page 2, sergeants (Wm McNally)
5 company C, descriptive roll, entry 52 (William McNally)
6 consolidated morning report, 20 September 1864 (Corpl McNally)
7 consolidated morning report, 30 September 1864 (not named, but absent with leave)
8 consolidated morning report, 6 October 1864 (no enlisted men from company C absent with leave)
9 consolidated morning report, 91st Pennsylvania, 7 November 1864 (Corpl McNally)
10 Pennsylvania Memorial, Gettysburg, Pennsylvania (William McNally)
11 pension index, by name (William McNally)
12 pension index, by regiment, 91st PA Infantry, company C (William McNally)
13 death certificate, Philadelphia, Pennsylvania, 17 July 1870 (Wm McNally)
[I did not find an entry for him in Ancestry's index to the 1890 veteran's census (searched May 2007)]