He was 40 years old when he was enlisted (2).
He was enlisted and mustered into service on 17 September 1861 (1, 2 [2 Oct]). He was enlisted at Philadelphia, Pennsylvania (2). He was mustered in, at Philadelphia, Pennsylvania, as a private in company I (1, 2).
He deserted on 11 December 1861, from Philadelphia, Pennsylvani (1, 2).
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 Armstrong)
2 Civil War Veterans' Card File, available at the Pennsylvania State Archives, searched 28 March 2005 (Wm. Armstrong)
[I did not find an entry for him in the index on <www.ancestry.com> to the pension index by name (searched September 2006)]