He was 40 years old when he was enlisted (3).
He was enlisted and mustered into service on 18 September 1861 (1, 3). He was enlisted at Philadelphia, Pennsylvania (3). He was mustered in as a private, at Philadelphia, Pennsylvania (3). He served as a private in company D (1).
He was discharged at Washington DC, on 15 February 1862 or 16 February 1865 on surgeon's certificate of disability (1 [16 Feb 65], 2 [15 Feb 62], 3 [16 Feb 62]).
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 Roberts)
2 company D, register of men discharged, entry 1 (William Roberts)
3 Civil War Veterans' Card File, available at the Pennsylvania State Archives, searched 9 August 2004 (William Roberts)