He was 39 years old when he was enrolled (5).
He was enrolled and mustered into service as a corporal on 27 June 1862, at Philadelphia, Pennsylvania (1, 3, 5). He served in company B (1).
He was discharged on 5 February 1863 on surgeon's certificate of disability (1 [Dec 62], 2, 3, 5 [Dec 62]). He was then a corporal (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)
2 consolidated morning report, 7 February 1863
3 list of non-commissioned officers, co.B (Robert McMullin)
4 company B [first] descriptive roll, entry 10 (Robert McMullin) [no information]
5 Civil War Veterans' Card File, available at the Pennsylvania State Archives, searched 30 May 2004 (Robert McMullin)
[I did not find an entry for him in the index on <www.ancestry.com> to the pension index by name (searched March 2007)]