Could the transcriber have misread 'Koshland' as 'Rockland' (as I did once!)? If so, Nicholas Rockland may not exist!
He was 20 years old when he was enlisted (2).
He was enlisted and mustered into service on 20 August 1861 (1, 2). He was enlisted at Philadelphia, Pennsylvania (2). He was mustered in as a private, at Philadelphia, Pennsylvania (2). He served as a private in company A (1).
He was not accounted for when the regiment mustered out (1).
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) (Nich's N Rockland)
2 Civil War Veterans' Card File, available at the Pennsylvania State Archives, searched 18 August 2004 (Nich's N Rockland)