Further to your last post, I have found a litle more information. The 56th was organized at Camp Meigs, Readville, MA on 26 Dec 1863. The majority of volunteers to "C" Company professed prior service, although I have yet to confirm if this aplied to Michael. The Regiment engaged in the Battle of the Wilderness (6 May 1864), Spottsylvania (12 May 1864), and Spottsylvania Courthouse (18 May 1864) where McLean was ultimately wounded in the right forearm ending his military service. He was pensioned in June of 1865, and paid $18 per month. It would be interesting to find out how severe his injuries were and to what degree this might have affected his post-war life. Of course, the other important question to consider is what might have drawn McLean to Massachussetts in the first place: employment, the war, or, as a sailor, did he simply walk away from the ship he was crewing and join the war effort? I suppose we'll never know the answer to that one.
I would be happy to provide you with further info on my wife Theresa's connection to Michael, although it is a bit complicated. Feel free to contact me directly at Curtis_Mainville@hotmail.com