"The Last Great Charge," I thought, was trad, a song from Atlantic Canada.
See http:///www.mun.ca/folklore/leach/songs/NFLD1/13A-07.htm

Guest, several songs, about Fredericksburg, etc., have a similar title (see Trad Ballad Index).
Please post the information from the copy you found in your Civil War lot- Publisher, composer, date, and other details- and I will try to check.