I have looked with no luck through my resources, but I will certainly keep John L(uther) Martin in mind.

I did find funeral home information for "Martin, 13 Dec 1862; Co. B 2 Mo.; V.B. Hospital, Grave 487."
V.B. = Vicksburg (but you knew that) and the grave number refers to area of Cedar Hill. (Too bad that reference map has been lost.)

Anna