Do you already know his unit? I'm assuming he enlisted in a Confederate command from Arkansas. How do you know that he was taken to Nashville? Nashville was evacuated shortly Fort Donelson surrendered, so it's doubtful that hospital records survived from this confused period of time. Also, burials of Confederates on most cemeteries were done hastily and without permanent grave memorials. Even when we are sure where burials were made, many are still going to be marked "unknown".