Death at the local hospitals could come from almost anything.
I have one ancestor that died with smallpox at the Yankee Prison. No idea where he was buried.
I had one relative who was shot at Shiloh and was moved out with all the wounded and not a clue to when or where he died.
I had another connection who died of diarrhea in a Union hospital in Savannah, Georgia and who actually has a marked grave.
I have read that the filth and the conditions were quite hard on the men and of course there was no in door plumbing
or even anything to cut the germs. The local Wal-Mart Pharmacy would have been a God send to a hospital of that day.
I live within a few miles of where many men from Texas died of all sorts of disease, and were buried in central Arkansas.
They were scattered all over the countryside, sometimes being buried by the men who were dead in a few days themselves.
Poor man was doomed when he left home.