The story that I have found was that Union Gen. Butterfield wrote this tune for his bugler to play at the burials of his men, rather than giving them a gun salute. The story goes that when his soldiers tried to bury their men after a battle in VA, they drew enemy fire from the Conferates when the Confederates heard the gun salute. Gen. Butterfield was determined that his men still would receive a proper ceremony, but also wanted to protect his living soldiers.