Thanks so much, Steve! I also found after posting a citation in Red River Campaign: Politics and Cotton in the Civil War by Ludwell H. Johnson, Kent Ohio: Kent State University Press, 1993. Page 275. "Among the Northern dead [Battle of Yellow Bayou] was Colonel S. G. Hill's young son. 'I had often seen the boy at Alexandria,' said an enlisted man, 'and wondered why such a child should be in such a place. He rode a handsome pony and wore the infantry uniform, even to a little sword." He entered the fight at his father's side and was shot through the head."
Don't know why here the bay horse descriptor is omitted, but Johnson gives the same source (Van Alstyne's diary). Also, it notes a source for the second sentence as the O.R., XXXIV, Part i, 330.
My friend says that he remembers hearing that the boy's body was shipped back home in a cask of wine or claret to preserve it.
Marcy Frantom