I second that. I know from personal experience what this sort of research entails in time and ingenuity.

You've cleared up the mystery surrounding the song. More than that, you've established it as an important soldiers' song of the Civil War.

I have little doubt that the Cumberland Three's text has no basis in tradition. My copy of the CD issue credits Gil Kubin and the prolific Oscar Brand.

Many of the songs, in fact, are extensively (or entirely) rewritten.

The lines about the old man and his horse reappear in sea chanteys, notably "Poor Old Man (or "Horse").

Kudos again!