Are you thinking of Going Across The Mountain, which is about a man from the Southern Appalachians who joins the northern army in the American civil war? If so it used to be available on Topic 12T 162; Frank Proffitt, North Carolina Songs and Ballads, and is probably still available on CD through Folk Legacy.

The same song appears on Nothing Seems Better to Me; The Music of Frank Proffitt and North Carolina. The Warner Collection vol 2. Appleseed APR CD 1036.