I recently finished reading I'll Take My Stand: The South and the Agrarian Tradition, an interesting (if sometimes troubling) take from 1930 on the South and agrarianism vs industrialization in the south. It's a series of 12 essays about various topics impacting the south in the early part of the 20th century. As I was reading the post-script of my edition, it mentioned a collective of poets called "The Fugitives." Wikipedia has a good write-up on the individuals, but the gist is that it's a group of poets, chiefly centered around Tennessee, who were active in the 1920s.

I bring this up because several wrote about the Civil War and the South in general in similar sentiments to this poem. I've had a hard time finding any complete list of their works online, but it's certainly a place to start. I'm still not convinced the song is of antique origin, but I really have no proof for that.