Amos, I can't prove that "I'm a Good Old Rebel" was intended satirically, but it seems likely.

The author, Major James Innes Randolph, Jr. (1837-1887), was a Confederate topographical engineer as well as a lawyer who had been educated in New York State. After the war, he became a newspaper editor and an occasional sculptor.

The song is printed in a semi-illiterate backwoods dialect, which tells me that Randolph is manufacturing a backwoods speaker utterly unlike himself. When nineteenth-century poets intended to be serious, they almost always wrote formally and with as much artistry as they could muster. What's more, the first critical mention of the song, in 1869, comments on its "happy vein of broad humor."

Randolph's song (the one usually sung) differs considerably from the much nastier and more xenophobic version collected by the Warners many decades later.

But the point is that it doesn't matter what Randolph intended. Nowadays, without some kind of explanation, the average audience will take his song as a straight glorification of killin' Yankees and hatin' the Freedmen's Bureau (not to mention the Constitution and the Declaration of Independence and the Yankee Eagle, etc., etc.).

As I've said on another thread, most people just don't seem to "get" irony.