I remember singing the Battle Hymn of the Republic somewhere. I don't remember which school it was.
I don't disagree with what you said. The problem with playing Dixie instead of the national anthem when the TV went off the air is it was done during the time of Jim Crow laws. A time when the south was being pressured to integrate the schools. Eisenhower had sent troops to Little Rock, Ark, a little before then. I walked past the black school and the white school before a reached my Catholic school.
My take is that the whole bit with reviving the Civil War, tearing down statues, banning flags and songs, etc is just part and parcel of the whole hate America agenda and the larger assault on Western Culture generally. It's happening everywhere - England, Ireland, France, Germany, Australia...basically anywhere that white people hold sway, which are incidentally the most successful societies. The real thing is they resent our outsized accomplishment and wish to blame us and tear us down to their level of disrepair under the banner of "equity".
The Confederates were as American as we are.