I do believe the southern soldiers disliked the idea of a government far away telling them how to live and what to pay them among other things.
Somebody pointed out that many people hadn't ever been more than 100 miles from their homes. Part of it was that a war was a source of excitement, an excuse to travel, to partake of the pomp and glitz and glory of military service. Of course, it wasn't quite so much fun once they got there.