There was certainly a Confederate nationalism which admitted centralized policies not popular in the South either before or after the Civil War for the sake of the war effort. But, the Confederacy was not a real country to Union soldiers, they faced a rebellion had to be put down to preserve the perpetual Union; that’s what some wrote their loved ones the night before they died in battle. See Gary Gallagher (2011) The Union War and James McPherson (1988, 2003) Battle Cry of Freedom. For some years after the conflict, the American Civil War was known as The Great Rebellion in the north.