Basically the Americans in the Revolutionary War in the south South believed that the Civil War was very necessary and it was just defense of their rights and liberties.
The revolutionaries and the Confederates had cast themselves as heroes resisting a tyrannical and authoritarian of the government that they felt no longer deserved obeisance.
The Union, like the British of the Revolutionary era, believed that they had to preserve their nation and prevent the new nation from breaking away.