Thanks for saying that my ancestors were morons who had no idea what they were fighting for.
The fact that they had to go invade someone else ought to have been a clue, but Lincoln was locking up anyone who criticized or contradicted his claims, so people just generally shut up and obeyed.
Same thing with people they dragged off the boat and pressed into the army. It was made clear that they were expected to believe what they were told, and go fight and die in the South if necessary.