“It would be nice if cadets at West Point learned that anybody who’d take the oath and then lead armies against what was their country was dangerously irresponsible, though.”
Those that say “Lincoln and the North fought to free the slaves” need to read and comprehend what you have written.
Lee and others took an oath of loyalty to country and constitution and then led armies against what had been the US.
If Southern officers in the army and navy had made it clear from the beginning that they weren't going to take up arms against the United States, the country they'd sworn an oath of allegiance to, it would have taken the wind out of the movement for unilateral secession and the country's problems could have been resolved peacefully and amicably.
But they were too hungry for military glory. Or perhaps they were so used to not thinking about politics that at the one time when they needed to make a clear statement they couldn't do it.
As it was, plenty of Southerners in the navy and marines stayed in, notably David Farragut and Lee's cousin Samuel Phillips Lee. So did generals Winfield Scott and George Thomas.
You're the only one I know who says that.