There's no such thing as a "Union" at all if each state could simply walk out when the Federal government passed a law the state didn't like, or the country elected a President the state didn't like.

It's also of severe dubious moral quality when the whole reason you secede is merely because you see a threat to your system of institutionalized abuse, killing, slavery, and racial injustice.

You shouldn't get to simply join when the going is good for you, and stab the rest of the nation in the back only when the going is bad.

But with that said, you're right that Pres. Lincoln is not exactly the bright shining example of civil liberties that the other comments here have made him out to be. He did far worse things than Pres. Obama in his quest for national security...