It is not clear Lincoln was fighting to destroy slavery. Maybe he was.
If he was, he was fighting to overthrow the U.S. constitution with violence - the constitution he twice took an oath to protect and defend as president.
This will be a surprise to many, but slavery was enshrined in the U.S. constitution from the beginning by an affirmative vote of New York, New Jersey, New Hampshire, Connecticut, Pennsylvania, Massachusetts, Delaware, Rhode Island and Maryland.
And, oh yes, Virginia, North and South Carolina, and Georgia.
It takes a peculiar sort of feller to so completely turn rhyme and reason on its head - but you are certainly are peculiar.
Only someone like you could purport that turning ones back on the constitution and breaking the pact that drew this nation together could ever possibly be a constitutional act. Or that a person who fought to defend the constitution from sedition and insurrection could ever possibly be considered attempting to “overthrow the U.S. constitution”.
Or that a constitution “enshrines” a peculiarity that it doesn’t even identify be name. Ridiculous? Of course. Perverse? You bet. Par for the course? Unfortunately yea.