Your rehash is the one most blatantly absurd. Lincoln was not protecting the Constitution.
Each state was a voluntary member of the nation. They were under no constitutional obligation to stay under the federal system.
Killing hundreds of thousands of citizens, impoverishing the people and shredding the Constitution did nothing to preserve this nation.
And yet when the New England states were mulling over secession during the days of the Essex Junto and the Hartford Convention, Southerners accused them of "treason" for wanting to dissolve the Union.