After I posted I realized that what I meant to post was "Generally, secession was not thought to be unconstitutional until the concept was challenged by the Lincoln administration." My bad!
It was thought to be treasonous. "No man, no association of men, no state or set of states has a right to withdraw itself from this Union, of its own accord. "
One newspaper's opinion is still only one person's opinion, and we all know about opinions, ie - that everyone has one...... I believe that most folks held the opposite opinion.
“Secession is nothing but revolution. The framers of our constitution never exhausted so much labor, wisdom, and forbearance in its formation, and surrounded it with so many guards and securities, if it was intended to be broken by every member of the Confederacy at will. It was intended for "perpetual union" so expressed in the preamble, and for the establishment of a government, not a compact, which can only be dissolved by revolution, or the consent of all the people in convention assembled. It is idle to talk of secession. Anarchy would have been established, and not a government, by Washington, Hamilton, Jefferson, Madison, and the other patriots of the Revolution. – Robert E. Lee, January 21, 1861