Everyone posting here believes in a "right of secession" -- lawful, Constitutional, peaceful secession -- as envisioned by our Founders.
They were all consistent in saying or implying that disunion must only come by "mutual consent" -- meaning Congress approves -- or through some "oppression" or "usurpation" making secession "necessary".
Our Founders also intended for the Supreme Court to settle disputes amongst states and Federal government, without secession.
What no Founder intended, and no state claimed, was a "right of secession" -- "at pleasure".
And yet, that's just what happened.
In early 1861, no seceding Deep-South state made use of available constitutional remedies for their grievances.
Instead they unilaterally declared secession, "at pleasure".
And what did the Federal Government under Presidents Buchanan and Lincoln do about it?
Basically, nothing, but speeches.
So Civil War came, in April 1861, not because the Deep-South declared secession, but because they started it, at Fort Sumter, and then formally declared war on the United States, on May 6, 1861.
Describing the circumstances as "at pleasure" is disingenuous considering the list of grievances listed in the SC Secession Declaration.
It would appear that South Carolina did use "available constitutional remedies". Buchanan may have been against secession but he believed states had the right, and the Court agreed and ruled as much in Dred and Kentucky v. Dennison.