Having agreed to the Constitution as a means of government, as well as a manner to settle disputes via Constitutional votes, it would have been far greater had the issues which led to secession, including the outcome of a Constitutional election, been settled according to the available Constitutional means, rather than standing on what was not said in the Constitution, and causing the deaths of 618,000 Americans to settle the question.
The South never challenged the legal election of Lincoln as President of the United States. There was no Constitutional basis to overturn that election and the Southern States did not want to rule the Northern States any more than Cuba wanted to rule Spain in 1897.
What the Southern States did was exercise a Constitutional right reserved to the States by the language of the Tenth Amendment:
"The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people."
The Tenth Amendment is the exact opposite of the Authoritarian Maxim -- WHATEVER IS NOT EXPLICITLY PERMITTED IS FORBIDDEN.
Unless the Constitution specifically mentioned that secession was specifically "prohibited by it to the States", the Tenth Amendment stated that such a powers was one of the "powers ..... reserved to the States".
If the Framers of the Bill of Rights intended otherwise, then they committed an enormous error of omission when they wrote the Tenth Amendment without ensuring that, somewhere else in the Constitution, the power of secession was "prohibited by it to the States".
Even marriages that start out by promising to last "till death do us part" have the future option of a legal divorce. The "Divorce Clause" of the Constitution was the Tenth Amendment.
Nobody needed to die just as neither spouse needs to die when the other spouse wants a legal divorce. Even after the bombardment of Fort Sumter, a military action that resulted in no deaths, dialog could have been maintained. Instead, the South was invaded by military force.
Much is written about every battle in the Civil War and it is undeniable that Lincoln was invaluable in winning that war.
However, it must also be examined if Lincoln blundered into a shooting war that might have been averted by more skillful diplomacy with the Southern States that had not yet seceded.
Interesting. Why would the president call for war over something explicitly not in the Constitution? Political negotiation would have been more prudent and perhaps averted conflict had Lincoln shown more diplomacy. Cooler heads prevail.