What makes no sense is the deflection and denial of the obvious, which is that the CSA was expressly committed to maintaining the evil system of slavery and that its leaders were willing to wage a civil war that was motivated by in part by a desire to remain free to own other human beings as property.
I don’t know that I would say the CSA was willing to wage a civil war. That implies aggression. The South decided it no longer wanted to remain in the Union, and it severed those ties politically and asked that the government of the United States honor them. It did not. An army was raised to bring these states back into the union, and for no other reason.
Let us look at Fort Sumter. South Carolina asked the federal government to vacate what they considered to now no longer be a federal fort, but property of the state. In the same way that the new United States asked the British to abandon its frontier forts along and west of the Appalachians. In fact, Fort Sumter was donated to the federal government to allow the US military to protect the harbor (the most important deep water harbor on the southern Atlantic coast, along with Savannah). The US troops were initially stationed at Fort Moultrie, which sits on Sullivan’s Island on the northern side of the harbor. Sumter is its own little island right smack in the harbor entrance. While SC negotiators went to Washington to work out conditions for assumption of federal property (aka pay for it, and their debts), the US troops moved to Fort Sumter, thereby threatening the harbor and the city. Meanwhile, Lincoln gave his inaugural address in which he expressly stated that he would not allow any state to leave the union. Implication being, he would not vacate Sumter. Lincoln then sent a ship to Fort Sumter to “resupply” the fort. South Carolina understandably took this as a hostile action, and fired on the fort and the resupply ship. Lincoln deliberately baited the South Carolina militia and the cadets at the Citadel into firing on the fort so he could have a casus belli for a war. In the same way that President Polk 12yrs earlier deliberately sent the US Army to camp in territory that Mexico believed and openly claimed was theirs in order to provoke Mexico into attacking US forces (which it saw as a hostile, invading force). The South no more started the Civil War than Mexico started the Mexican-American War. Had Lincoln instead desired peace, he would have had it. He did not.
One reason was trade concerns. Lincoln when advised to allow the southern states to leave peacefully:
“And open Charleston, etc as ports of entry, with their ten percent tariff. What, then, would become of my tariff?”
Senator Orville Browning to Lincoln:
In any conflict……between the government and seceding States, it is very important that the traitors shall be the aggressors, and that they be kept constantly and palpably in the wrong. The first attempt……to furnish supplies or reinforcements will induce aggression by South Carolina, and then the government will stand justified, before the entire country, in repelling that aggression, and retaking the forts.
Lincoln admitted as much himself (letter to Gustavus Fox, the naval officer who planned the resupply):
You and I both anticipated that the cause of the country would be advanced by making the attempt to provision Fort Sumter, even if it should fail, and it is no small consolation now to feel that our anticipation is justified by the result.
The South of 1861 was willing to wage war in the same way that 1938 Poland was willing to wage war.
You will note that the American Civil War is unique to civil wars as the “rebelling” states at no time sought to establish a new government of the United States; they sought only to maintain their status quo and felt that the federal system of government was no longer a beneficial compact for them. This of course revolved around slavery, but with that you had, for the previous 10yrs or so increasingly radicalized political parties. The John Brown saga was particularly disturbing to Southerners. Here you had an avowed terrorist who received financial backing from northern republicans to train a militia whose stated purpose was to murder southerners in their beds and instigate slave insurrection with the purpose of murdering more southerners. John Brown’s deputy actually went to two prominent senators, Senator Sewell (a republican frontrunner for president) and Senator Wilson (republican), and told them all the details of Brown’s planned attack on Harper’s Ferry. Senator Sewell expressed regret not that Brown planned to attack a federal arsonal, but that he had been told of the plan. Neither he nor Wilson reported this incident to the authorities. So here you have sitting Republican senators tacitly encouraging terrorism against their political opponents. And northerners, rather than condemning the violence, applauded it.
So leading up to 1861, the northern Republican party has actively pursued regional policies such as massive tariffs (47%) designed to benefit northern industry while harming the southern economy. This party has also increasingly supported radical terrorists like John Brown and even wrote a song about him as though he were a martyr when he was executed. And so, believing that the writing was on the wall, they elected to get out while the going was good.