If the first point were true, and that's all there was to it, then the Southern states would have accepted Lincoln's attempt to pass the FIRST 13th amendment to the constitution, which PROTECTED slavery. It passed both houses of congress, and was ready for the States to ratify it, Illinois actually doing so before the Confederacy was created. Lincoln had even signed it, as a gesture of resolve on his part. If slavery was THE cause, then that should have prevented the whole thing, but it didn't, the Southern states seceded anyway. Your second point is ridiculous. It was never postively decided that secession is outside the law, by the Supreme Court especially. Also, the Supreme Court's decisions following the war that dealt with Military Occupation and Rule in Southern States upheld those actions by resorting to International Law principles applying to independant nations. Easy to see what the implications of that were. They tried to deflect that in their summaries, but those were the only points of law they could use to justify it. Nearly all historians worth at least a thimble full of spit will admit the legality of secession was never settled by courts at that time, or since.
Not necessarily.
1) The Southern states probably didn't trust the Northern states to ratify the amendment. And were it ratified, the idea of unamendable amendments was constitutionally dubious. It's likely that the amendment protecting slavery could have been undone at some later date.
2) The lure of an independent slave/cotton nation on the Gulf was too strong. The belief, disputed by many at the time but also accepted by many in the Deep South, was that slavery would be stronger outside the Union than inside it. Rightly or wrongly, it was assumed that Southern slaveholding planters would look after the interests of Southern slaveholding planters and other Southerners far better than the government of a larger country.
3) The momentum was too strong to resist. It was either proclaim a new nation now, or back down. Fire-eaters had been working for an independent Southern nation for years. They would be discredited, if they backed down when their goal seemed within reach. When would another chance come to get their own country?
I wouldn't say that slavery motivated all rebels or secessionists. The Upper Southern states would not have seceded because of slavery alone. It was the coming of war that tipped them into the Confederate camp. And the reasons people gave for their own actions varied. But if we're looking for deeper, underlying causes, slavery accounts for far more than any alternative explanation.
This debate is a preoccupation of our time. Supporters of an independent slaveholding Confederacy talked about other topics (agrarianism, Southern nationalism, "state's rights", liberty and popular sovereignty), rather than slavery alone, but most weren't ashamed or emabarassed about their support for or acceptance of slavery, or racial subordination. It was after the war that supporters of secession came to be apologetic or embarassed or evasive about slavery.
Yes, President Lincoln was willing to largely placate the south in order to preserve the peace. Thanks for pointing that out.
What he --wouldn't do-- was agree to allow the expansion of slavery into the national territories.
And the war came -- because the slave power wouldn't agree to that.
They knew, and Lincoln knew, that if slavery were limited to the areas where it currently existed, it would die. Thomas Jefferson said that having slavery was like holding a wolf by the ears. You didn't like it, but you didn't dare let go. President Lincoln saw a way to let go and not have the wolf eat you. That is why he supported voting rights for blacks later on. Blacks were going to be in this country no matter what. The way had to be prepared.
That is why Booth shot him.
Walt