It would have been impossible to do it at any point, and there should have been no fear of a war if Lincoln had chosen not to start one.
And of course, once again trot out your three little states that wrote about slavery being their primary cause, and ignore the other 8 that did not.
Virginia, the most notable and powerful of all the states at that time, clearly said they were seceding because Washington DC had become tyrannical and was abusing the power it had been given by calling for an invasion of the Southern states.
But you just keep forcing that history into the mold you are trying to create.
DiogenesLamp: "It would have been impossible to do it at any point..."
In 1860 virtually every American understood that slavery was a pre-condition for Union -- without slavery there would have been no Union and any blatant attempt at nationally imposed abolition would end the United States as it was then known.
So Republicans in 1860 merely wanted to return to the conditions of, say, 1788, when Congress could outlaw slavery in US Northwest Territories and states could abolish slavery within their own borders.
Nobody then proposed abolition in the South.
But that's not what Southern Fire Eaters said in 1861.
They said Republican efforts to restrict slavery were existential threats to slavery and reason-enough to justify secession.
Once civil war began, then all bets were off regarding abolition in Confederate states.
Contraband of War, confiscation of rebel property, enlistment of runaway slaves and emancipation in Confederate regions -- all became possible in a war of rebellion.
Also, with 11 slave-states seceded and their white voters self-disenfranchising, passage of the 13th Amendment made national abolition a political possibility.
And so it was done.
So, secession began to protect slavery, Civil War ended with it's constitutional abolition.
It was indeed, "all about slavery".
DiogenesLamp: "And of course, once again trot out your three little states that wrote about slavery being their primary cause, and ignore the other 8 that did not. "
Here again is that summary of seven (7) Reasons for Secession documents issued before Fort Sumter:
Summary: of seven (7) "Reasons for Secession" documents issued before Fort Sumter, all gave slavery as a major reason, three of them listed slavery as the only reason.