My guess the ultimatum in a nutshell was "we are leaving so leave us alone". If Lincoln really wanted his island fort in the middle of the Cooper River that bad, then 600,000 dead was the price of his stonewalling....
Why do you have to guess when the documentation is available for all to see online? The ultimatum was "we left so recognize us", period. Nothing for discussion. Lincoln's position was not open for negotiation. It was the rebel way or no way at all. So how can any rational person term that a 'negotiation'?
If Lincoln really wanted his island fort in the middle of the Cooper River that bad, then 600,000 dead was the price of his stonewalling....
You have that completely backwards, which is pretty much par for your course. It was Davis who felt Sumter was worth a war, and who led the country down the path of 600,000 dead in his losing effort. Was that worth it?