I don't know if further delay would have changed the outcome--unless Lincoln called for troops secession of the Lower South would have remained the de facto reality, and if he allowed Fort Sumter to surrender because of lack of provisions the demoralizing affect of that on the North might have caused the attitude of "let the erring sisters depart in peace" to become even more widespread. Whenever Lincoln showed his hand that he would use force to coerce the seceded states back into the Union the Upper South would have been forced to decide whether to secede. Besides the four which did secede, two others (Kentucky and Missouri) struggled with the possibility.
“but “until after Fort Sumter” was just a shorthand way of referring to that”
I thought you might have been using such shorthand. I mentioned Lincoln’s call for 75,000 troops because others are likely not to know of it and that it provoked the Upper South to secede.
“unless Lincoln called for troops secession of the Lower South would have remained the de facto reality, and if he allowed Fort Sumter to surrender because of lack of provisions the demoralizing affect of that on the North might have caused the attitude of “let the erring sisters depart in peace” to become even more widespread.”
I fail to see what would have been wrong with that choice. The Constitution is silent on secession, and most Americans were aware that the United States were born in secession from the United Kingdom. It isn’t an issue that should have been entrusted to one man, especially in a country founded on a distrust of monarchical power.
Lincoln chose the route of war while Congress was out of session. He took it upon himself to decide the issue of secession and to declare war against several million American citizens- American citizens in his view of unfolding events, Confederate citizens in the view of the people he intended to force his will upon.
The seven state Confederacy would have been the old Texas Republic writ large- the Texas Republic that Abe Lincoln opposed admitting to the Union in the first place but which he now wanted to compel to remain- and the Texas Republic didn’t find its own independence satisfactory. The same would have happened to the small Confederacy over time. That Confederacy would have inconvenienced Mississippi River traffic but would have posed no other threat than perhaps an economic one of lower tariffs.
Had Lincoln not chosen war the issue of the Confederacy would have played out politically instead of in blood. The balance of power in Congress would have shifted dramatically to the North. The Fugitive Slave Act would have been repealed. A program of compensated emancipation like Britain employed could have ended slavery in the remaining US slave states, where slavery was more of an artifact from the past than in the cotton belt of the Deep South.
Only in Haiti and the US was the end of slavery accompanied by a bloodbath. In Haiti it was a slave uprising. In the US it was a political party deciding that secession as practiced by their fathers and grandfathers needed to be crushed by force.