“You can’t know that. It is far more likely that threat would have been met by threat and war broken out before Lincoln was inaugurated rather than after.”
That is why I said likely, no one can know for certain.
What we do know was that President Buchanan and his administration worked with the secessionists and helped the secession.
Had there been a strong president from 1857 until 1861 who was dedicated to preserving the union and who threatened to use force against the secessionists, the Civil War might have been avoided. The lives of over 500,000 men would have been saved and the enormous cost and human suffering might have been prevented.
Agreed. I call Buchanan “The Feckless one”. However, it should be noted that in the waning days of his administration he did stand up to his cabinet - half of whom promptly resigned.
But the secessionists didn't come into play until Lincoln was elected. Strong or weak, the outgoing president couldn't prevent the election and he wouldn't have been able to prevent the Southern reaction to Lincoln's election. Negotiations would not have prevented Southern secession when they had no interest in negotiations, and threats of force would only have caused them to meet that threat with force of their own. The only thing the could have prevented Southern secession in 1860 was a Democrat victory.