So, do you doubt that Davis was fully warned, before Fort Sumter, that starting Civil War there would not end well for Confederates?
Why would he ignore such warnings?
The South did not start the War of Northern Aggression.
The cause was a host of economic and political aggressions by the North, and finally, the North’s refusal to peacefully accept secession.
Most notable among the North’s aggressions were their attempts to deny Southern states equal rights to lay claim to western territories.
The North and South were extremely polarized over the issue of slavery, but the polarization was often symbolic, as the polarization went way beyond slavery.
Both the North and the South saw expansion into Western territories as the key to future economic prosperity. Both sides knew that adding more states to their “side” gave them more resources, but also more power in the legislature.
As a result, there was fierce competition between the free states and the slave states to control these new states in order to gain political and economic control for their faction.
But what many forget, is that although they were called “free states” and “slave states”, the polarization between the factions went WAY beyond the issue of slavery.
Even apart from slavery, the Northern industrial states and the southern agricultural states had completely different economies, and completely different European trading partners. Federal laws, tariffs and other trade agreements that favored the North often punished the South, and visa versa.
Some of these laws and agreements involved slavery directly, but many did not.
When the Southern states attempted to exercise their constitutional rights to free trade, and their rights to westward expansion, they were stymied to the point of deciding to exercise their ultimate right - the right of secession.
It was the North’s refusal to allow the exercise these rights, including the right to secede, that started the War of Northern Aggression.