How? I'm not Lincoln, I can't tell you exactly what he was thinking. All I can say is that I'm not aware of any thing he said or wrote that shows he knew without a shadow of a doubt that sending supplies to Sumter would result in war. If you do then how about producing it?
You know the answer. For some reason, you are just afraid to admit it.
He knew the consquences of resupplying Sumter, and he did it anyway...
I don't think it should be too much to ask for some honesty from you especially since you run roughshod over the Civil War threads demanding honesty from everyone else.