What did Lincolns call for volunteers to defend Fort Sumter lead directly to?
The question as to who started the war hinges on whether states which had voluntarily joined (and formed) the Union had a right to seceed from it, or not. The South said, “yes,” the North said “no.” If “yes,” holding and resupplying Ft. Sumter, in the territory of the Confederate state of South Carolina, was the cause. If “no” it was the Confederate attack. The War settled the issue.