Actually, history may reveal that Lincoln declared war on the Confederacy to get them to become part of the Union. The evidence surrounding Fort Sumpter isn't in yet. Medical supplies were interpreted as weaponry and gave Lincoln a green light.

Still, Confederacy can't escape its association with the system of slavery. Lincoln didn't care about that in the beginning but he changed his mind in office.

The Confederacy wanted to declare themselves a country independent of the United States.
We should all be grateful that they never became one.