They were part of the Union. They attacked that Union and undermined it. Traitors.
Wrong again. The South seceded. Went away peaceably. The North would not allow it.
Concerning Fort Sumter the North performed the first act of war when Anderson moved his troops from Fort Moultrie to Sumter which he was not supposed to do. Agreement had been made that there would be no change in the position of arms and troops until the negotiations of the forts was over.
Anderson moved his troops to the better defensive postion of Sumpter. That was an act of War. S. Carolina asked the President to send them back. He refused. Then later the Star of the West ship was sent to reinforce Sumter with men and arms and supplies. Another act of war.
In other words, the firing on Fort Sumter was not the act of war that started that war.
Quantrill