Those five states didn’t go to war against the United States. The south could leave the union one of two ways - either negotiated with their partners or by waging war in which case all bets are off. They chose war.
And ruin.
They chose to leave. They chose to take back their own property. They didn't kill anyone.
The Union chose to invade, and it chose to kill people.
You have a funny way of characterizing who chose what.