The Great Emancipation Proclamation didn't even cover slaves in Union states. The Confederacy desired to withdraw from an institution that no longer considered their needs as equal to the Union. Lincoln said it didn't matter what the Constitution said (i.e. "Reserved to the states") or didn't say (I.e. "Once joined, joined forever). The states were to bend to the will of an oppressive federal government or be damned. And damned we were; combatants and non-combatants alike.

“When Tyranny becomes Law, Rebellion becomes Duty”

Colossians 3:17 (New King James Version)
"And whatever you do in word or deed, do all in the name of the Lord Jesus, giving thanks to God the Father through Him."