Southern states were seceding before Lincoln ever set foot in the white house. The fist shots were fired by the south before he had a chance to issue an order.
The south went to war with a man who wasn’t even in office yet.
The entire purpose for Lincoln to engage the War of Northern Aggression was to “preserve the Union” (read Federal).
The Southern States were merely responding to the outrages that were being conducted by the Northern Industrial States.