Slavery wasn’t the real reason for the war. Lincoln did not want to lose the enormous taxes the south supplied to the federal government. He fell back on the issue of slavery as an excuse. Slavery in the north continued.
Funny, that wasn't what all those southerners were saying.
Shhh. Don't tell the Southern leaders of the time. They all thought they were acting to protect slavery and God knows what they'd do if you told them they were really rebelling over taxes.