Contrary to what you've been taught the Civil War was not fought to end slavery. In his inaugural address Lincoln made it clear that his objective was to preserve the Union,
His hidden agenda was to steal the sovereignty of the states and to create a nation with jurisdiction over the states. Before the war the government was the servant of the states and the people had inalienable rights, but after the war his mission was accomplished and the our rights became privileges and our responsibilities became immunities.
When Lincoln invaded the south, the southern states were paying over 80% of the taxes and the federal government could not survive without the taxes collected from the southern states. Lincoln looked at the southern states as a giant piggy bank and could allow them to leave the union.
We've been taught that the war was fought to end slavery, but this is simply not true. Like the patriots who took on the British, the southern states were fighting to defend themselves against a tyrannical oppressor.