Slavery was not the cause of the war. Lincoln himself said as much. The Emancipation Proclamation was a tactic employed deep into the war by Lincoln to rally support for the war.
Tariffs that enriched Northern merchants at the expense of Southerners galvanized opposition to the Union much more than the right of rich plantation owners to hold slaves.
If the South had tried an insurgency style of warfare, wouldn't Lincoln's freeing of the slaves have created a counter insurgency in the South?
OK, so what was it that the south was importing in such massive quantities that the tariffs unfairly impacted them?