The south left the union because they could get a better price for their goods from Europe than the north was willing to pay. The north instituted taxes that would force the south to sell to the north. The south did not like the deal and wanted out of the union. Read Lincoln's first inaugural address to see how he really felt about freeing the slaves.
If the north was so hell bent on freeing the slaves, why was the underground railroad underground in the north? When the allies liberating Europe from Hitler came across concentration camps, did they set the people free or did they treat the people like the north treated runaway slaves? Honestly if the north was fighting to free the slaves, why weren't they free as soon as they were north?
Slavery could of ended with out a war. It's days were all ready numbered. The war was fought to prevent the south from becoming free.
Look at the killing field called Gettysburg, and you can see the future killing fields in Cambodia.
You never read the Declarations of Secession have you?
Short answer to half of your misconceptions. There were thousands of abolitionist societies in the North. So my question to you is how many were there in the South?
By the way, don't waste anyone's time and telling me the South was getting rid of Slavery. Slavery ended at the point of a gun.