Actually, a lot of northerners liked the idea of owning slaves as well. It's that "northerner" really meant "urban dweller", and it was inconvenient to own slaves.
Furthermore, while many negros were slaves, there were in fact black slavemasters as well. See:
http://americancivilwar.com/authors/black_slaveowners.htm
for some details about that.
The American Civil War always was about taxation. Washington continued to increase taxes to cover increased armament and social programs that many southerners thought benefitted more urban (northern) populations more. They were probably right, so they formed the confederacy with the goal of seceding from the union, and keeping federal taxation minimal.
The emancipation proclaimation was a kind of a hail-mary play; Lincoln, a white supremecist, became sympathetic with the idea as a means to preserve unity. It worked, but the reprecussions are still felt today- other countries were able to abolish slavery by expiration, something that probably would've done a lot to resolve racial tensions in the US. Instead, using the abolishion as a weapon did nothing to empower blacks, and probably caused more to promote racial segregation than the slavery itself.