I just wanted to point out that althought there were slaves in the North. The slaves were orignally sold by their own people and brought to America. It is also true that the republicans were the ones that were against slavery.
Not really. Republicans may have had that as part of the platform, but too many Northerners were outraged at the thought of fighting a war over blacks/slavery for it to actually be important to all of them. I think abolitionists only made up ~10% of the (northern) population.