When my grandparents went to World History class when they went to high school, they were taught that the Civil War started over unfair cotton trade first and slavery came second. This is true. The North was ripping the South off with cotton prices, so we went to war. Slavery was a sub-issue. As you can see, history has been twisted to make you believe the opposite.
Lincoln also wanted to send all the blacks back to Africa after they were freed, but found that it would be too cost-worthy.