One of the biggest problems of the war was slavery. the north did not supported slavery and the south did. there were many disputes but they still got over it with compromises. one the most famous compromises was the Missouri compromise.
The white abolitionist movement in the North was led by social reformers, especially William Lloyd Garrison, founder of the American Anti-Slavery Society; writers such as John Greenleaf Whittier and Harriet Beecher Stowe.