What were some reasons the Union went to War?

The most common response would be that the Civil War was fought over slavery. While abolitionists were seeking to resolve the slavery issue, their numbers were not high enough to catapult the country to war.

The reality is that it went much deeper than the issue of slavery. The Southern states felt that the federal government had too much control over what happened in their individual states. Slavery was part of it, but it was far from the only concern they had. They seceded from the Union in an effort to create their own sovereign nation where states' rights took precedence over the rights of the federal government.

On the other hand, the Northern states felt that the states did not have the right to secede from the Union. President Lincoln and many others felt that once a state joined the Union, it was a permanent commitment. The North went to war to prevent a division of the Union, not because of slavery. Abolition of slavery was a result of the war, but not necessarily the driving force that led the North and South to enter war.