One of the biggest reasons the North went to war with the South was the fact that they would lose the warm water ports. We were just starting out of the Little Ice Age in 1861 and NY and Boston Harbors were mostly ice choked in winter. There go the tariffs and import/export business for the North. Lincoln had the businessmen screaming in one ear and the abolitionists in the other. The South seceded mostly to defend slavery, but the North went to war for that oldest of reasons....money.