James DeBow is not one of the better-known figures in American history. However, he was a major influence in pushing the South away from the North. He spread his views in part through his magazine "DeBow's Review."
DeBow believed strongly in the idea that the South needed to change its economy so that it could be more independent of the North. He felt that the South was, in essence, a colony of the North because it depended so much on the North for manufactured goods, shipping, etc.
In addition to this, he pushed hard to add more slave territory to the nation because he believed that the North would destroy slavery if it got majorities in Congress. He eventually came to advocate secession from the Union.
DeBow, then, is a relatively little-known figure who had a role in pushing the South to feel separate from, and ultimately secede from, the North.