Slavery proved a very inflamed issue in the United States following their victory in the War of 1812, and even more so following their victory in the Mexican-American War, as those both in favor of and in opposition to slavery argued and fought over its existence. This did not sit well with the South. But, they and their supporters maintained some control, continuing to hold a majority in the Senate. Events over the next few years would calm down much of the Upper South - but at the same time inflame the so-called "Deep South."