The War of 1812?

Leading up to and during the War of 1812, divisions between the Federalists and the Democratic-Republicans (political rifts), and eventually the Northern and Southern/Southwest states (regional rifts) became blatantly clear. The Federalists attempted to avoid all conflict, and were anti-war, whereas the Democratic-Republicans completely supported the war. Federalists also feared the acquisition of Canada; they worried that the new territory would provide the Democratic-Republicans with more power. Federalists made up most of the Northern states, whereas more of the Southern/Southwest states were major Jeffersonians, and the tension between the Northern and Southern states continued.