When the Soviet Union began building missile sites in Cuba in 1962.
Madison in his writings and speeches warned against the "tyranny of the majority" in democracy or the ability for the majority in a democracy to rule however it pleased because its powered was unchecked. Therefore, Madison did indeed believe that tyranny was possible in democracy because of this notion or fear of majority rule.
That means that slavery could’ve lasted longer if the south won the Civil War. If the Union hadn’t stayed together – that is, if the United States had broken into two – then it’s likely that other regions of the US would have taken advantage of Confederate secession or would have seceded themselves, either from the then-existing North or the South. So you could certainly see an independent Midwest, and the area from California through to Washington state probably could have made itself its own place. Even within the Confederacy, there were certainly sections like East Tennessee that were vigorously Unionist during the war, and which might have pulled away.
Hopefully this helped.