The 1860 Democratic Convention provided a textbook illustration of what happens when a party splits: disaster.
The Democratic Party had been the dominant political party for decades, but that solidarity began to crumble over the volatile issue of whether to introduce slavery into the western territories.
Southern Democrats sought to extend slavery into every new state admitted to the union, while many Northern Democrats were opposed.
Front-runner Senator Stephen A. Douglas of Illinois hoped to hold the party together by advocating a compromise position that would allow the residents of new states to determine the issue of slavery for themselves.
But delegates from seven deep Southern states refused to support him, and attempted to block Douglas’s nomination at the party convention.
When that failed, the pro-slavery delegates held their own convention, nominated their own candidate, Vice-President John C. Breckenridge of Kentucky, and endorsed a pro-slavery platform.
The split in the Democratic Party led to electoral disaster for both party factions, as it contributed to the rise of the anti-slavery Republican Party and its little-known candidate, Abraham Lincoln.
With only brief interruptions, the Republicans would hold the White House until 1912.