A divided national party . . . voices of extreme rhetoric . . . an ugly, contentious primary season. Does this spell doom for two-party system?

Sounds modern, doesn’t it? But the year was 1860, and the party in question was founded by Thomas Jefferson, and shaped in the image of Andrew Jackson: The antebellum Democratic Party.

On the eve of Civil War, the future of the Union appeared in fatal doubt. Political leaders in the Deep South: South Carolina, Georgia, Alabama, Mississippi, and Florida had all but washed their hands of the centrally powerful United States. Adding to the precarious atmosphere, a faction of Democrats in the North promoted a policy to permit slavery into the western territories under the principle of Popular Sovereignty, or direct vote. Others voices in the northern branch of the Democratic Party believed the Southern States should depart the Union in peace. And these…