Final answer:
The Democratic Party split into two during the 1860 election, allowing the Republican party to win.
Step-by-step explanation:
The Democratic Party split into two during the presidential election of 1860, letting the minority party, the Republicans, win. The split occurred after the Democratic Party's convention in Charleston, South Carolina, and resulted in three factions: Stephen Douglas, John Breckinridge, and John Bell. This division presented an opportunity for the Republican candidate, Abraham Lincoln, to win the election.