One of the two major United States political parties, founded by a coalition in 1854. The coalition was composed of former members of the Whig, Free-Soil, and Know-Nothing parties, along with Northern Democrats who were dissatisfied with their party’s conciliatory attitude on the slavery issue. In 1860 their candidate, Abraham Lincoln, was elected to the presidency; the Southern states reacted by seceding from the Union, and the country was plunged into the Civil War (1861-1865).