Establishment
The National Union Party was created in 1864 during the Civil War. A faction of anti-Lincoln Radical Republicans held the belief that Lincoln was incompetent, and therefore could not be re-elected. A number of Radical Republicans formed a party called the Radical Democracy Party, and a few hundred delegates convened in Cleveland starting on May 31, 1864, eventually nominating John C. Frémont, who had also been the Republicans' first presidential standard-bearer during the 1856 U.S. presidential election.
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