The Radical Republicans were a political faction within the Republican Party originating from the party's founding in 1854—some six years before the Civil War—until the Compromise of 1877, which effectively ended Reconstruction. They called themselves "Radicals" because of their goal of immediate, complete, and permanent eradication of slavery in the United States. The Radical faction also included strong currents of nativism, anti-Catholicism, and support for the prohibition of alcoholic beverages. These policy goals and the rhetoric in their favor often made it extremely difficult for the Republican Party as a whole to avoid alienating large numbers of American voters of Irish Catholic, German, and other White ethnic backgrounds. In fact, even German-American Freethinkers and Forty-Eighters who, like Hermann Raster, otherwise sympathized with the Radical Republicans' aims, fought them tooth and nail over prohibition. They later became known as "Stalwarts".
The Radicals were opposed during the war by the Moderate Republicans (led by President Abraham Lincoln), and by the Democratic Party. Radicals led efforts after the war to establish civil rights for former slaves and fully implement emancipation. After unsuccessful measures in 1866 resulted in violence against former slaves in the former rebel states, Radicals pushed the Fourteenth Amendment for statutory protections through Congress. They opposed allowing ex-Confederate politicians and military veterans to retake political power in the Southern U.S., and emphasized equality, civil rights and voting rights for the "freedmen", i.e., former slaves who had been freed during or after the Civil War by the Emancipation Proclamation and the Thirteenth Amendment.