Thaddeus Stevens (1792-1868) and Charles Sumner (1811-1874) were leaders of the Radical Republicans during Reconstruction (1865-1877). The Radical Republicans were a group of American politicians that belonged to the Republican Party and that fought with determination for a complete elimination of slavery and secessionism. Both Stevens and Sumner were zealous antislavery advocates, and they believed not only in freeing the slaves, but also in granting the same rights to the freedmen.