 In February 1870, the Fifteenth Amendment was ratified; it was designed to protect blacks' right to vote from infringement by the states.White supremacist paramilitary organizations, allied with Southern Democrats, used intimidation, violence and even committed assassinations in order to repress blacks and prevent them from exercising their civil and political rights in elections from 1868 until the mid-1870s.The insurgent Ku Klux Klan (KKK) was formed in 1865 in Tennessee (as a backlash to defeat in the war) and it quickly became a powerful secret vigilante group, with chapters across the South.