http://www.pbs.org/wnet/jimcrow/stories_events_kkk.html
Ku Klux Klan, 1866
The Ku Klux Klan was originally organized in the winter of 1865-66 in Pulaski, Tennessee as a social club by six Confederate veterans. In the beginning, the Klan was a secret fraternity club rather than a terrorist organization. (Ku Klux was derived from the Greek "kuklos," meaning circle, and the English word clan.) The costume adopted by its members (disguises were quite common) was a mask and white robe and high conical pointed hat. 

According to the founders of the Klan, it had no malicious intent in the beginning. The Klan grew quickly and became a terrorist organization. It attracted former Civil War generals such as Nathan Bedford Forrest, the famed cavalry commander whose soldiers murdered captured black troops at Fort Pillow. 	
The Klan spread beyond Tennessee to every state in the South and included mayors, judges, and sheriffs as well as common criminals. The Klan systematically murdered black politicians and political leaders. It beat, whipped, and murdered thousands, and intimidated tens of thousands of others from voting. Blacks often tried to fight back, but they were outnumbered and out gunned. While the main targets of Klan wrath were the political and social leaders of the black community, blacks could be murdered for almost any reason. Men, women, children, aged and crippled, were victims. A 103-year-old woman was whipped, as was a completely paralyzed man. In Georgia, Abraham Colby, an organizer and leader in the black community, was whipped for hours in front of his wife and children. His little daughter begged the Klansman, "Don't take my daddy away." She never recovered from the sight and died soon after. In Mississippi, Jack Dupree's throat was cut and he was disemboweled in front of his wife, who had just given birth to twins. Klansman burned churches and schools, lynching teachers and educated blacks. Black landowners were driven off their property and murdered if they refused to leave. Blacks were whipped for refusing to work for whites, for having intimate relations with whites, for arguing with whites, for having jobs whites wanted, for reading a newspaper or having a book in their homes.. Or simply for being black. Klan violence led one black man to write: "We have very dark days here. The colored people are in despair. The rebels boast that the Negroes shall not have as much liberty now as they had under slavery. If things go on thus, our doom is sealed. God knows it is worse than slavery."
A few state governments fought back. In Tennessee and Arkansas, Republicans organized a police force that arrested Klansmen and carried out executions. In Texas, Governor Edmund Davis organized a crack state police unit, 40 percent of whose officers were black. The police made over 6,000 arrests and stopped the Klan. Armed groups of black and whites fought or threatened Klansman in North and South Carolina. The federal government also exerted its influence, empowering federal authorities with the Enforcement Acts of 1870 and 1871. Klan activity ended by 1872 and disappeared until it was revived again in 1915. 

-- Richard Wormser