Here is something I wrote earlier about the Klan

The Klan started out as an organization that waged a campaign of violent terror against blacks and white Republicans in the South, especially in South Carolina. The federal government was actually pretty slow to react at first, with military units having orders to not interfere in affairs which were considered to be matters of the state/civilian governments. The Klan also outnumbered the federal forces in South Carolina, particularly in the Upstate. In some areas the Klan could gather a force of ~1000 men in only a few hours. After South Carolina Republicans lobbied the federal government enough, the Enforcement Act of 1871 aka the Ku Klux Klan Act was passed. The Act allowed for the suspension of habeas corpus and hundreds of members of the Klan were arrested or fined. However, some of the Klan leaders in South Carolina had gotten word of what was happening and fled the state; one even went to Canada. The Klan had also cut back on many of its activities prior to the arrival of federal troops with the enforcement act, so that past actions could not be prosecuted under the new act. While many members of the Klan were arrested, many were let go without punishment or simply fined. The judicial infrastructure could just not handle that many arrests or court cases. Very few Klan members went to trial and were found guilty. While some historians believe that the Enforcement Act completely destroyed the Klan, others disagree. One of those is Richard Zuczek in State of Rebellion: Reconstruction in South Carolina. Zuczek uses primary sources from those in charge of prosecuting the Klan in South Carolina to show that the Klan was not destroyed. He uses one contemporary quote that states the prosecutions "were largely a matter of sweeping dirt under the rug." So according to Zuczek, the Enforcement Acts may have curtailed Klan violence for a brief time but in the long run it actually emboldened Carolina whites hellbent on white supremacy. Many members of the Klan would also be apart of white leagues/rifle organizations/"social" clubs such as Ben Tillman and the Redshirts. These groups violently drove out the Republican government in 1876-1877

The Klan has always been a violent terrorist organization and it was first created to wage a guerrilla war against blacks and white Republicans during Reconstruction