The biggest disappointment of Reconstruction was the rise of the Ku Klux Klan (KKK). The KKK was a secret society that used terrorism to intimidate and suppress African Americans. They hoped to prevent African Americans from exercising their newly gained rights, such as voting and owning land. The KKK also targeted white Republicans who supported Reconstruction. The KKK was very successful in its campaign of violence and terror, and it helped to undermine Reconstruction.