In 1946, the series delivered a powerful blow against the Ku Klux Klan's prospects in the northern US. The Anti Defamation League infiltrated the KKK and other racist/terrorist groups. Concerned that the organization had links to the government and police forces, the ADL decided to use their findings to strike at the Klan in a different way. They contacted the "Superman" producers and proposed a story where the superhero battles the Klan. Looking for new villains, the producers eagerly agreed. To that end, they provided information—including details of Klan rituals and the like to the writers. The result was a series of episodes, “Clan of the Fiery Cross”, in which Superman took on the Klan. The ADL tried to strip away the Klan's mystique. The trivialization of the Klan's rituals and natures had a negative impact on Klan recruiting and membership numbers.