The new Justice Department prosecuted thousands of Ku Klux Klan members under the strict new laws .
Grant signed the Second Enforcement Act of 1871 into law , which made the Ku Klux Klan an illegal terrorist organization .
The new Justice Department prosecuted thousands of Ku Klux Klan members under the strict new laws , and Grant signed the Second Enforcement Act of 1871 into law , which made the KKK an illegal terrorist organization .