Complex sentence: The Knights of the White Camelia was an American political terrorist organization that operated in the southern United States in the 19th century, similar to and associated with the Ku Klux Klan, supporting white supremacy and opposing freedmen's rights.
Split into simpler sentences: The Knights of the White Camelia was an American political terrorist organization that operated in the Southern United States during the 19th century. Similar to and associated with the Ku Klux Klan, the Knights of the White Camelia supported white supremacy and opposed freedmen's rights.