Complex sentence: In September 1919, "The Crusader" announced the formation of a new organization called the African Blood Brotherhood (ABB), to serve as a self-defense organization for blacks threatened by race riots and lynchings.
Split into simpler sentences: In September 1919, "The Crusader" announced the formation of a new organization called the African Blood Brotherhood (ABB). Overtly it was said to serve as a self-defense organization for blacks threatened by race riots and lynchings.