 He established the "Deutsche Arbeiterpartei" (DAP; German Workers' Party) on 5 January 1919, together with the Thule Society's Karl Harrer.Adolf Hitler joined this party in September the same year.By the end of February 1920, the DAP had been reconstituted as the "Nationalsozialistische Deutsche Arbeiterpartei" (NSDAP; National Socialist German Workers' Party), often referred to as the Nazi Party.