German Student Union
The National Socialist party's state doctrine established anti-Semitism and the seizure of power. Hausdorff was not initially concerned by the "Law for the Restoration of the Professional Civil Service", adopted in 1933, because he had been a German official since before 1914. However, he was not completely spared, as one of his lectures was interrupted by Nazi students. He stopped his 1934/1935 winter semester Calculus III course from 20 November on. During that time, there was a working session of the National Socialist German Student Union (NSDStB) at the University of Bonn, which chose "Race and Ethnicity" as their theme for the semester. The assumption is that this event is related to the cancellation of Hausdorff's class, because otherwise he never, in his long career as a university teacher, stopped a class.