Kampfbund für deutsche Kultur
In September 1932, Hirt joined the Militant League for German Culture. On 1 April 1933, he joined the Schutzstaffel (SS-Nr. 100 414), and was promoted to Hauptsturmführer (captain) on 1 July 1937, but he was only a member of the Nazi Party from 1 May 1937, when he enrolled in the universities of the Reich (Mitgliedsnr. 4012784). From 1 March 1942, he was a member of the personal staff of the RuSHA, the organisation in charge of "racial and ideological purity" of the members of the SS. He attained the rank of Sturmbannführer (major) in 1944.