He rose to the rank of SS-"Brigadeführer" in January 1939 and to SS-"Gruppenführer" in November 1940. On 1 April 1940, he was installed as "Reichsstatthalter" (Reich Governor) of Oberdonau. In July 1940, the "Donau-Zeitung" announced that August Eigruber would travel to Passau by ship. There, he would be ceremonially welcomed at City Hall, and attend the latest play by Hans Baumann. On 16 November 1942 came his appointment as Reich Defense Commissioner ("Reichsverteidigungskommissar") for his Gau. On 21 June 1943, Eigruber was promoted to the rank of SS-"Obergruppenführer". He was also made an SA-"Obergruppenführer" on 9 November 1943.