Born in Steyr, Austria, after finishing middle school, Eigruber underwent training in geodesy and fine mechanics at the Austrian Federal Teaching Institution for Iron- and Steelworking. Thereafter, he was active in his profession. In November 1922 he joined the NationalSocialist Worker Youth of Austria, whose leader he became in 1925. In April 1928, he joined the Nazi Party, whose Steyr-Land district leadership he took up in October 1930. For his activities in the NSDAP, which was banned in Austria, Eigruber was sentenced to several months in prison. From May 1935, Eigruber was the Gau Director for the banned Party in the Upper Austria Gau, and he took over complete leadership of the Gau as of 1936.
Rise to power in Nazi state
After the Anschluss, he was appointed Landeshauptmann of Upper Austria on 14 March 1938. On 10 April he was elected as a member of the German Reichstag, representing Austria. On 1 June 1938, Eigruber joined the SA, with the rank of SA-Brigadeführer effective 12 March. On 25 July, he also joined the SS as a Standartenführer also with an effective date of 12 March. On 22 May Adolf Hitler appointed him Gauleiter of Reichsgau Oberdonau. He thus united under his control the highest party and governmental offices in his jurisdiction. In September 1938, Gauleiter Eigruber attended the Reichsparteitag in Nuremberg. When PassauNational Socialists met at the Deutschmeister Inn, Eigruber joined his allies and reminisced about their venture during the Kampfjahre. 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 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 Defence Commissioner 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. Toward the end of the war, as US forces approached his capital at Linz, he proclaimed the city a "fortress" to be defended to the bitter end. However, shortly after the beginning of the offensive on 5 May 1945, he fled and proclaimed Linz an open city. He managed to hide out using forged identification papers until 11 August 1945, but was arrested by US Army Counterintelligence, in Sankt Pankraz.
