[2] Returning to Austria, Reinthaller studied at the Agricultural College and became a forestry engineer in Lilienfeld, Attersee and Haus im Ennstal.

He rose through the ranks of Austria's Nazi set-up, becoming state peasant leader in 1934, although his moderate stance, particularly with regards to the use of violence, meant that he was often in conflict with Theodor Habicht who feared that Reinthaller was preparing to break away and form a specifically Austrian Nazi movement that would reject union with Germany.

[1] However Habicht did not move against Reinthaller, who enjoyed good personal relations with Rudolf Hess and Richard Walther Darré, albeit ultimately he was removed after he spearheaded his own negotiations with Engelbert Dollfuß.

Becoming a member of the Reichstag, he served as Minister for Agriculture in the cabinet of Arthur Seyss-Inquart from 12 March 1938 to 30 April 1939.

[1] Following this, he was appointed Undersecretary of State to the Reich Ministry of Food and Agriculture under his old friend Darré, and went on to fill a number of positions for the Nazi government, including Gauamtsleiter of the Lower Danube Landvolk, head of the Landesernährungsamt Donauland (regional Food Office) and an honorary Brigadeführer (Major General) in the SS.

[2][3] In April 1938, the Donau-Zeitung reported that Reinthaller took the Austrian Wotan steamer to Passau, where he welcomed German transport minister Julius Dorpmüller to Austria.

However, on 1 July 1949 the Counterintelligence Corps arrested Reinthaller at the request of Austrian police in Vienna, and extradited him to Austria to await trial.

Reinthaller was acquitted of high treason, but found guilty of being an active member of the Nazi Party before the Anchluss.