He served in the Royal Bavarian Army in the First World War and became a highly decorated general staff officer.

In July of that year, he entered the Royal Bavarian Army as a Fahnenjunker (military cadet) with Infantry Regiment 10 "King Ludwig" in Ingolstadt.

From October 1908 through September 1911, Hörauf attended the War Academy, which qualified him for a posting on the German General Staff at the age of only 33.

Hörauf was promoted to Hauptmann on 28 October 1912, and he returned to the War Academy on 1 April 1913 as an instructor of tactics until July 1914.

[1] At the beginning of the First World War, Hörauf became the general staff quartermaster officer at the III Army Corps in August 1914, with which he was deployed to the western front.

He was accepted into the Reichswehr of the new Weimar Republic, and served as the chief of staff of Brigade 21 (May 1919 to September 1920) and then of Infanterierführers VII in Munich (October 1920 to June 1921).

On 31 January 1928, Hörauf retired from active service with the rank of brevet Generalmajor, and he became a member of the conservative war veteran's organization, Der Stahlhelm.

[3] On 1 December 1930, Hörauf joined the Nazi Party (membership number 374,771) at the Ortsgruppe (local group) Bogenhausen.

Röhm chose Hörauf and several other old comrades from his Bavarian Army days for key assignments in staffing the SA leadership, in large part because he knew and trusted them.

At that point, he was released from active-duty SA status but remained on the staff of the OSAF as a leader available for special assignments.

Hörauf underwent a denazification process and, on 29 April 1948, he was initially classified in Group III (minor offender).