He was also a Nazi Party politician who participated in the Beer Hall Putsch and later served as the Gauleiter of Gau Magdeburg-Anhalt and as the Reichsstatthalter of the free states of Anhalt and Brunswick.

Born in Schwerin the son of a pharmacist, Loeper attended Volksschule at Rosslau and received his Abitur from the Friedrichs Gymnasium at Dessau in 1903.

He enlisted in the Imperial German Army as a Fahnenjunker (officer candidate) with Pioneer Battalion 3 in Spandau and then attended the War School at Neiße (today, Nysa, Poland).

For the next year he served with Infantry Regiment 150 in Allenstein (today, Olsztyn) and then was transferred to Pioneer Battalion 4 in Magdeburg, where he took command of a searchlight platoon in October 1913.

[2] After the war ended, Loeper remained in the military as the leader of a Freikorps unit that saw deployment both in the Baltic States and the Ruhr area.

Loeper was accepted into the Reichswehr, the armed forces of the Weimar Republic, in 1920 and became a company commander in Pioneer Battalion 2.

Loeper took part in the Beer Hall Putsch of 9 November 1923, and sought to enlist support for the coup from his commanding officer.

In 1932, he instituted the first Stammabteilung (main department) and the Führerschule (leadership school) of the Voluntary Labour Service at Dessau's Schloß Großkühnau [de].

[6] After the Nazis' nationwide seizure of power in January 1933, Loeper was appointed Reichsstatthalter (Reich Governor) for the Free States of Brunswick and Anhalt on 5 May.