In 1915, the youngest man in the division, he was awarded the Iron Cross, 2nd class as the best scout in the region during the Battle of the Somme.

Following World War I Mauss joined the paramilitary groups Freikorps Oberland and Marinebrigade Ehrhardt and fought against the Silesian Uprisings.

Beginning in 1922, he studied dentistry at the University of Hamburg, attaining his doctorate in 1929 and opening a private dental practice.

At the start of the war, Mauss served with the 20th Motorized Infantry Division, with which he participated in the 1939 Invasion of Poland.

In May 1940 his 10th Panzer Division took part in the Battle of France together with Heinz Guderian's XIX Army Corps.