During 1918, he became a student of Arnold Sommerfeld and he received the doctor rerum naturalium from the University of Munich in 1920.
[1] From 1922 he did postgraduate work at the Stuttgart Technische Hochschule, under Paul Peter Ewald, also a former student of Arnold Sommerfeld, and he completed his Habilitation in 1924.
At Stuttgart he served as a Privatdozent and assistant to Ewald until 1929, during which time he worked on atomic and molecular structure and spectroscopy based on the Sommerfeld-Bohr theory.
[2][3][4] In 1933 Fues signed the Vow of allegiance of the Professors of the German Universities and High-Schools to Adolf Hitler and the National Socialistic State.
The institute followed the tradition of both Sommerfeld and Ewald in carrying on with both theoretical and experimental research and teaching.