 In World War I, he was from 1916 to 1918 a member of the Deputy General Staff in Berlin.From 1919 to 1921 he declined three academic calls then accepted in 1922 a call to be Ordentlicher Professor at the University of Münster as successor to Leon Lichtenstein.From 1922 to 1926, he was assistant to Maximilian Krafft, with whom he wrote the textbook "Elliptischen Funktionen".