In 1918, he became a Professor at the . He succeeded August Endell as its Director in 1925 and served until its closure in 1932, following the emergency decrees issued by Heinrich Brüning. He then transferred to the Kunstakademie Düsseldorf, but was there for only a year when he was defamed and dismissed for being a purveyor of "degenerate art". A planned exhibition of his works was closed by the Nazi government in 1935. Two years later, thirty-five of his works were confiscated and displayed at the propagandistic Degenerate Art Exhibition in Munich.