[1] With the help of a scholarship, Ehmsen was able to train as a decorative painter from 1906 to 1909 at the Kunstgewerbeschule Düsseldorf under Peter Behrens, Fritz Helmuth Ehmcke and Johannes Ludovicus Mathieu Lauweriks [de].
During a stay in Paris from 1910 to 1911, Ehmsen studied at the Académie Colarossi, and at the Le Dôme Café he had contacts with Ernesto de Fiori, Jules Pascin and Alfred Flechtheim.
On 24 March 1921, Ehmsen signed the guest book of Heinrich Kirchhoff [de] in Wiesbaden as a painter residing in Munich.
In the summer of 1921, Jawlensky rented Ehmsen's flat in Munich and from there visited Paul Klee, who was then living in Possenhofen on Lake Starnberg.
In 1930, he became a member of the Kampfkomitee der Künstler und Geistesarbeiter in support of the Communist Party of Germany in the Reichstag elections.
Because of a declaration of solidarity for the Paris Congrès mondial des partisans pour la paix (World Peace Movement), he was dismissed in 1949.