At the age of sixteen, he was accepted as a student at the Kunstakademie Düsseldorf, where his instructors included Adolf Schill, Peter Janssen and Eduard von Gebhardt.

He then transferred to the Academy of Fine Arts, Munich, where he worked with the genre painter, Carl von Marr.

Despite serving as a non-commissioned officer in France and Belgium during World War I, he was able to continue exhibiting; notably at the Große Berliner Kunstausstellung.

Shortly after that, in 1937, Joseph Goebbels ordered the confiscation of all "degenerate art", which included Stern's works.

His honorable service in the war tended to mitigate the persecution somewhat, until late in 1938, when the Sturmabteilung invaded their home; destroying paintings and furniture.

They found refuge in a hospital, operated by the Sisters of Mercy, where his brother, Leopold, had worked as a doctor.