He was later convicted by the Central Criminal Court of collaboration for appearing in multiple propaganda films of the Nazi regime, but his sentence was overturned on the basis that he had worked under duress.

In June 1917, while under orders to return to France after sick leave, he absented himself; and in December was convicted at the Central Criminal Court on a charge of obtaining jewelry by fraud and sentenced to 6 months imprisonment at Wormwood Scrubs.

Sometime after the war, he married an Austrian woman named Alma, supposedly an illegitimate daughter of Crown Prince Rudolf, who committed suicide a year into their marriage.

He moved to Berlin in 1922 following an offer with producer Frederic Zelnik, and began acting in silent films under the stage name "Jack Trevor."

Over the course of the war, he appeared in several propaganda films, including Carl Peters, Ohm Krüger, and My Life for Ireland.