Hermann was German Freedom Front operative. In late 1947, after the death of Reinhard Heydrich, Hermann and GFF agents Max, Arnold and Konrad seized a TWA airliner on a flight from Amsterdam to New York City. They forced the plane to Madrid. They also demanded all prisoners in American custody be released. When the Americans did not act, they killed one of the passengers, David Levinsky, the only Jew aboard the plane. The group eventually set fire to the plane when their demands weren't met, and surrendered to Spanish custody. The U.S., Britain and France all demanded that they be turned over.