In 1933 Schmitthoff was forced to leave Germany for England, to escape the anti-Semitic legislation introduced by the Nazi’s. In 1940, as a German citizen, he was interned in an ‘Aliens Internment Camp’ in York. The internship was not for long, and he spent much of the war in service in the Pioneer Corps and Canadian Engineers as a warrant officer. He was naturalised in 1946 and continued his successful career teaching law.