A bombing raid in 1943 also destroyed Oppenheim's apartment in Berlin and with it much of his library and art collection. He then moved to Dresden, where he lived through the firebombing of February 1945. Having lost virtually all his possessions, Oppenheim moved to in Bavaria, where he stayed with his sister. He died on 15 November 1946 at the age of eighty six, in Landshut and is buried there.