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When did Josef Mengele join the German military?
Josef Mengele was called up for service in the Wehrmacht in June 1940, some months after the outbreak of World War II
What was Josef Mengele's rank?
Josef Mengele served with the rank of SS-Untersturmführer in a medical reserve battalion until November 1940

Question: What did he do after 1940?
Self-contained rewrite: What did Josef Mengele do after 1940?