Werner Conze (1910–1986) is one of the most important, but also most controversial German historians of the 20th century. With his pioneering work in social and conceptual history, he contributed significantly to broadening the perspective of West German historical studies after 1945. As a young historian he had worked against National Socialism, which he never commented on publicly after the war. On the basis of a newly opened estate and other sources that have not been taken into account so far, the biography traces the historian's scientific and political metamorphoses between the Third Reich and the Federal Republic.