From 1938 to 1945, Martin Niemöller was detained as 'Hitler's Personal Prisoner' in Nazi concentration camps. Liberated in April 1945, Niemöller was widely hailed as an icon of Christian resistance against the Nazi dictatorship. For many years, the Niemöller legend masked the problematic aspects of his life: his persistent antisemitism, on display even in the post-war period; his nationalism and support of the German war effort even whilst in concentration camp detention; and his disdain for parliamentary democracy. In his biography of the most important twentieth-century German Protestant, Benjamin Ziemann uncovers the 'historical' Niemöller behind the legend of the resistance hero. Carefully situating Niemöller's personal trajectory in his wider social milieu -- from the Imperial Navy to the West German peace movement -- Ziemann probes into core themes of twentieth century German history: militarism, National Socialism, German guilt, and moral reconstruction post-1945.