The trial of Captain Max Thierichens of the Imperial German Navy in Philadelphia in 1917 was a national sensation. His ship, the Prinz Eitel Fredrich, first sought refuge in the United States in 1915, but eventually the popularity of the captain and his crew became a liability as the country edged closer to war. In the hands of the infant Bureau of Investigation and the print media, Thierichens’s amorous adventures became federal crimes linked to an international campaign against sex trafficking. A propaganda windfall, these charges reflected the anti-German sentiments generated by the First World War, as well as other early twentieth-century social anxieties. In spite of his conviction and imprisonment, the actual facts of the case are still unclear. The personal and political purposes of the trial, however, are not. Ultimately, these highlight the vulnerability of American institutions to political pressure, popular prejudice, and social fears, especially in wartime.