Hermann Detzner is today merely a marginal figure in German colonial history. He was a personality who gained worldwide fame for a brief period in the 1920s. This fame was based on his alleged heroic deeds and research during World War I in the then-colony of German New Guinea. However, Detzner's military achievements and research findings were called into question. Ultimately, he had to publicly admit that his reports were largely products of his imagination, hearsay, assumptions, and speculations. Accordingly, his fall from colonial hero to a baron of lies was profound, and he became a dubious and controversial figure in German colonial history. The present study investigates what is true in Detzner's reports.