In this lecture, we will overview some of the attempts by the Allies to understand the mind of Hitler and the Nazis. Psychology and psychoanalysis were employed in the war effort against Germany in many shapes and forms, from the development of psychological profiles of Hitler to airborne leaflet drops. Air drop operations began over Kiel in September 1939 and continued until the surrender of Germany in May 1945, with the hope that the propaganda therein might cause people to discuss its content and demoralise the enemy. We will explore the fascinating1941 psychoanalytic interrogation of Rudolph Hess, who was diagnosed by British psychiatrists as being sane, but mentally unstable with hypochondria and a tendency towards paranoia. However, the use of psychology was not a one-sided affair - it was employed by the Third Reich and we will consider why the German people were held under the Reich's spell for so long. We will review how German psychiatrists advocated the practice of eugenics and how this became implicated in the Holocaust. Finally, we will introduce the recent evidence unearthed by Norman Ohler that, in the final year of war, there was widespread misuse of the methamphetamine-like substance Pervitin amongst German soldiers. Further, Hitler appears to have been addicted to the heroin-like substance Eukodol, which may have explained his increasingly erratic behaviour and erroneous military decision-making during the Battle of the Bulge. A lecture for those interested in the history of war, the history of science and the psychopathology of power and its loss.