The General Staff Division of Fremde Heere Ost (Military Intelligence Service, Eastern Section) which from 1942 was led by Reinhard Gehlen, was the nerve center of Hitler's military reconnaissance on the Eastern Front. This department worked professionally and was operationally and tactically reliable. However, at a strategic level there were clear deficits: the industrial capacity of the Soviet arms industry, the politico-military intentions and the details of the Red Army's plans for their offensive remained for the most part hidden from the department. When the Second World War ended, Gehlen put the documents and personnel of Fremde Heere Ost at the disposal of the Americans. With their support he was able to build a new foreign secret service which later evolved into the Federal Intelligence Service. In this book, military historian Magnus Pahl presents a complete overview of the structure, personnel and working methods of Fremde Heere Ost based on a tremendous array of archival sources. This work includes an extensive case study of the East Pomeranian Operation 1945. Pahl's study is a significant contribution to our understanding of German strategic, operational and tactical thinking on the Eastern Front 1941-45.