During the Nazi invasion of Poland, the Germans also carried out attacks on Polish controlled building in the Free City of Danzig, including the post office, which constituted extraterritorial Polish property. The Polish defense of the building, carried out by 55 lightly armed postmen against more than 200 German SS, SA and police troops, lasted for 15 hours. The Poles surrendered after the German forces used automatic pumps, gasoline tanks and flamethrowers to set the building on fire. Polish casualties were 6 killed during the fighting and 2 more killed while they were trying to surrender with a white flag. Four of the defenders managed to escape and six died in a Gestapo hospital. The rest were imprisoned, tortured, tried by a Wehrmachtcourt-martial and sentenced to death. 28 of the judgements were countersigned, and thus became legally valid, by General Hans Günther von Kluge, another 10 by Colonel Eduard Wagner A clemency appeal was rejected by Walther von Brauchitsch and carried out on September 8 and 30. Schenk began researching the events in 1993 and published a book, Die Post von Danzig: Geschichte eines deutschen Justizmords, which led to the revision of the verdict. He figured out that the German forces were Danzig police-, SS- and SA-men, commanded by a Danzig police officer, and only at a subsequent stage regular Wehrmacht forces did take part in the fighting. Thus a Wehrmacht court martial was not competent to convict the defenders. Instead, the Free City of Danzig's penal law would have been applicable, without the alternative of a death penalty. As a result, the judgements were nullified and the Polish defenders were "rehabilitated" by the Lübeck court. A symbolic reparation was made to the victims' families. On their initiative, Schenk was declared an honorary citizen of Gdańsk in 2003.
Dieter Schenk has also published books on the Nazi Gauleiter of Danzig-West Prussia, Albert Forster, Hitlers Mann in Danzig. In this book, Schenk documented that even after the end of the Intelligenzaktion in Pomerania, the Gestapo continued to carry out judicial murders. His other books include Krakauer Burg: Die Machtzentrale des Generalgouverneurs Hans Frank 1939-1945 about the Governor-General of Nazi-occupied portion of Poland called General Government, Hans Frank, Die braunen Wurzeln des BKA , which deals with the extensive influence that ex-Nazis held in post-war German Federal criminal police, Der Lemberger Professorenmord und der Holocaust in Ostgalizien and BKA - Polizeihilfe für Folterregime .