This volume is one of a series produced by the American intelligence services after the Second World War, and written by captive German officers who had detailed knowledge of the operation. It looks at the political situation before the outbreak of war on 1 September 1939, as well as examining, in some detail, German military developments up to the start of the war The Polish military situation is included, together with the actual German plans for the invasion. Operations are reported in great detail, accompanied by maps. Operations by Army Groups North and South receive separate treatment, but are always linked at the strategic level. There is a chronological treatment of the first battles, and of the subsequent destruction of the Polish Armed Forces, as well as the intervention by Russian forces (under the terms of the Ribbentrop-Molotov agreement of August, 1939, which freed Hitler from the fear of a two-front war). There are ten maps of the developing military campaign. As the campaign which started the Second World War POland in 1939 deserves study, especially the German reactions to the lessons learned during the campaign, the solutions to which were in effect by May 1940 when the invasion of France and the Low Countries took place.