Following the outbreak of war in 1939, Stauffenberg and his regiment took part in the attack on Poland. He supported the occupation of Poland and its handling by the Nazi regime and the use of Poles as slave workers to achieve German prosperity as well as German colonization and exploitation of Poland. The deeply rooted belief common in the German aristocracy was that the Eastern territories, populated predominantly by Poles and partly absorbed by Prussia in partitions of Poland, but taken from the German Empire after World War I, should be colonized as the Teutonic Knights had done in the Middle Ages. Stauffenberg said, "It is essential that we begin a systemic colonization in Poland. But I have no fear that this will not occur".