The German campaigns in Poland and the West in 1939 and 1940 ushered in a new era in warfare. The theory of the Blitzkrieg (Lightning War) developed by Hitler's forward-thinking generals - including the foreword writer, Heinz Guderian - was put into devastating effect. Based on a German book published during World War II and never before translated, Blitzkrieg in their own Words is a military history of these campaigns written by those taking part.