The greatest war in history began at dawn of September 1, 1939. On that day Germany invaded neighboring Poland, attacking without warning and with such shattering power and speed that the world gasped to see how easily the first step in Adolf Hitler's plan for the world conquest was being carried out. England and France declared war on Germany two days after the invasion, but is was already clear that the unprepared Allies would never be able to come to Poland's side in time. The Germans had introduced something new in the history of warfare - the blitzkrieg, or lightning war.