After the Munich Conference, Adolf Hitler regretted having recalled his order to initiate hostilities. His “lesson” from Munich was never to pull back from war again, but to initiate hostilities in 1939. To keep his eastern border quiet while fighting Britain and France, he wanted the countries in the east to subordinate their policies to Germany. In the winter of 1938–39, he succeeded with Hungary and Lithuania. Poland’s leaders, though they considered substantial concessions in serious negotiations, were unwilling to surrender this country’s recently regained independence without a fight. Early in 1939 Hitler therefore decided to attack Poland in the fall and not to become involved in negotiations that might make it difficult to initiate hostilities, as he believed had happened in 1938. If Britain and France held to Poland, they would be fought at the same time; if not, their turn would come the following year. To avoid any danger of a peaceful settlement, his ambassadors in London, Paris, and Warsaw were kept from their posts in the critical days of August; and the final demands on Poland, designed to rally the German public, were withheld until they could be declared lapsed.

Rather than the initiatives of Japan in seizing Manchuria in 1931 or Italy in attacking Ethiopia (Abyssinia) in 1935, the war initiated by Germany on September 1, 1939 is taken as the beginning of World War II, because Japanese and Italian actions were continuations of prior expansionist policies, not the implementation of truly new policies. As Hitler had explained to his military commanders days before the invasion of Poland, this was a war for the annihilation of Poland and its people, not the attainment of some new border. His backdating his October 1939 authorization for the systematic killing of the handicapped and his moving forward the January 1939 public announcement of the intent to murder the Jews, in both cases to September 1, 1939, illuminate how Hitler saw the conflict as the beginning of the demographic revolution on a German-dominated globe. Neither the Italians nor the Japanese understood that this was not a war for specific pieces of land, bases, colonies, or status, like prior global conflicts such as the Seven Years War or World War I. This discrepancy in the purpose of the war contributed to the unwillingness and inability of the three nominal allies to develop substantial coordination in military operations and diplomacy.