The challenge came from those dictators, first from Benito Mussolini, Duce of Italy, then from Adolf Hitler, Führer of a much more powerful Nazi Germany. The League of Nations proved disappointing to its supporters; it failed to resolve any of the threats posed by the dictators. British policy involved "appeasing" them in the hopes they would be satiated. By 1938 it was clear that war was looming, and that Germany had the world's most powerful military. The final act of appeasement came when Britain and France sacrificed Czechoslovakia to Hitler's demands at the Munich Agreement of September 1938. Instead of satiation, Hitler menaced Poland, and at last Prime Minister Neville Chamberlain dropped appeasement and stood firm in promising to defend Poland (31 March 1939). Hitler however cut a deal with Joseph Stalin to divide Eastern Europe (23 August 1939); when Germany did invade Poland in September 1939, Britain and France declared war, and the British Commonwealth followed London's lead.