The doctrine of "living space" and the pan-German ideal of uniting the German-speaking peoples would lead him to aggressive expansionism; In support of his belligerent policy, Hitler rearmed Germany and reorganized and modernized his army into a fearsome machine. France and Great Britain consented to the annexation of Austria and the occupation of Czechoslovakia, but the German invasion of Poland finally triggered World War II (1939-45), the first phase of which gave Hitler control of all of Europe except Great Britain. The failed invasion of Russia and the intervention of the United States reversed the course of the contest; Despite the inevitable defeat, Hitler rejected all negotiation,