The Allied victory in World War 2 was due to several key factors working together. The Allies gained control of the air and sea, allowing them to bomb German cities and industries while transporting troops and supplies. On the Eastern Front, the Soviets were able to mobilize their vast resources and grind down German forces. The entry of the U.S. into the war provided enormous human, economic, and military resources that exceeded Germany's capacity. Internally, the Nazi regime suffered from a lack of centralized control and efficiency that hampered its war effort.