Almost every country in the world participated in World War II. Most were neutral at the beginning, but only relatively few nations remained neutral to the end. The Second World War pitted two alliances against each other, the Axis powers and the Allied powers; the Soviet Union serving 35 million, the U.S having served 16 million, Germany serving 13 million, and Japan serving 6 million men. With millions serving in other countries, an estimated 300 million soldiers saw combat. A total of 72 million people died with the lowest estimate being 40 million dead and the highest estimate being 120 million dead. The leading Axis powers were Nazi Germany, the Kingdom of Italy and the Empire of Japan; while the United Kingdom, the United States and the Soviet Union, were the "Big Three" Allied powers.