Nearly a lifetime of research and study by a veteran of World War II reveals the major political and military errors and mistakes which caused the greatest catastrophe in world history, almost lost the struggle with the greatest evil the world has ever known, failed to end the conflict in a decisive victory for the survival of freedom and democracy, subjected the world to almost half a century of fear and turmoil in the Cold War, and wasted vast world resources on armaments while hundreds of millions of people suffered from hunger, illness and death. This comprehensive analysis of the major issues and campaigns of World War II concentrates on what went wrong with the conduct of the war which needlessly prolonged its brutal end resulting in greatly increased suffering and death and shockingly reveals how desperately narrow was the margin between victory and defeat. The author convincingly concludes that only if nationalism yields to the enforcement of international law can the worldwide devastation of mass destruction be avoided. But the good news is that recent developments in international cooperation clearly indicates that the overwhelming majority of the nations of the world now recognize that world peace can only prevail under the enforcement of international law. Thus it is imperative that the United States must now exert the necessary leadership for the execution of a Treaty for ther Peaceful Settlement of International Disputes as the only effective means of maintaining world peace and avoiding a nuclear holocaust.