Seventy-four years ago this week, guns fell silent as the war in Europe finally came to an end. May 8th marks VE-Day, for Victory in Europe, when Nazi Germany surrendered to the Allies in 1945. Next month marks the seventy-fifth anniversary of the Normandy landings that marked the beginning of the end of Hitler. A critical question is what should we have learned from World War II, the last and most important time the U.S. and its allies prevailed in a global and very bloody conflict.First, allies count. In Europe, after France fell in 1940, Britain stood alone until June 22nd, 1941 when Hitler invaded Russia. Without the Red Army exacting huge casualties on the Wehrmacht and the RAF and RN keeping Hitler confined to the continent, German could have become the global language. In the Pacific, as the Japanese expanded its Greater East Asian Co-Prosperity Sphere westward throughout the Pacific, without Australia, India and New Zealand as part of the British empire and a few friendly bases in the Solomon Island chain, winning that war would have been far more difficult. Second, going to war against enemies with flawed strategic assumptions and aims helps. Having driven the allies out of the lowlands and France, Hitler believed he could win a two front war and defeat the Soviet Union. The Japanese high command misread America’s character and misjudged its reaction after losing much of its battleship fleet at Pearl Harbor on December 7th, 1941. The Japanese leadership assumed America would sue for peace and accept a truce that would enable Tokyo to keep its territorial gains. That did not happen. Third, mobilizing and creating a massive and responsive defense industrial base that would churn out tens of thousands of aircraft, warships, tanks and other sinews of war and raise a military force twelve million strong, along with nuclear weapons, was decisive.Fourth, a cogent and well conceived strategy matters. Churchill and Roosevelt were able to agree on and implement a strategy based on demanding an unconditional surrender by the enemy with focus first on the European theater and then engage the Soviet Union and other allies in this endeavor. Finally, public support was vital. Despite the isolationist years following World War I and great reluctance in becoming involved in the war in Europe that began in September 1939, American public support was instantly and dramatically reversed following the “dastardly” attack on Pearl Harbor.Obviously, many other factors in winning a world war were involved. However, the five conclusions noted above are sufficient metrics to use in evaluating the relevance of the current American strategy of conducting a global competition with peers and the requirement to deter and if war comes defeat a number of potential adversaries. Today, the U.S. has many allies, particularly NATO. But NATO’s coherence is being challenged by divisive domestic politics in several member states; uncertainty over the commitment of the Trump administration to the alliance; Russian meddling through “active measures;” and China’s “belt and road” and use of economic tools to exert influence and gain access to markets for goods, services and raw materials. Second, it is by no means clear that China or Russia suffer from the same flawed strategic thinking that doomed Nazi Germany and Japan.Third, while the U.S. defense industrial base produces marvelous weaponry, the time from conception to operation is measured in decades. Repair and replacement of these systems from battle damage in the event of war will also take time measured in many months or years.Fourth, no definition or concept of how to deter and defeat any of these potential adversaries mandated in the Pentagon strategy has been put forward in a cogent manner beyond basic aspirations and intentions. Last, it is unclear how much public support exists for American military interventions after almost two decades of engagements in Afghanistan as well as in Iraq, Libya, Syria and in the global war on terror.What this preliminary comparison suggests is that the U.S. must conduct a thorough analysis of the assumptions underwriting its national security and defense thinking. Of course, this is 2019 and not 1939 or 1941 or 1945. Of course, technologies and international politics change. Of course, thermonuclear weapons continue to threaten such destruction to suggest global war remains “unthinkable.”The end of World War II in Europe should remind of us what it takes to win a war as perhaps the best means of preventing a future conflict that could be massively destructive and conceivably existential. Or will we remain historically tone deaf as we have in the past?Dr. Harlan Ullman is UPI’s Arnaud deBorchgrave Distinguished Columnist. His latest book is Anatomy of Failure: Why America Has Lost Every War It Starts. The writer can be reached on Twitter @harlankullman.