A lesson from D-Day: The world is better when we work together

"Lest we forget." Expect to hear those words often as we mark the 75th anniversary of D-Day this week. More than half a million Allied airmen, soldiers and sailors invaded France that cold and blustery morning. More than 4,000 would be dead by day's end. So, too, a thousand German soldiers and an estimated 3,000 French civilians. It was carnage.

Lives were lost every day of the war — in the Soviet Union, one life every four seconds — but D-Day holds a special place in American memory because it marked the beginning of the end of our nation's last clear-cut conflict between good and evil.

"Here the Allies stood and fought against tyranny in a giant undertaking unparalleled in human history," President Ronald Reagan once explained on the wind-swept cliff above the bloodiest beach of all. We'll hear similar invocations this week about bravery and sacrifice on behalf of this noblest of causes, and how we must aspire to such greatness today.

Those exhortations will be hollow if we fail to remember the real purpose behind those hallowed deaths, which was not merely the destruction of an evil regime but construction of a world capable of preventing its return. Today, nationalism, xenophobia, trade barriers and just plain hate — all the elements that produced World War II — once again dominate global politics. Even the war's simplest lesson, that Nazis are bad, finds critics — a development that would undoubtedly surprise and sadden the men of Omaha Beach and Point du Hoc. That is a shame. It is also dangerous, because "lest we forget" is not merely about remembering grand deeds of old. It is also a warning.

D-Day was nothing less than the down payment on an investment Americans had debated since their inception: Whether this country should build bridges to the rest of the world, or walls. The former brought costs but perhaps greater benefits. The latter meant isolation behind our splendid ocean moats, or at least engagement only when it suited our narrow needs alone.

This internal debate came to a head in the late 1930s. More than 100,000 American soldiers never returned from Europe's Great War a mere generation before and darkening war clouds across the Atlantic prompted opposition to any repetition. "We were fools to be sucked into a European war," Ernest Hemingway wrote, "and we should never be sucked in again." Germany's domination of Europe by late 1940 nonetheless forced the issue. Aiding Europe's imperiled democracies risked war. Doing nothing consigned the continent to its dark night, while leaving unchecked a threat that one day might transcend even our own security.

What historian Arthur Schlesinger later dubbed the "most bitter debate" of his lifetime pitted figures like "America first" exemplar Charles Lindbergh, who warned that opposition to Germany would "weaken the white races," against President Franklin Roosevelt, who dismissed his opponents as "softheaded isolationists." Privately Roosevelt thought "Lindbergh was a Nazi." Neither side budged.

War took a horrific toll on Europe and Asia. Death abounded, and by the war's end, millions of refugees haunted the continents' roads. Food and safety were scarce. Rape, cholera and rubble seemed the only things in great supply.

But in its wake came an unprecedented peace, one that has lasted for Europe, and more generally for the world, for over 75 years. More profound is the widespread amity and prosperity that have resulted. War and despair still exist, but on the whole, more people in more places were pulled from poverty and governed by peace than at any other time in human history.

This is no accident, but instead the legacy and the lesson of that charge up the beach in 1944. While numerous factors explain this postwar peace, including European integration, the rise of international cooperation embodied by the United Nations and fear of nuclear war, one factor has proved critical: American power and participation in the world. The United States' investment in preventing another world war through free trade and international engagement has been essential in forging what Roosevelt termed "a world unity that will spell a sure peace invulnerable to the schemings of unworthy men."

That commitment received its fullest endorsement on the beaches of Normandy that June day, when the United States' age-old internal debate died. Like Valley Forge and Gettysburg before it, the costly D-Day invasion taught a lesson: Liberty requires sacrifice. Understanding this, we've spent the ensuing decades devoting blood and treasure to engagement with the world. This effort hasn't always worked well, involving small but painful defeats in places like Vietnam and Iraq.

Yet even those lamentable losses proved far less costly than any large global war. Defense consumed more than 40% of the nation's total gross domestic product in 1944. It hasn't topped 10% since the mid-1960s. Today it is at 4%. More emphatically, 400,000 American service people fell during three-plus years of our full engagement in WWII. We've sacrificed fewer than 75,000 in the 75 years since. Each loss is tragic, yet more died in the first 48 hours after D-Day than in a decade of occupation in Iraq.

But Trump is wrong, and failure to appreciate this point denigrates the sacrifices of Normandy and of all the years since. The very costs Trump decries are what has kept the world at peace since WWII: reinforcing trade, security, commercial and cultural ties. Return on this investment has been massive — it saves us from needing to make the sacrifices required by total war like WWII, when we put over 10 percent of the nation in uniform and raised the highest marginal tax rate above 90%.

Those who made the ultimate sacrifice on the cliffs and beaches of Normandy died for more than their day's objective. They died for more than mere victory over a totalitarian threat. They and so many others of their generation, on battlefields far and wide and surely less famous, instead bought with their blood the peace we continue to enjoy today.

"This time we are not making the mistake of waiting until the end of the war to set up the machinery of peace," Roosevelt declared in his final address to Congress in 1945, one which promoted the United Nations. "This time, as we fight together to win the war finally, we work together to keep it from happening again," by supporting free trade and international cooperation and by paying the price of protecting the global commons.

Critics today foolishly decry this commitment because they have never known real carnage. They assume stability will endure, even as they hack away at its basic foundation. Perhaps they merely lack the imagination to fully comprehend the consequences. Perhaps there are simply not enough left who remember that June day in 1944 to hear firsthand that sacrifice is not just about valor, nor a life lost just a testament of bravery, but rather each is a cost, just like the cost of diplomacy and of international trade, borne by some so the rest may live on in peace.

"Lest we forget," the voices of those lost in wars past cry out, not so that they are remembered, but so we never add to their number again. Those who speak only of honor and duty on this anniversary of sacrifice therefore forget the lesson D-Day's witnesses would most like us to recall. Lest we forget, it will happen again.