A reader tweeted a funny reply to my last article about American neglect of the First World War. He explained that modern viewers prefer the sequel to the original production: “Bigger explosions. Better villains.”

He’s right, of course. At the very end of a week’s tour of the battlefields, monuments, and cemeteries of the First World War, my son and I stopped at the memorial to the 1944-45 Battle of the Bulge, just outside Bastogne, Belgium. We arrived at sundown on a wet March afternoon. We saw more people at that one stop than we’d seen altogether at the American monuments at Belleau Wood and Chateau Thierry and at the Meuse-Argonne and Chateau Thierry cemeteries. I can be sure of the comparison, since the tally for the WW1 monuments was zero.

Bastogne, in fact, is a town only slightly less devoted to tourism than Niagara Falls, virtually all of it American. (The forlorn German cemetery near Bastogne, while well-tended, is poorly marked and evidently little visited.) At the handsome new war museum, I bought a Bastogne snow globe for my youngest daughter, featuring a little Sherman tank. The battlefields of the Argonne, on the other hand, upon which more Americans died in two months than died in all the Korean War, were tourist-free.

Americans are good at remembering what they want to remember. The hall where Patrick Henry spoke, the Old North Church in which Paul Revere saw the lantern, the hall in which the Declaration of Independence was signed, the houses of Washington, Jefferson, Madison, Hamilton, and Franklin—all survive or have been painstakingly reconstructed. Their counterparts from the French Revolution have almost entirely vanished. The educational effort at Civil War battlefields overwhelms anything at any European field I’ve ever seen. (Although the soon-to-open visitor center at Waterloo looks almost Gettysburg-like in scale.)

But Americans are also good at forgetting. Antebellum sites that survived or were reconstructed after the Civil War are typically purged of their slave quarters. A project to mark the sites of every lynching across the American South exists only in cyberspace. Demolition and removal are every bit as essential as construction and preservation to the creation of a usable past. Nobody would vacation in Colonial Williamsburg as it really was. Civil War re-enactors omit the amputations.

Yet forgetting has costs.

In 1917-18, Americans fought as something less than the overwhelmingly dominant partner in a coalition effort—something they would not do again for the next century and counting. The next era of world politics, however, seems likely to resemble the world of 1900 more than that of 1950 or 1990: a world of multiple, mutually suspicious great powers grouped in uneasy coalitions defined much more by interest than ideology. As the United States joins with India, Japan, Korea, and Vietnam to balance China, the First World War era may offer more positive and negative guidance for the future than the era when the United States was more lopsidedly supreme.

President Truman looks like a more successful coalition manager than President Wilson because of his superior skills—but also because he had an easier job. When you’re paying everybody’s bills, it’s easier to get your way. The presidents of the 21st century, however, will likely feel that their challenges resemble Wilson’s more than Truman’s or Eisenhower’s or Reagan’s. Their allies will be less ideologically and culturally comfortable than Churchill’s Britain or the democracies of NATO. Their economic and strategic superiority will be less overwhelming.

And perhaps in the 21st century, the proposition that the United States stands as an exception to the norms prevailing everywhere else in the developed world will also look more doubtful. “American exceptionalism,” as Americans began talking about it in the 1950s, rested on a series of claims about American history. It was claimed that because America had never known a feudal aristocracy, the United States had evolved as a uniquely classless society, at least for its white citizens. Because America was classless, the United States was uniquely immune to socialism and communism. This achievement came at a price however: a society uniquely indifferent to high culture, uniquely characterized by mass production and mass marketing.

These claims don’t seem very robust today. The United States is more, not less, class-bound than other developed countries. Socialism and communism are dead ideas everywhere in the developed world. Nor does American culture look so different from that of other rich countries as it did when Henry James lamented of the United States: “no literature, no novels, no museums, no pictures, no political society, no sporting class.” True, there's no other advanced country in which it’s as easy to start a new business, to reinvent one’s identity—or to massacre one’s neighbors. But this looks much more like a difference of degree than kind.

And maybe those claims weren’t ever quite so robust as they seemed in the aftermath of World War II. Look at the United States in 1919-22, and you see a country contending with convulsions very reminiscent of those that wracked the rest of the industrial world, from Moscow to Dublin. In just three years, 1919-22, the United States experienced the most violent race riots in its history; a wave of domestic terrorist attacks culminating in the deadliest bombing until Oklahoma City in 1995; and more and bigger strikes and labor unrest than ever before or since.

The image of the United States as a nation untouched by revolutionary ferment elsewhere doesn’t survive a study of that period. How unique even were the race riots? The white gangs that burned black businesses and expelled black families from their homes in Tulsa in 1921 bear a family resemblance to the paramilitary groups of demobilized German soldiers—Freikorps as they called themselves—who killed hundreds of Poles and Latvians in battles for control of Baltic and Silesian cities.

The United States did succeed better than most other countries in restoring order. Yet the means by which the United States did so also bore a family resemblance to other countries. Like Britain, the United States granted the vote to women—and like Britain, discovered that women voted more conservatively than men. The U.S. tightened immigration laws, also like Britain. Even alcohol prohibition was a global idea, imposed for the duration of the war in Britain and Canada—and only gradually relaxed in Canada over the course of the 1920s.

As Americans have become more uncertain of their nation’s continued hegemony, their leaders and would-be leaders have insisted ever more emphatically upon the doctrine of “American exceptionalism.” As a guide to action, however, the concept is proving of dwindling utility in the 21st century. The American state can still mobilize and deploy resources vastly greater than those of any other state. American policymakers, however, do not face a different geostrategic map from the policymakers of other and adversary countries, and American society does not belong to a different category than do the societies of other developed societies.

You might think that the last developed country to adopt universal health coverage would closely examine the systems developed elsewhere. You might think the designers of a new healthcare system for America would identify international best practices, while carefully assessing what might be applicable in American conditions and what would not. If so, you’d think wrong. The debate over healthcare reform unfurled with an almost surreal indifference to the rest of the world. Ditto for the debate over financial reform after the crisis of 2008. Ditto the debate over social mobility, over school performance, or over policing of disadvantaged communities.

In geostrategy too, the debate over America’s relative decline seems to pit those who would absolutely deny the reality of decline and those who welcome it. Yet the lesson of the decline of British power between 1870 and 1914 would seem to be that the post-American world will be a much more dangerous and violent place, as ambitious new contenders seek power in ever more aggressive ways. And the lesson of the 1914-1920 experience would seem to be that even a declining hegemony can still check its challengers, if it can find ways to convince new partners of the shared benefits of the old order.

On the night in 1864 on which he learned of his re-election, President Lincoln addressed well-wishers from the steps of the White House. The partisan crowd probably did not expect a lecture on the philosophy of history, but that’s what they got.

What has occurred in this case must ever recur in similar cases. Human nature will not change. In any future great national trial, compared with the men of this, we shall have as weak and as strong, as silly and as wise, as bad and as good. Let us, therefore, study the incidents of this, as philosophy to learn wisdom from, and none of them as wrongs to be revenged.

Lincoln was not preaching the ignorant doctrine that history repeats itself. (As the great medieval historian Roberto Lopez used to caution his students, history never repeats itself; it only appears to do so to those who don’t pay attention to details.) He was urging the importance of emancipating one’s mind from the narrow bounds of time and place. Good advice then. Good advice now.