Can Europe’s order survive as memory of war fades?

The Rev. Joseph Musser’s family has always lived in the region of Alsace, but not always in the same country.

His grandfather fought for the Germans in World War I, and his father for the French in World War II. Today, no one is fighting anymore. His great-niece lives in France but works in Germany, crossing the border her ancestors died fighting over.

It is this era of peace and borderless prosperity that champions of the European Union consider the bloc’s singular achievement.

“The foundation of the European Union is the memory of war,” said Musser, 72. “But that memory is fading.”

Today, as world leaders gather in Paris to mark the centenary of the armistice that ended World War I, the chain of memory that binds Musser’s family — and all of Europe — is growing brittle.

The anniversary comes amid a feeling of gloom and insecurity as the old demons of chauvinism and ethnic division are again spreading across the Continent. And as memory turns into history, one question looms large: Can we learn from history without having lived it ourselves?

In the aftermath of their cataclysmic wars, Europeans banded together in shared determination to subdue the forces of nationalism and ethnic hatred with a vision of a European Union. It is no coincidence the bloc placed part of its institutional headquarters in Alsace’s capital, Strasbourg.

But today, its younger generations have no memory of industrialized slaughter. Instead, their consciousness has been shaped by a decadelong financial crisis, an influx of migrants from Africa and the Middle East, and a sense that the promise of a united Europe is not delivering. To some it feels that Europe’s bloody last century might as well be the Stone Age.

Yet World War I killed more than 16 million soldiers and civilians, and its legacies continue to shape Europe.

“The war to end all wars” set the scene for an even more devastating conflict and the barbarism of genocide. Churchill, Britain’s legendary wartime leader, thought of 19141945 as one long war.

“Those who fail to learn from history are condemned to repeat it,” he said in 1948.

Chancellor Angela Merkel of Germany, whose decision to welcome more than 1 million migrants to Germany in 2015 first became a symbol of a liberal European order, then a rallying cry for a resurgent far-right, said the jury is still out on whether Europe will heed the lessons of its past.

“We now live in a time in which the eyewitnesses of this terrible period of German history are dying,” she said. “In this phase, it will be decided whether we have really learned from history.”

Indeed, the last World War I veteran died in 2012. And the number of those who experienced World War II and the Holocaust is rapidly shrinking, too.

Now as then, Europe’s political center is weak and the fringes are radicalizing. Nationalism, laced with ethnic hatred, is gaining momentum. Populists sit in several European governments.

In Italy, a founding member of the EU, Matteo Salvini, the nationalist deputy prime minister, has turned away migrant boats and called for the expulsion of Roma. Prime Minister Viktor Orban of Hungary speaks of a “Muslim takeover” and unapologetically flaunts his version of “illiberal democracy.”

“In 1990, Europe was our future,” he has said. “Now, we are Europe’s future.”

After World War II, the EU sought to prevent anything like it from happening again by gradually creating a common market, a common currency, a passport-free travel zone and by pooling sovereignty in a number of areas.

But on Sunday, standing next to Merkel and her host, the fiercely pro-European French president, Emmanuel Macron, will be a number of nationalist leaders who would like nothing more than to pull the EU apart — among them President Donald Trump, President Vladimir Putin of Russia and President Recep Tayyip Erdogan of Turkey.

Historians guard against drawing direct parallels between the fragile aftermath of World War I and the present, pointing to a number of notable differences.

Before World War I, a Europe of empires had just become a Europe of nation states; there was no tried and tested tradition of liberal democracy. Economic hardship was on another level altogether; children were dying of malnutrition in Berlin.

Above all, there is not now the kind of militaristic culture that was utterly mainstream in Europe at the time. France and Germany, archenemies for centuries, are closely allied.

“What is being eroded today, is being eroded from a much higher level than anything we had ever achieved in Europe in the past,” said Timothy Garton Ash, professor of European history at the University of Oxford.

Still, Garton Ash sees 1918 as a warning that democracy and peace can never be taken for granted.

“It’s a really sobering reminder that what seems like some sort of eternal order can very rapidly collapse,” he said.