BERLIN — If the origins of Germany’s tricolor flag are not widely known, that is because the banner is rarely displayed in a country still atoning for the crimes it carried out in the name of national pride. 

There may be a history lesson, then, and not just an electoral gambit, in the prominent use of black, red and gold in posters advertising Chancellor Angela Merkel’s bid for a fourth term in the federal election in September. Germany’s colors have appeared in previous modern political campaigns but more mutedly — and hardly ever to amplify so blunt an appeal to the national interest.

“For a Germany in which we live well and happily,” proclaims one poster.

Germans’ wary attitude toward patriotism and the idea of a national culture is decades old. But circumstances both global and domestic are forcing a reconsideration. As the country decides how it might serve as a custodian of the liberal international order, it is also sorting out how to integrate migrants who began arriving in enormous numbers in 2015. Both undertakings bear crucially on German values — and on the issue of whether a unified set of national principles even exists.   

“The question is really, ‘What’s the cement?’ ” said Arnd Bauerkämper, a professor of modern European history at the Free University in Berlin. “What should Germans have in common?”

One answer has come from Thomas de Maizière, Germany’s interior minister, who has championed the concept of “Leitkultur,” or leading culture, a term sometimes used as the conservative rejoinder to multiculturalism. 

“Strength and internal certainty about one’s own culture leads to tolerance with respect to other cultures,” he wrote this spring in Die Zeit, a weekly newspaper. 

The concept makes some on the left uneasy.

Efforts to define German culture are “often used to draw a line between us and others,” said Katharina Zimmermann, a 32-year-old who works in marketing in Berlin. She added: “It makes me shiver when I see a German flag.”

In June, Merkel herself took to the pages of Bild, the top-selling German tabloid, to answer the question, “What is German?” She gave a slew of answers including federalism and Oktoberfest.

[Here’s why Germany’s left has dwindling hopes of unseating Merkel]

Even lawmakers in Merkel’s center-right Christian Democratic Union disagree about whether such things, though widely regarded as national treasures, are grounds for pride.

“I wouldn’t say ‘proud,’ though I like to be German,” said Thomas Strobl, the party’s chairman in Baden-Württemberg, Germany’s third-largest state. More so, he said, he feels passionately about his region, as well as about Europe as a whole. 

Wolfgang Bosbach, another leading conservative lawmaker, had a different answer, noting that Germany was able to overcome “Nazi barbarism” to become one of the world’s most stable democracies. “I am proud of my country, yes,” he said.

The appeal to national feeling by Merkel’s campaign would hardly raise an eyebrow in the United States, or indeed in much of the rest of the world, where love of country is habitual, if not presumed. Flags express that devotion, and they encode history.

But Germany’s flag has a more complicated history than most. 

The use of black, red and gold — arranged in horizontal bands — predates the Nazi era. The design emerged in democratic movements for a unified Germany in the mid-19th century and first became the national flag in the short-lived Weimar Republic between the world wars. Discarded by the Nazis in favor of the black-white-red imperial tricolor and the swastika flag, today’s emblem was reintroduced in 1949. 

Despite its democratic associations, the flag has long been a source of discomfort, and it has been mostly confined to government buildings or else unfurled at specific moments of national jubilation, such as in 2006 when Germany hosted the World Cup.

Thomas Kleine-Brockhoff, director of the Berlin office of the German Marshall Fund of the United States, said attitudes have changed in some spheres.

“I don’t think other nations, or other sports fans, see Germans’ displaying their flag as aggressive; it’s just what everybody else does,” he said. “That wasn’t the case before.”

But the change hasn’t been reflected in politics, he said. At a 2013 election party, Merkel went so far as to take the flag from the hands of a colleague. 

“Her party won, not the nation,” Kleine-Brockhoff said. “For Americans, that’s hard to understand.”

The calculus appeared to shift, slightly, ahead of this year’s federal election.

Merkel’s campaign materials feature “the most prominent display of the color code ever,” said Thomas Strerath, head of the Hamburg-based advertising agency that developed the designs.  

Originally intended to fend off a challenge from the far-right Alternative for Germany, the color scheme is meant to appeal to patriotism, not nationalism, Strerath said. In internal papers, the agency settled on the concept of “falling in love again with Germany.”

 “Trump had been elected, [Rodrigo] Duterte in the Philippines and [Recep Tayyip] Erdogan in Turkey were tightening their grip,” Strerath said. “We realized that what they have in common is that they don’t come up with the best argument but instead address emotions. If we’re good at something in advertising, we’re good at addressing emotions, and we didn’t want to let the interpretation of what Germany means be the territory of the far right.”

Merkel, who meets with agency executives weekly, thought it was a slam-dunk, Strerath said.

Stephanie Kirchner and Alexandra Rojkov contributed to this report.

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