At Noyon, executives tried to play the globalization game. In 2003, they opened a factory in Sri Lanka. Like Desseilles, Noyon was still making expensive Leavers lace for high-end lingerie clients, and hoped the production in Sri Lanka would improve margins.

It didn’t stop the bleeding. With around 800 workers in Calais, representing 60 percent of Noyon’s costs, revenue kept eroding.

Noyon laid off hundreds of employees, many of whom had spent their lives in the factories. “It hit all types of workers,” said Henri-Philippe Durlet, the general director of Noyon. “It was people who designed patterns, threaded bobbins, cut lace, maintained the machines, as well as drivers and customs officers who had less to inspect.”

As losses mounted, Noyon filed for bankruptcy last September and was on the verge of closing until a group of French lingerie makers swooped in to invest, wanting to protect their high-quality supply. Today, with just 170 employees, it is the largest lace factory in town.

The only way it can keep a competitive edge, Mr. Durlet said, is by maintaining the exquisite design and quality of French lace that artisans have perfected for decades.

Desseilles faced a similar fate, exacerbated by French labor laws. In 2011, facing what Michel Berrier, an owner, called “catastrophic losses,” Desseilles went into receivership to shed nine of its remaining 74 workers in a bid to survive.

But five employees, among them protected union leaders, sued to be reinstated. In 2015, a court ordered Desseilles to rehire them with back pay and damages, a cost of nearly one million euros. With debts of €600,000, it was money Desseilles did not have.

The company was forced into bankruptcy. “Globalization isn’t the only reason we ran into trouble,” said Mr. Berrier, surveying his near-empty factory floor. “The French labor laws put the last nail in the coffin.”

Ms. Le Pen’s National Front party issued a news release blaming cheap Chinese competition and the French labor code for endangering Desseilles.

Yet it was a Chinese investor, Hangzhou Yongsheng Group, that rescued the company, acquiring it in 2016.

Since then, Yongsheng, which runs textile and investing companies in Asia, has increased productivity, installing a bright new LED system that allows employees to easily identify flaws, and grouping Leavers machines closer together so that one employee can work several looms at once. Yongsheng also added new looms, and linked employee pay to production.

“‘Made in France’ matters — the expertise is here,” said Cloris Li, Yongsheng’s manager in France, who wants to start an Asian luxury label using French-made lace. “I hope I can bring a brighter future to Desseilles.”

With the factory humming again, Mr. Berrier hired five new employees, and hopes to obtain seven more.

Even there, the French system can provide disincentives. When he tried to hire a lace maker whom Noyon had laid off, he said, the man told him he was collecting so much of his old salary through unemployment, he saw no point in working.

Disappearing Jobs

The last of the lace makers are relieved to have jobs, but many are nostalgic for the days when French lace was king. Most have family ties to the factories that go back for generations.

“I learned how to string a bobbin when I was 11,” said Sonia Rengot, 47, a lace maker at Noyon for over 30 years. “Everyone in Calais had someone in the business.”

Today, when she walks around town, she can tell just by looking in a shop window whether the lace on a dress was made in Asia or in Calais.

Jean-Philippe Lenclos, 50, has worked the lace machines at Desseilles for 30 years. “We’ve seen our colleagues leave one after another,” he said. “I’m the last one: My three children are teenagers, but none of them wants to do what their father is doing.” He added that the younger generation has grown up hearing only about layoffs.

Even as they hope the factories will stay afloat, the lace makers seem aware that the damage to France’s lace industry — and to other manufacturers around the country — is permanent. On the streets of Calais, no one really expects the factories to return.

Mr. Durlet, the Noyon executive, does not think either of the presidential contenders is capable of reversing France’s industrial decline. Not Mr. Macron, with his pledges of keeping France open to globalization. Not Ms. Le Pen, with her vision of hard protectionism.

“She talks about closing borders, but what will that serve?” Mr. Durlet asked. “Nothing. “

But for some on the factory floor, Ms. Le Pen’s promises have struck a chord.

“People are so disappointed that they will go vote for Marine Le Pen out of frustration,” said Renato Fragoli, a 23-year Desseilles veteran who led an employee group called the Forgotten, which backed Yongsheng’s bid to keep the factory from closing.

“It’s truly sad,” said Mr. Fragoli, recalling the scores of longtime workers who left the factory amid waves of layoffs. “But I can understand them. The jobs have disappeared.”