After World War II concluded in Europe in 1945, David de Csepel’s family embarked on a new battle: the retrieval of their esteemed art collection, stolen by the Nazis.

Over the past 80 years, the family has pursued numerous legal battles globally to recover the paintings, tapestries, and Renaissance furniture that belonged to De Csepel’s great-grandfather, Baron Mór Lipót Herzog.

Recently, their focus has shifted to reclaiming 28 paintings, including three works by El Greco, which they estimate to be worth $100 million. These pieces are currently held in public institutions across Hungary, specifically three museums and a university in Budapest.

For more than 15 years, the family has been engaged in legal proceedings against Hungary in U.S. courts. They now hope that new provisions in significant legislation pending before Congress might assist them and other American victims of Nazi looting in recovering their family treasures.

According to legal experts, proposed amendments to the 2016 Holocaust Expropriated Art Recovery (HEAR) Act could potentially allow U.S. courts to hear cases involving foreign expropriation.

This bipartisan bill, which received unanimous approval in the Senate last December, aims to eliminate barriers like time limits, enabling victims of Nazi art theft to pursue restitution through litigation.

“I’m very frustrated,” said De Csepel, 60, the Altadena-based executive director of the Alliance for SoCal Innovation, a nonprofit that supports start-ups.”I grew up with my grandmother telling me stories about how Nazis came into their home in Budapest and just took paintings off the wall. And we are still fighting to get them back.”

Last month, the DC Circuit Court, which denied the family’s most recent appeal, signaled the need for Congress to pass the HEAR Act legislation in order to allow heirs to use US courts to litigate for the return of their art.

‘”The Herzogs were innocent victims of war and genocide, some of the millions of people for whom no measure of justice has ever been granted,” the court said in its decision.

“Their family heirlooms now hang on the walls of public institutions in Hungary that, to date, have shown no real interest in atoning for the depredations of that country’s World War II−era government.

“The only question we face today, however, is not whether these plaintiffs deserve justice — they surely do — but whether Congress has granted US courts the jurisdiction to provide it. “

Alycia Benenati, the lawyer for the family, agrees: “The pending HEAR Act amendments are critical for the Herzog family and other victims of Nazi persecution,” she told The Post. 

De Csepel is the great grandson of Herzog, a prominent banker who died in 1934, upon which point his art collection was passed to his family.

He had assembled Hungary’s largest private art collection, with more than 2,500 works by artists including Doménikos Theotokópoulos — better known as El Greco — Claude Monet, Paul Gauguin and Pierre-Auguste Renoir.

Much of that art is scattered among museums and private collections around the world, including in Russia’s Hermitage museum, the family says.

During the Hungarian Holocaust, which began in 1944, more than 500,000 Jews were killed. Some members of the Herzog family were able to escape to other countries and, at first, hide a large part of their collection in the basement of a family factory. However, those artworks were discovered and seized by Adolf Eichmann, who headed up the special Nazi task force that deported and executed Jews in Hungary.

After the war, the Soviet communist regime which took over the country took possession of the art that the Nazis left behind and spread it across their realm.

“Right when the Berlin Wall fell we took up this cause with members of Congress trying to get Hungary  to do the right thing,” De Csepel told The Post.

But Hungary has long maintained that the Herzog heirs no longer own the art and that compensation was paid in 1973 that resolved outstanding claims — a situation disputed by the heirs and their attorneys.

Now, the family and other victims of Nazi theft are putting their hopes on the extension of the HEAR Act, which was first unanimously passed by the House and the Senate in 2016.

US Rep. Laurel Lee (R. Fla.) sponsored the current legislation. “Recent court interpretations have prevented families like this one from even having their day in court,” Lee told The Post. “That was never the intent of the law. My legislation restores that intent.”

Today, there are currently more than 100,000 works of art looted by the Nazis that have not been recovered, according to reports.

“We must confront this unacceptable and repugnant reality, which continues to allow entities and individuals to profit off the Jewish people’s pain,” said Rep. Jerry Nadler (D. NY), who was one of the original sponsors of the law. “Justice must not be denied due to procedural technicalities and legislative sunset provisions.”

Holocaust survivor Louise Lawrence-Israels, President of the Miami-based Holocaust Survivors’ Foundation USA, urged the House to pass the legislation.

“Congress must fix this law,” she said. “Nazi Germany perpetrated murder and theft on an incomprehensible scale, both directly and through Allied, occupied, and collaborating governments. Protecting Germany and other governments holding looted art today, based on abstract academic theories, is an insult to history and morality.”