Last May, a painting stolen by a Nazi soldier from the Lubomirski Palace during World War II was repatriated to Poland. The painting, attributed to Alessandro Turchi, a 17th-century Italian artist, was pulled from a Tokyo auction after it was spotted by a Polish official.

Last October, the F.B.I.’s art-crime team handed a painting by Johann Franz Nepomuk Lauterer, an 18th-century Viennese artist, over to the German Consulate in Chicago. An American soldier had stolen the painting from the Bavarian State Painting Collections, in Munich, in the 1940s.

The soldier’s nephew had contacted Christopher A. Marinello, the founder of Art Recovery International, an organization that traces stolen art, and said he wanted to return a painting that his uncle had brought home from Germany.

Madonna and Child, by the Baroque painter Alessandro Turchi, which was repatriated to Poland after having been looted by Nazis.

Then there is a watercolor by Eduard Gaertner, a German artist. In the last days of the war, a British soldier took it from Hitler’s Reich Chancellery, and he sent it back to the Museum of Prints and Drawings, in Berlin, in 2021. An art dealer had spotted it in the catalogue of an auction house in Nottingham, England.

“Almost everybody stole,” says Agnes Peresztegi, an expert on looted art and former director of the Commission for Art Recovery, a nonprofit founded by Ronald Lauder. “The German soldiers did it, the Russians did it, the Americans did it, and so did the British, the French, and the Italians.”

Eduard Gaertner’s Der Leipziger Platz in Berlin, taken from the Germans by a British soldier during the war.

Marinello tells me that he gets calls from veterans or their heirs at least once a month. “The reason much of it is happening now is that the World War II generation is now getting to the age where they want to have a clear conscience,” he says. “In some cases, it is the heirs or the estate attorneys who want to see certain wrongs made right. I’ve returned more than 25 items in the last five years—mostly paintings, several illuminated manuscripts, rare books, and a few pieces of porcelain.”

Marinello continues: “For the last 20 or 30 years I’ve been getting calls—and they have been increasing lately—from people saying they have a Nazi stolen painting with a swastika on the back and they think this will increase its value when actually the painting and the swastika are fake. Or they will tell me they have something that was in Hitler’s collection. It’s all garbage. I see a lot of this stuff coming from the United States, Turkey and online.”

“Almost everybody stole. The German soldiers did it, the Russians did it, the Americans did it, and so did the British, the French, and the Italians.”

The Monuments Men and Women Foundation has returned more than 40 stolen objects, according to Robert M. Edsel, who in 2007 founded the nonprofit that honors the men and women who rescued art during World War II. Among the works recovered are drawings from the National Museum in Warsaw, a Flemish tapestry, and paintings from the collection of Queen Victoria.

“There’s a lot more to be found in the United States,” Edsel says, “not just by soldiers who brought objects home but hundreds of thousands of European immigrants, including former German soldiers, who brought their belongings to the United States. During the war, many things were mailed home or brought home by soldiers on all sides.”

Restitution experts say that although works stolen in the 1940s by soldiers and civilians are being returned, the field is insufficiently investigated, generally well hidden, and requires significant research to find the thousands of paintings, porcelains, rare books, gold, silver, and other objects still in private hands in many countries.

“Although most of the attention has been on looted art in museums and state collections, there are enormous numbers of stolen artworks—tens of thousands of paintings are unaccounted for—and other objects unaccounted for,” says Wesley A. Fisher, director of research of the Conference on Jewish Material Claims Against Germany and the World Jewish Restitution Organization. “The objects are in the possession of individual soldiers and individual civilians who took objects when they had the opportunity.”

Last Tuesday, a group of nations led by the United States presented clarifications to guidelines created by the Washington Principles in 1998 to accelerate restitutions worldwide. “These best practices more precisely define what is considered Nazi-looted art,” said Secretary of State Anthony J. Blinken.

“The World War II generation is now getting to the age where they want to have a clear conscience.”

Many of the returned objects have little value monetarily, according to looted-art experts. Carola Thielecke, general counsel of the Prussian Cultural Heritage Foundation, a German federal-government organization that oversees museums, libraries, archives, and research institutions in and around Berlin, tells me that “there is at least a trickle of these pieces that come back to us year after year.”

American soldiers retrieving artworks stolen by Göring, 1945.

She adds, “Often, these have come onto the art or antiquarian market. Sometimes, art dealers contact us. In other cases, one of our staff sees a piece in a dealer’s catalogue or auction announcement, and we contact the dealer or auction house. Mostly, it is impossible to trace the history back very far because pieces have changed hands several times since the war and the current owner only obtained them 10 or 20 years ago.”

“The soldier gave it to another soldier, who gave it to a clergyman, who gave it to someone else, and it eventually came to us for sale.”

In the last five years, the Art Loss Register, which has a database of 700,000 lost or stolen works, has identified three works that were directly stolen either by German soldiers or civilians from the Führerbau, Hitler’s personal office building in Munich, according to Amelie Ebbinghaus, the company’s director of provenance research.

“In these cases, the consignors to auctions are not descendants of the thieves but had acquired the works later in the market and were unaware of their problematic past,” she says. “The works are Dutch, Flemish, or Italian but of lower value.”

Fisher, of the Claims Conference, believes recent events indicate that the return of more objects could be expected. “There has been a development of moral awareness in public museums in a number of countries, awareness that has been extending to colonial or other sorts of seizures,” he says. “Eventually, it is to be hoped, such moral awareness will spread to private citizens.”

Milton Esterow was the editor and publisher of ARTnews from 1972 to 2014. He currently contributes to The New York Times, The Atlantic, and Vanity Fair