PARIS.- The Nazis stole thousands of artworks from Jewish families during World War II and their restitution has been a slow process, involving legal battles, complex searches and some stunning finds.

After a French appeals court ruled Tuesday that a painting by impressionist master Camille Pissarro must be returned to the family from which it was stolen, here is some background.

Plunder and rescue
The art plundered by the Nazi regime was intended to be resold, given to senior officials or displayed in the Fuehrermuseum (Leader's Museum) that Adolf Hitler planned for his hometown of Linz but was never built.

Just before the end of the war, the United States dispatched to Europe teams of experts -- museum directors, curators and educators -- to find, protect and rescue cultural treasures.

Known as the Monuments Men, they were honoured in a 2014 George Clooney film of the same name.

Their efforts enabled the return of most of the looted works to their owners soon after the end of the war.

But out of 650,000 stolen pieces, about 100,000 had not been returned by 2009, according to figures released at the Holocaust Era Assets Conference in the Czech Republic that year.

Secret records
Works seized by the Nazis in France were stored at the Jeu de Paume site in Paris, before being shipped to Germany.

Thanks to secret notes of art historian Rose Valland, about 60,000 were recovered and three-quarters returned before 1950, according to a 2013 report to the French Senate.

Of the remaining "orphaned" pieces, some were sold and more than 2,000 were accorded a special status under which they were provisionally entrusted to museums.

Some were exhibited from 1950 to 1954, but then, "for 40 years, nothing happened", said the 2000 Matteoli report on the looting from French Jews.

New impetus
After a period of inertia in the context of the Cold War, the process was revived in the 1990s after the online publication of databases such as The Art Loss Register.

In December 1998, 44 countries signed the Washington Declaration that committed them to stepping up efforts to return stolen pieces to their pre-war owners or their heirs.

In 2016 the US Holocaust Expropriated Art Recovery Act lengthened the time limit for lodging a restitution claim.

The Klimt affair
In one of the biggest cases involving art stolen by the Nazis, five masterpieces by Gustav Klimt were caught up in a legal battle between a descendant of the Jewish family from which they were taken and Austria's Belvedere Museum.

They included two stunning portraits of Adele Bloch-Bauer, completed with gold leaf.

American heiress Maria Altmann said they belonged to her uncle, Adele's husband, and the pieces were returned to the family in 2006.

The story was adapted into the 2015 film "Woman in Gold".

A spectacular find
In 2011 a tax raid on a Munich flat uncovered hundreds of priceless paintings stolen by the Nazis, including works by Picasso and Matisse.

The flat belonged to octogenarian Cornelius Gurlitt whose father had been tasked with selling the pieces.

An additional 239 works were found at a house he owned in Salzburg, Austria.

When Gurlitt passed away in 2014, he left his collection to the Museum of Fine Arts in Bern, Switzerland. Many of the pieces have since been subject to legal challenges across Germany.

Recent restitutions
In February 2018 France returned three paintings by the Flemish master Joachim Patinir, "Triptych of the Crucifixion", to the descendants of the Bromberg family who were forced to sell them as they fled the Nazis.

And in June, a Berlin museum said it had formally restituted a 15th century religious wooden sculpture to the heirs of the former owners, a Jewish couple who fled the Nazi regime.

The jewel of gothic art remains in the museum under an accord struck with the heirs.


© Agence France-Presse