France is opening up police and ministerial archives from the Vichy regime which collaborated with Nazi occupation forces in World War Two.
More than 200,000 declassified documents are being made public on Monday. They date from the 1940-1944 regime of Marshal Philippe Petain.
During the war the Vichy regime helped Nazi Germany to deport 76,000 Jews from France, including many children.
France is also opening files from its post-liberation provisional government.
The Vichy documents come from the wartime ministries of the interior, foreign affairs and justice, as well as the police.
Some of the archives relate to war crimes investigations conducted by the French liberation authorities after the defeat of Nazi Germany.
Speaking to French TF1 television news, historian Gilles Morin said the archives would probably shed new light on the arrest of Jean Moulin, a French Resistance leader who died after his capture and torture by the Nazis in 1943.
Police records and notes seized from French Resistance comrades will now add to the witness statements that researchers have relied on until now, Mr Morin said.
"There is also a demand from the children of deportees, and of those who were executed, who want to know - and that's a legitimate demand," he said.
Previously only researchers and journalists could see some archives, with special permission. But public access is provided after 75 years have elapsed, under French law - and that is now the case, for 1940-dated documents.
The current mayor of Vichy, in central France, told The New York Times that he was concerned about the enduring stigma attached to his city. It was where Petain - a World War One hero - established his collaborationist regime.
"There are many stories about this city, and then there's the truth," he said, "because that period was very complicated and has been incorrectly defining this city for too long."
Former French Resistance fighter Lucien Guyot told the paper that the Petain government "went far beyond the Germans' expectations, in particular with the deportation of 'foreign' Jews, including children, to concentration camps, and they chased us down with a vengeance".
"But it was the government's actions that were unforgivable, not this city's," he added.
In 1995, then French President Jacques Chirac officially recognised the French state's responsibility in the deportation of Jews.
"These dark hours forever sully our history and are an insult to our past and our traditions," he said. "Yes, the criminal folly of the occupiers was seconded by the French, by the French state."