The history of Marshal Philippe Pétain's collaborationist regime is still a sensitive subject in France.
The French state's complicity in the deportation of 76,000 Jews was only officially recognised in 1995 by then-president Jacques Chirac and the state-run rail network, the SNCF, was forced to pay compensation for having transported Jews by a campaign in the US in 2014.
Now the Socialist government has authorised the opening of archives that were supposed to have remained officially closed for 75 years - five years early for the oldest ones.
Files dating from as late as 31 December 1960 are also covered by the ruling, as long as they relate to events that took place between September 1939 and May 1945.
Documents concerning the prosecution of war criminals in France, Germany and Austria and cases taken before military and maritime tribunals may now be viewed.
There some 200,000 documents in police archives alone.
They include records of the activities of the Special Brigades, who specialised in tracking down the "enemy within", mainly communists and other resistance fighters, and will make public reports of tailing suspects, records of interrogations and letters of denunciation.
But the documents are still subject to national defence secrecy rules, meaning that applications could be turned down by military and security chiefs.
Most of them have already been seen by specialists but a wider public can now consult them, which may lead to unpleasant surprises for some, according to historian Jean-Marc Bélière.
"I've seen people leaving the archives in tears," he told Le Figaro newspaper in 2010. "Because they'd found out the details of an arrest, an execution, a betrayal, for example. Some came with the idea that their grandfather had been in the resistance but discovered that was not exactly true."
Archives on another sensitive period of France's history, the Algerian war of independence, remain closed.