PARIS — Early on a Thursday morning in July 1942, more than 4,000 police officers set out in pairs through the streets of occupied Paris, carrying arrest orders for scores of Jewish men, women and children. Within days, 13,152 people had been rounded up for deportation to death camps. No more than 100 would survive.

The mass arrests, the largest in wartime France, were planned and carried out not by the Nazi occupiers but by the French. That difficult reality, for years denied, obscured, willfully ignored or forgotten, is now increasingly accepted here, historians and French officials say, part of a broader reckoning with France’s uncomfortable wartime past.

The 70th anniversary of that dark episode — known as the Vel d’Hiv roundup, after the arena where many of those arrested were taken — has brought a flurry of commemorations this month, with official ceremonies, museum exhibits, wide news media coverage and an address by President François Hollande. Perhaps most telling, though, is a modest installation at the municipal hall of the Third Arrondissement in central Paris, where the national police are exhibiting for the first time the documents that record the operation in cold administrative detail.

For decades after the war, historians say, the police resisted a public accounting of their actions under the German occupation and the collaborationist Vichy government, restricting access to their archives as they struggled with the same tangle of pride, guilt and shame that marked much of French society. The police were especially reticent, said Tal Bruttmann, a scholar of the Vichy period, “because it was they who conducted the arrests.”