On 14 June 1940, the German army marched into Paris, which had been declared an "open city". On 16–17 July 1942, following German orders, the French police and gendarmes arrested 12,884 Jews, including 4,115 children, and confined them during five days at the Vel d'Hiv (Vélodrome d'Hiver), from which they were transported by train to the extermination camp at Auschwitz. None of the children came back. On 25 August 1944, the city was liberated by the French 2nd Armoured Division and the 4th Infantry Division of the United States Army. General Charles de Gaulle led a huge and emotional crowd down the Champs Élysées towards Notre Dame de Paris, and made a rousing speech from the Hôtel de Ville.

On what date did the German army declare Paris as an open city?