Thousands of Algerians marched through Paris on the night of October 17, 1961, to protest a curfew that the police prefect had imposed on them alone, and the police put the march down with force. The official count at the time was three dead. Later estimates, from historians and from the survivors, run into the hundreds, and many of the dead were found in the Seine, where they had been thrown or had jumped. The full record was never made. It may never be.
The context was the war. Algeria was then fighting for independence from France, and the Front de Liberation Nationale, the FLN, ran the Algerian community in France, and the police, under Maurice Papon, had been given a free hand against it. The curfew of October, applied to Muslim Algerians only, was the spark, and the march was called to break it, peacefully, with families and children, and the police answered it as an uprising.
What happened that night was buried for decades. The newspapers reported the official figures, the bodies went into the river, and the state kept the records closed, and it was not until the 1980s and 1990s, with the work of historians and the testimony of survivors, that the scale of the killings became part of the public record. A plaque now marks the site, and the date is kept by the Algerian community as a day of mourning.
The episode reached the future. It lingered. Papon, the prefect who had ordered the repression, went on to a career in government and was convicted in 1998, in a separate case, for his part in the deportation of Jews during the occupation, and the questions about October 1961 were raised again at his trial. France has acknowledged the killings only in part, and the event stands between the two countries still.