Ringelblum led a secret operation in the Warsaw Ghetto code-named "Oneg Shabbat" (Hebrew for "Sabbath delight"). They wrote diaries, collected documents, commissioned papers, and preserved the posters and decrees that comprised the memory of the doomed community. They had no illusions of their own survival. Their only hope was that the memory of the Warsaw ghetto would endure after them.
On the eve of the ghetto's destruction in the spring of 1943, when all seemed lost, the archive was placed in three milk cans amd metal boxes. Parts were buried in the cellars of Warsaw buildings. One container was found in 1946 and another in 1950, at 68 Nowolipki Street. It contained copies of several underground newspapers, a narrative of deportations from the Warsaw ghetto, and public notices by the Judenrat (the council of Jewish leaders established on German orders).
Despite repeated searches, the rest of the archive, including the third milk can, was never found.