27 Nisan

1435- Jewish residents of Speyer, Germany, were expelled.

May 2, 1943- Warsaw Ghetto uprising. In the summer of 1942, about 300,000 Jews were deported from Warsaw to Treblinka. When reports of the mass murder in the killing center leaked back to the Warsaw ghetto, an organized resistance began forming, which managed to smuggle a modest chache of arms into the ghetto.

On the 14th of Nissan of 1943, the remaining 35,000 Jews in the Warsaw Ghetto (from an original 450,000) staged an organized uprising, and drove back the Nazis with a rain of bullets when they came to begin the final removal of all Jews. The Jewish resistance lasted 27 days. A heroic stand was made in an underground bunker under 18 Mila Street, where hundreds of fighters, including the 24-year-old leader of the uprising, Mordechai Anilevitch, met their death.

Although the Ghetto was burned to the ground by Iyar 3, a few stray survivors hid in the rubble and fired at the Nazis for two months longer. In tribute to the uprising, the Israeli government designated the 27th of Nisan as its official "Holocaust Memorial Day"; in many Jewish communities, the day is observed as an annual Holocaust remembrance day. Because of the halachic prohibition to conduct eulogies and other mournful events in the festive month of Nisan, the chief rabbinate of Israel, and many Jewish communities, observe the 10th of Tevet as a day to mourn and remember the six million, which include many whose yahrtzeit (date of passing) remains unknown.

May 3, 1951-  By a resolution of the Knesset [the legislature], Israel, this day was designated Holocaust Memorial Day, in commemoration of the martyred six million Jews and the fighters of the ghetto. (See above).