27 Nissan: Yom HaShoah
Holocaust Memorial Day - Special memorial prayers are said.
Work Restrictions: No restrictions on work.
Since 27 Nissan is a Friday this year, it is preponed to Thursday, 26 Nissan (May 1).
Warsaw Ghetto Uprising began on this day in 1943 and lasted 27 days, as Jewish fighters drove back Nazis with the small arms cache they had managed to smuggle and amass. Yom HaShoah v’HaGevura (Day of the Holocaust and of Courage) is observed on this day. Due to a prohibition on eulogies and mourning during the joyous month of Nissan, many communities mourn the victims of the Holocaust on Assara B’Tevet (Tevet 10) instead.
From Chabad:
Warsaw Ghetto Uprising (1943)
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 Nissan as its official "Holocaust and Bravery Day," and in many Jewish communities the day is observed as an annual Holocaust remembrance day. But because of the halachic prohibition to conduct eulogies and other mournful events in the festive month of Nissan, the chief rabbinate of Israel, and many Jewish communities, observe instead the 10th of Tevet as a day to mourn and remember the six million, which include many whose yahrtzeit (date of passing) remains unknown.
From OU.org
The Holocaust was arguably among the most fearsome tragedies that have befallen the Jewish People in its long history, in which six million Jews, fully one third of World Jewry, including one and a half million children, were murdered.
And the murderers were not a People who would normally be called "barbaric." On the contrary, the majority of the officers of the so-called Concentration "Camps" were medical doctors (!), or doctors of philosophy, or respected professionals. A degree of evil was exhibited which perhaps has never been exceeded in all of human history.
It is not true that the murderers' evil was unopposed. Tremendous bravery was exhibited by relatively small numbers of Jews and Gentiles, such as at the Warsaw Ghetto, where the Jewish Community acted in concert, and by hundreds of individuals whose efforts resulted in the saving of tens, even hundreds of thousands of lives.
Although the saving of a single life is comparable to the saving of an entire world, the dimensions of the tragedy vastly outweighed all attempts to avert it, and the sweet taste of the good deeds was indistinguishable against the bitterness of the evil.