423- "And it came to pass in the twelfth year of our captivity, in the tenth month, in the fifth day of the month, a figure came to me saying: 'The city was conquered.'" Only now had the Prophet Ezekiel heard the news of the destruction of the Beit HaMikdash and of Yerushalayim's conquest by a foreign power, as recorded in the Book of Ezekiel (33:21). In Jewish law, a period of mourning (for example, upon the death of a loved one) can begin upon "hearing" the bad news. Some Talmudic commentators thus recommended that the 5th of Tevet be instituted as a public fast day.
1534- Roman Emperor Charles V ordered the auto-da-fe* of Harav Shlomo Molcho in Mantua, Italy.
December 31, 1791- The Pale of Settlement was instituted by Empress Catherine, limiting Jewish rights in Russia.
*Public announcement of the sentences imposed by the Inquisition, especially by burning at the stake.