The new month we are in TEVET
The text in II Kings (25:1-4) tells us that on the 10th day of the 10th month, in the ninth year of his reign, (588 BCE), Nebuchadnezzar, the Babylonian king, began the siege of Jerusalem. Three years later, on the 17th of Tammuz, he broke through the city walls. The siege ended with the destruction of the Temple three weeks later, on the 9th of Av, the end of the first Kingdoms and the exile of the Jewish people to Babylon. It can thus be considered part of the cycle of fasts connected with these events: Tzom Gedaliah (3rd of Tishrei); Shivah Asar B'Tammuz (17th of Tammuz) and Tisha B'Av (9th of Av).
The first mention of this fast appears in Zechariah (8:19) where it is called the "fast of the tenth month..." (counting from the month of Nisan, which was the first month in Biblical times). Other references to the fast and the affliction can be found in Ezekiel 24:1-2 (the siege); Jeremiah 52:4-6.The Tenth of Tevet - Asarah B'Tevet
According to tradition, as described by the liturgy for the day's selichot, the fast also commemorates other ignominious events that occurred throughout Jewish history on the tenth of Tevet and the two days preceding it:
On the eighth of Tevet, 246 BCE (year 3515 on the Hebrew calendar), during Greek rule of Israel during the Second Temple period, Ptolmey, Greek of Egypt ordered the Septuagint, the translation of the Hebrew Bible into Greek. This was seen as a meddling in religious affairs by Greek interlopers and a debasement of the divine nature of the Torah and a subversion of its spiritual qualities by packaging it for a gentile audience whose interest in it was academic instead of theistic.
Ezra the Scribe, the great leader who brought the Jews back to the holy land from the Babylonian exile and who ushered in the era of the Second Temple, died on the ninth of Tevet