'And it was in the ninth year of his reign, in the tenth month, in the tenth (day) of the month, that Nebuchadnetzar, King of Babylon came, he and all his hosts, upon Yerushalayim, and he encamped upon it and built forts around it. And the city came under siege till the eleventh year of King Tzidkiyahu. On the ninth of the month famine was intense in the city, the people had no bread, and the city was breached.' (Second Melachim 25).
We see then, that the tenth of Tevet - on which the siege of Yerushalayim began, was the beginning of the whole chain of calamities which finally ended with the destruction of the Beit Hamikdash.
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