correct a previous mistake.
On the Tenth of Tevet, 2,500 years ago, Nebuchadnezzar began his siege of Jerusalem. There was little actual damage on that first day and no Jews were killed. The siege was a message to get the Jewish people to wake up and fix their problems. They failed, and the siege led to the destruction of the King Solomon's Temple. That is why the 10th of Tevet was such a tragic day and this needs to be corrected with fasting.