Today, December 29, the tenth of Tevet marks the day that Jerusalem was attacked by Nebuchadnezzar, the Babylonian leader, in 3336 or 435 B.C.E. Thirty months later, in 3338, on the 9th of Tevet, the walls of Jerusalem were breached, and on the 9th of Av in the same year, the First Temple in Jerusalem was destroyed. The Jewish people were exiled in Babylon for 70 years.
On the tenth of Tevet, Jews traditionally fast, pray special prayers to commemorate the terrible events of the day and repent for the sins that led to the destruction. The tenth of Tevet has also become a “general kaddish day” for those who perished in the Holocaust, since it is impossible to determine, in many cases, when these people died.
Since Jews are still in exile (we are still awaiting the Jewish king, Moshiach, the rebuilding of the Temple on its site in Jerusalem and an era of complete peace), today is a good day to reflect on what we can do to make the world better, and to bring Moshiach, or the Messiah. The Lubavitcher Rebbe said that the best way to bring Moshiach is through acts of goodness and kindness. So, in addition to other observances, today is an appropriate day to give extra charity or to learn Torah with someone.
It is interesting to note, and not, I think, a coincidence, that Saddam Hussein was executed yesterday, a day before the Tenth of Tevet, since he called himself the next Nebuchadnezzar, and made unprovoked attacks on Israel during the first Persian Gulf war. His aim was to destroy Israel, and thank G-d, he was unsuccessful. Perhaps this sequence of events is meant to give us hope on this day of mourning that we will have nothing more to fear from our enemies and the Revelation of Moshiach will be at hand.