Summary of 3 Weeks & 17th of Tamuz
The fasts of Gedalia, the 10th of Teves, the 17th of Tamuz, and Tisha B'Av, were ordained to commemorate the destruction of the 1st and 2nd Batei Mikdash (Temples). Beginning with the 17th of Tamuz - July 1st and culminating on Tisha B'Av - July 22 is a period of mourning. As legislated by the Talmud and amplified by our customs, the degree of mourning becomes more intense as we approach Tisha B'Av.
The laws of the 3 Weeks extend from July 9; the 17th of Tamuz, until after Tisha B'Av; August 5. Our Minhagim (custom) is not to shave or take haircuts during this three-week period, and it applies to men and women. Marriages are not performed and it is forbidden to rejoice with music and dance. The custom is to refrain from listening to any music, or to attend any public entertainment. Occasions necessitating the Bracha of Shehechiyanu, such as wearing new clothes or eating a new fruit should be avoided during the Three Weeks. Purchasing new clothing is also not permitted unless there are extenuating circumstances. Please refer all such concerns to your local rabbi.
On the 17th of Tamuz, the following 5 (five) tragedies befell the Jewish People. In commemoration of these events Chazal (our Rabbis) ordained a public fast day on this day:
1. Moshe returned from Mt. Sinai and witnessed the Golden Calf. Moshe broke the first Luchot.
2. From the day that the Mizbeach (altar) was inaugurated in the desert (2449), offerings were sacrificed every single day for 890 years. During the fall of the first Bait Hamikdash, there were no more sheep to sacrifice due to the hunger, and the daily offerings were stopped.
3. During the fall of the second Bais Hamikdash, the Romans breached the walls of Yerushalayim. At the destruction of the 1st Bais Hamikdash, the walls were breached on the 9th of Tamuz. The fast of the 17th commemorates both occasions.
4. The Talmud in Taanis recounts that in 2610, right before the story of Channukah, Apustomus, a Syrian governor, publicly burned a Sefer Torah.
5. In 3228, during the 1st Bait Hamikdash, King Menashe placed an idol in the Bait Hamikdash. During the era of the 2nd Bait Hamikdash, Apustomus did the same.