Shiva Asar bTammuz
The Mishnah in Ta’anit says that the fast of Shiva Asar b’Tammuz was instituted for five major tragedies that occurred on this day (Ta’anit 4:6). Let’s look at each one.
The Breaking of the First Luchot
Following the giving of the Ten Commandments, Moshe Rabbeinu went up Mount Sinai to receive the entire Torah on the seventh of Sivan. He returned forty days later, on the seventeenth of Tammuz, saw that the people had made the golden calf, and broke the first luchot (Ta’anit 28b). Even though we received the second set of luchot on Yom Kippur, we still mourn the loss of the first luchot since one was able to learn the spiritual depth behind the Torah much more easily through the first luchot than through the second luchot (see Siftei Chaim, Emunah u’Bechira pp. 355-356). The Gemara also tells us that had the first luchot not been broken, no Torah would have been forgotten from the Jewish People (Eiruvin 54a). This was, therefore, a tragic loss.
Discontinuation of the Tamid Offering
The Tamid offering was discontinued also on the 17th of Tammuz. The Talmud Yerushalmi says that as the destruction of the Beit Hamikdash neared, there weren’t any sheep for the Tamid offering because of the siege that surrounded Yerushalayim. Every day, the Jewish People sent gold to the Romans in exchange for two sheep, but on the 17th of Tammuz, in exchange for the gold the Romans sent pigs instead, which is how the Tamid offering was discontinued (Yerushalmi Ta’anit 4:5; see also Rambam, Hilchot Ta’anit 5:2).
Breaching of the walls of Yerushalayim
The wall surrounding Yerushalayim was breeched on this day, which eventually led to the destruction of the Beit Hamikdash three weeks later, on the 9th of Av. The Gemara says that this was only regarding the second Beit Hamikdash, since the pasuk in Sefer Yirmiyahu says that the walls were broken on the 9th — and not the 17th — of Tammuz, when describing the destruction of the first Beit Hamikdash (Ta’anit 28b).
A fast was instituted on the 17th of Tammuz, and not on the 9th of Tammuz, because the 17th of Tammuz corresponds to the destruction of the second Beit Hamikidash. The destruction of the second Beit Hamikdash is more agonizing than the first because it has not yet been rebuilt, while after the first destruction, the Beit Hamikdash was rebuilt seventy years later (see Tur and Beit Yosef, Orach Chaim 549).
According to the Talmud Yerushalmi, however, the walls surrounding Yerushalayim of both the first and second Batei Mikdash were broken on the 17th of Tammuz (Yerushalmi Ta’anit 4:5).
Burning of the Torah
Apostamus, who was a Greek official during the second Beit Hamikdash, burned the sefer Torah that Ezra had written. This was tragic, especially since this was the sefer Torah that everyone used to copy from in order to write a new sefer Torah. Another opinion holds that Apostamus burned all the sifrei Torah that he found, in order to abolish the Torah from Yisrael. (Tiferet Yisrael).
Idol inside the Sanctuary
An idol was placed in the sanctuary of the Beit Hamikdash on the 17th of Tammuz. There are varying views in the Talmud Yerushalmi regarding the timing of this event. One opinion says this was also done by Apostamus during the second Beit Hamikdash. Another opinion says it was done by Menashe, king of Yehuda, during the first Beit Hamikdash (see Yerushalmi Ta’anit 4:5).
Time for Teshuva
Obviously it is not a coincidence that these tragedies all took place on this day. Internally, this day, and the three weeks following, leading up to Tisha B’av, is a time of judgment for the Jewish People. Therefore, we fast to help us submit ourselves, and thereby come to do teshuva. In the words of the Rambam: We fast on days of calamities because it arouses our hearts and opens paths to repentance for us. It serves as a reminder of our wicked ways and those of our ancestors, which resemble our present ways, and which thereby brought these calamities on them and on us, so that through remembering these things we will return and fix our ways; as it says: They will confess their sins and their father’s sins (Hilchot Ta’anit 5:1). May we all merit seeing the time when these fast days turn into joyous days through the coming of the Mashiach and the rebuilding of the Beit Hamikdash speedily in our days.