In the year 3828 (68 CE) on the 17th day of Tammuz, Titus broke thru the walls of Yerushalayim. Three weeks later on the 9th day of Av, the 2nd Bais Hamikdash was destroyed. During that time period over one million men, women, and children were killed. After the Churban the Jewish people were exiled from our land and tormented by our oppressors. For close to 2000 years (this year 5777, will be 1949 years since the destruction) the Jewish people have been cast into the role of the "wandering Jew". Throughout our history we have been persecuted and even until this day we see much anti- Semitism. Our Chazal teach us, all the tragedies and oppressions the Jewish people have suffered throughout our history, has their roots in the period of Bein Hamitzarim. We observe every year the "Three Weeks" as a period of commemoration and national mourning over the loss of our homeland of Eretz Yisroel, Yerushalayim and especially of the Bais Hamikdash.
The Rambam [Hilchos Melachim 12:4] writes that the reason why neivim (prophets) and chachamim (sages) mourn for the loss of the Bais Hamikdash is not for the desire to live the glorious life of "the land of milk and honey" and so that the Jewish people the rulers of the world. Rather they mourn the fact that we do not have the liberty to completely devote ourselves to the study of Torah in order to merit Olam Haba. We long for the opportunity to become the best people that we can be; to perfecting ourselves like the opportunity our ancestors had.
There are five levels of aveilus (mourning) observed during the Hebrew calendar dates between the17th of Tammuz until the 10th day of Av [the day after Tisha B'Av]. This period is referred to as The Three Weeks. The closer to Tisha B'Av it is, the degree of mourning intensifies. The halachos being discussed here are exclusively for the 13 days from Shiva Asar B'Tammuz [17th of Tammuz] until Rosh Chodesh Av [which begins the period that is known as "the Nine Days"].
Chazal teach us that five tragic things happened to the Jewish people on Shivah Asar B'Tammuz; Moshe Rabbeinu broke the 1st luchos [when he saw the Jewish people serving the Golden Calf], the Kohanim were prevented by Nevuchadnezar's army from bringing the korban tamid [which was not brought again until the 2nd Bais Hamikdash], the walls of Yerushalayim were destroyed [which led to the destruction of the 2nd Bais Hamikdash], the Greek general Apastomus publicly burned a Sefer Torah, and an idol was placed in the Bais Hamidash (Mishnah Taanis 26b). Since these tragedies occurred on Shevah Asar B'Tammuz, Chazal designated this day as a public fast day (Shulchan Aruch 549:1 & Mishneh Berurah 549:2).
It is important to note, the Gemara makes no mention of the restrictions of any activities starting from the Three Weeks. The Gemara mentions that Chazal wanted to prohibit eating meat all year because of the destruction of the Bais Hamikdash, but they saw that the Jewish people would not be able to handle it (Gemara Bava Basra 60b). At some point in history, our Chazal instituted that there are restrictions starting from Shiva Asar B'Tammuz, which continue until after Tisha B'Av. However, it is clear that these restrictions were rooted in the Gemara.
Prohibited activities include; haircutting and shaving, joyful activities [such as music, singing, dancing, and weddings], reciting birchas she'hechiyanu [the blessing recited for buying new things], and other miscellaneous potentially dangerous activities, which we discussed in more detail in the upcoming weeks.