(Much of the material in this section is adapted with permission from the Book of Our Heritage by Rabbi Eliyahu Kitov.)"Tu B'Av" - The Fifteenth of Av
Nowadays, on the Fifteenth of Av, we observe a partial holiday; we don't say "Tachanun," a daily plea for Divine mercy, on the day itself, nor even in the Afternoon Service of the day preceding the fifteenth, similar to a full-scale holiday. Bride and groom also do not fast if the fifteenth is the day of their marriage.
These customs commemorate many happy events which occurred at various times over the history of the Jewish People. Some of these events were associated with the Temple; in the present temporary absence of the Temple, the degree of observance is (temporarily) somewhat diminished. A partial listing follows:
The last Mishnah in Masechet Taanit says, "There were no holidays so joyous for the Jewish People as the Fifteenth of Av and Yom HaKippurim, for on those days, daughters of Yerushalayim would go out dressed in borrowed white clothing (so that they would all look the same).
The King's daughters would borrow from those of the High Priest. Daughters of the High Priest would borrow from the Assistant High Priest's daughters; daughters of the Assistant would borrow from the daughters of the Priest designated to lead the People in times of War, the Kohen Anointed for War's daughters would borrow from the daughters of the Ordinary Priest. And the daughters of the rest of the Jewish People would borrow from each other, so as not to embarrass those who didn't have."
"And the daughters of Jerusalem would go out and dance in the vineyards located on the outskirts of the city. And everyone who didn't have a wife would go there." (Notice the relative lack of concern about controlling the situation when the opposite sexes are mixed, perhaps because the recent fast (in the case of Tu B'Av) and the fast on that very day in the case of Yom Kippur, have triggered a sense of self-control, which would not ordinarily necessarily be present.)
"And what would they say?"
"Young man, lift up your eyes and choose wisely. Don't look only at physical beauty - look rather at the family - 'For charm is false, and beauty is vanity. A G-d - fearing woman is the one to be praised...' ("Mishlei"/Proverbs 31:30)"
This focus on women and on marriage in the celebration of the day is based on two enactments which were made on the Fifteenth of Av, in favor of women:
The Torah tells us in Parshat Pinchas of the complaint to Moshe of the daughters of one Tzelafchad regarding the seeming inequality in Jewish Law, in the case where a man dies without sons, that his daughters seem to be bypassed in the chain of inheritance with regard to acquiring property in the Land of Israel (Some commentators suggest, based on this complaint, that if the "Meraglim" (Male Spies) had been "Meraglot" (Female Spies) there would have been no problem, because women have a greater love for the Land of Israel than men, and would never have slandered it). Hashem "steps in," so to speak, and informs Moshe that the daughters should not be excluded in favor of the sons, but that the daughters must be required to marry within their tribe.
This limitation on the marital prospects of Jewish woman was lifted once the Jewish People actually were settled in Israel; and it was lifted on the Fifteenth of Av.
Another case where a limitation on Jewish women was lifted on the Fifteenth of Av came in the Period of the Judges, in the wake of a punishment directed against the Tribe of Benjamin. The last chapters of the Book of Judges, which deals with the period of time approximately 1395 B.C.E. (Before the Common Era) - 1060 B.C.E.), the earliest period in the settlement of the Jewish People in the Land of Israel, described in that Book as basically a period of weak central control, when "there was not yet a king in Israel" (Shoftim 19:1), and "a person would and could do whatever he wanted to do," tell the story.
An account is found there of the Tribe of Benjamin acting in accordance with the description assigned it by the father Yaakov as a "wolf which tears its prey" (Bereshit 49:7; this is certainly not a complete description of the characteristics of that Tribe, because it was in their section of the Land of Israel (along with the Tribe of Yehudah) where the Holy Temple would be built). In any case, a man and a woman traveling in the area of Benjamin were taken in as a neighborly gesture by an elderly man. The Binyaminites acted in a manner indistinguishable from the manner in which the residents of Sodom greeted the guests of Lot, (Bereshit 19:1-10) except that in this case, the victims were defenseless human beings and not angels, with super- powers. In short, the woman was abused and killed by the men of the Tribe of Benjamin.
The reaction of the other Tribes was to make Civil War against Benjamin, and to enact that none of their daughters would be allowed to marry a man from that tribe.
But the enactment which prohibited a Jewish girl from marrying a man from the Tribe of Binyamin, like the earlier enactment against the orphan daughter of a man who died without sons marrying outside her own tribe, was cancelled at a later time, on the Fifteenth of Av.