On the 2nd and 3rd of Av in the year 5702 from creation (1942 CE), more than 13,000 Jews were rounded up by French police and interred in the Vel' d'Hiv, an indoor bicycle stadium in the center of Paris. They were later transported to Auschwitz to be killed. Within days, the Vel' d'Hiv was cleaned up and ready for recreation.
In the summer of 1929, R. Yosef Yitzchak Schneersohn, sixth Rebbe of Chabad, visited the Land of Israel (the only Chabad Rebbe to do so—see link below). The stated purpose of the trip was to pray at the gravesites of the righteous individuals interred there. Among the cities he visited during his two-week-long stay were Jerusalem, Safed, Meron, Tiberias, Hebron, and Tel Aviv.
The Rebbe departed the Holy Land two days before the Arab riots of 1929, in which scores of Jews were massacred in Hebron and Jerusalem (see entry for 17 Av).
Links: Cause and Effect, Why Didn’t the Rebbe Ever Visit Israel?
During the “Nine Days" from Av 1st to the Ninth of Av, we mourn the destruction of the Holy Temple. We abstain from meat and wine, music, haircutting, bathing for pleasure, and other joyous (and dangerous) activities. (The particular mourning customs vary from community to community, so consult a competent halachic authority for details.)
Consumption of meat and wine is permitted on Shabbat, or at a seudat mitzvah (obligatory festive meal celebrating the fulfillment of certain mitzvot) such as a brit (circumcision), or a siyum celebrating the completion of a course of Torah study (i.e., a complete Talmudic tractate). The Lubavitcher Rebbe, of righteous memory initiated the custom of conducting or participating in a siyum on each of the Nine Days (even if one does not avail oneself of the dispensation to eat meat).
Citing the verse "Zion shall be redeemed with mishpat [Torah] and its returnees with tzedakah," (Isaiah 1:27) the Rebbe urged that we increase in Torah study (particularly the study of the laws of the Holy Temple) and charity during this period.
Links:
Nine Days laws and customs
Daily live siyum broadcasts
Learn about the Holy Temple in Jerusalem
Zion is redeemed by the study of Torah, and its captives through charitable deeds. (Isaiah 1:27)
Exile is more than a geographical circumstance. Even if every Jew lived comfortably in the Land of Israel, we might all still be in exile. Exile within our own land.
Exile is a state of being that we carry within ourselves. It is sustained by a cause and healed by healing its cause: The exile of the divine soul within each one of us, and the discord that stands between us.
Because we are spread over the entire globe, with our healing comes the healing of the entire world. With our return from exile, all things will return to their intended place in a grand harmony.
The return to Zion depends upon our return to our own souls within Torah, and peace and harmony in this world begins with acts of loving-kindness between each of us.