After having been allowed back into France in the year 1315 (after the expulsion in 1306 by Philip IV), the Jews were once again expelled from France by Charles IV, who thus broke the pledge made by his predecessors in 1315 that the Jews would be able to stay in France for at least 12 years.
During the Three Weeks, from 17th of Tamuz to the 9th of Av, we commemorate the conquest of Jerusalem, the destruction of the Holy Temple and the dispersion of the Jewish people.
Weddings and other joyful events are not held during this period; like mourners, we do not cut our hair, and various pleasurable activities are limited or proscribed. (The particular mourning customs vary from community to community, so consult a competent halachic authority for details.)
Citing the verse (Isaiah 1:27) "Zion shall be redeemed with mishpat [Torah] and its returnees with tzedakah," 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:
The Three Weeks
Rashi explains that Jacob was pained that he had to leave the promised land and descend to Egypt. And yet, G-d does not address the pain. Instead, He tells him not to fear.
“G‑d said to Jacob: Do not fear descending to Egypt…” (Genesis 46:3)
Apparently, unlike the fear, the discomfort needed to remain.
The same is true for us.
The pain is real. The fear is not.
The pain is real, because we are not in our true place. Nothing is in its true place. It is called exile. Exile of the soul.
The fear is not real—there is nothing to fear. Because no matter where we are, G‑d is there with us. For He is everywhere.
The only thing we have to fear is that we may no longer feel the pain. That we may imagine that this is our place after all.
For it is that pain of knowing we are in the wrong place that lifts us higher, beyond this place.