Beginning of "The Three Weeks"- a period of mourning for the destruction of Jerusalem and the Holy Temple, culminating in the fast of Tisha b'Av.
2267 BCE- On this day, Noah sent out the dove the first time to see if the waters of the Great Flood have receded; "But the dove found no rest for the sole of her foot and she returned
to the ark..." (Genesis 8).
The Talmud (Taanit 28b) lists five tragic events in Jewish history that occurred on the 17th of Tammuz, on account of which a fast was instituted on this day:
1) Moses came down from Mt. Sinai with the first stone tablets, inscribed with the Ten Commandments. Moses broke the tablets when he saw the people of Israel worshipping the Golden Calf (c 1476 BCE).
2) The walls of Jerusalem are breached in 586 BCE before the destruction of the First Temple and in 69 CE before the destruction of the Second Temple.
3) The daily sacrificial offering in the Temple was discontinued, three weeks before the Babylonians' destruction of the First Temple in 586 BCE.
4) King Menashe placed an idol in the holy of holies of the first Temple.
5) Apostomus, a Greek officer who ruled Israel before the destruction of the Second Temple, burned a Torah in public (63 BCE). According to some, it was he who placed the idol in the Temple at the same time.
The fighting in Jerusalem continued for three weeks until the 9th of Av, when the Holy Temple was set
aflame.
June 20, 1391- While the Jews of Toledo, Spain were commemorating the fall of the Temple, their Christian neighbors attacked. 4,000 Jews were massacred in Toledo, Spain, sparking pogroms in other Spanish Jewish communities, leading to widespread poverty and deaths. Rabbeinu Yehudah of Toledo, his wife (the daughter of the Baal Haturim), and his mother-in-law were killed. On Tisha B'Av 5252/1492, 101 years later, the extinction of Spanish Jewry was completed with the mass expulsion.
The Sages found a hint to the tragedies of the seventeenth of Tammuz in the story of Noah and the dove which took place on this day, as mentioned above. The dove's not finding a "resting place" alludes to the trials which the people of Israel, which are likened to a dove, experienced on this day many generations later.
July 4, 1776- The Declaration of Independence was announced in the new country of the United States of America.
July 12,1941- 4,000 Jews of the Bialystoker ghetto were shot and killed.
Several hundred Jewish women and girls were abducted from their houses, raped and shot by the Nazi SS during the night in Khotin, Ukraine.
July 21,1970- All Jewish property was confiscated in Libya.