The summer months are finally upon us and there's lots of vacation and freedom. But we must not forget that during this time there are two fasts. That of the 17th of Tamuz ( Sunday July 8) and the 9th of Av (Sunday July 9. These days commemorate many terrible tragedies that happened to the Jewish people.

The 17th day in the Jewish month of Tammuz, Jews the world over fast and lament
Going all the way back to Biblical times, Moses descended Mount Sinai on this day and, upon seeing the Golden Calf broke the first set of Tablets carrying the Ten Commandments (Shemot 32:19, Mishna Taanit 28b).

In the First Temple Era: The priests in the First Temple stopped offering the daily sacrifice on this day (Taanit 28b) due to the shortage of sheep during the siege and the next year 3184 (586 BCE), the walls of Jerusalem were breached after many months of siege by Nebuchadnezzar and his Babylonian forces.

In Melachim II 21:7 we find that King Menashe, one of the worst of the Jewish kings, had an idol placed in the Holy Sanctuary of the Temple.
The Talmud, in Masechet Taanit 28b, says that in the time of the Roman persecution, Apostomos, captain of the occupation forces, did the same, and publicly burned the Torah - both acts considered open blasphemy and desecration.
These were followed by Titus and Rome breaching the walls of Jerusalem in 3760 (70 CE)
and Pope Gregory IX ordering the confiscation of all manuscripts of the Talmud in 4999 (1239).

In later years this day continued to be a dark one for Jews. In 1391, more than 4,000 Jews were killed in Toledo and Jaen, Spain and in 4319 (1559) the Jewish Quarter of Prague was burned and looted.

The Kovno ghetto was liquidated on this day in 5704 (1944) and in 5730 (1970) Libya ordered the confiscation of Jewish property.

Other interesting occurrences on this day include Noach sending out the first dove to see if the Flood waters had receded, (Bereishit 8:8) in 1650 (2100 BCE); Moshe Rabbeinu destroying the golden calf, (Shemot 32:20, Seder Olam 6, Taanit 30b - Rashi) and then ascending back up Har Sinai for the second time where he spent the next forty days pleading for forgiveness for the sin of the golden calf, (Shemot 33:11, Rashi).

9th of Av

Seven tragedies befell us on the ninth of Av making this (besides Yom Kippur) the most serious fast of the Jewish year.
1. The sin of the spies caused Hashem to decree that the Children of Israel who left Egypt would not be permitted to enter the land of Israel;
2. The first Temple was destroyed;
3. The second Temple was destroyed;
4. Betar, the last fortress to hold out against the Romans during the Bar Kochba revolt in the year 135, fell, sealing the fate of the Jewish people.
5. One year after the fall of Betar, the Temple area was plowed.
6. In 1492, King Ferdinand of Spain issued the expulsion decree, setting Tisha B'Av as the final date by which not a single Jew would be allowed to walk on Spanish soil.
7. World War I – which began the downward slide to the Holocaust – began on Tisha B’av.

Destruction of the two Temples
Tisha B'av at OU.org
A dvar Torah on 17th Tamuz