1. It Is a Fast Day Referenced in Zechariah

The 17th day of Tammuz, known as Shiva Asar BeTammuz, is one of four fasts that the Prophet Zechariah predicts will one day morph from sadness into joy and gladness. He refers to it as “the fourth fast”1 because it takes place in Tammuz, the fourth month of the Jewish year, counted from the springtime month of Nissan.

Read: Jewish Fast Days FAQ

2. Sephardim Announce It on the Shabbat Before

The Code of Jewish Law cites the Sephardic custom that on the Shabbat before this fast (as well as other lesser-known fasts2) the cantor announces when the fast will be observed.3

3. It’s When Moses Broke the Tablets

On Shavuot, 6 Sivan, Moses went up to Mount Sinai and G‑d communicated the 10 Commandments to the nation. The following day (7 Sivan), he went up once again and told the people he’d be back in 40 days. On what they believed was the 40th day, 16 Tammuz, the people became antsy and crafted a Golden Calf, which they worshipped the following day, Tammuz 17. Upon seeing their disastrous actions, Moses shattered the Tablets and begged G‑d for forgiveness.4

Read: What Was the Golden Calf?

4. The Daily Sacrifices Halted on This Day

During the time when the Hasmonean dynasty ruled Judea, Hyrcanus II (who served as High Priest) was briefly crowned king, before his brother, Aristobulus II, rose in rebellion. Hyrcanus took refuge in Jerusalem, and Aristobulus and his men surrounded the city, not allowing people or goods to enter or exit. An exception was made for two lambs, which were brought into the city every day to be sacrificed on the Holy Temple’s altar—one in the morning and one in the early afternoon. When this stopped, on 17 Tammuz5 the priests were forced to discontinue the daily sacrifices as no sheep could be found. (Some say that this happened during the siege before the destruction more than 100 years later.)6

Read: The Destruction of the First Holy Temple

5. The Romans Breached Jerusalem on This Day

In 69 CE,7 the Roman destroyers breached the walls of Jerusalem and began a period of burning, looting, murder, and mayham, which culminated with the Temple complex burning on 9 Av, three weeks later.

Read: Titus Breached the Walls of Jerusalem

6. It May Also Be When the Babylonians Broke Through

The prophet Jeremiah tells us that the Babylonians broke the walls of Jerusalem on 9 Tammuz (in 423 BCE).8 The Jerusalem Talmud and other sources9 maintain that the 17th of Tammuz was the date that the Babylonians breached the walls of Jerusalem on their way to destroy the first Temple.

How can both be true? The Talmud10 explains that due to the intense suffering and chaos that reigned at that time, the people became confused and Jeremiah actually recorded the wrong date.

Not satisfied with this answer?

Read: When Were the Walls of Jerusalem Breached?

7. It Commemorates Two Other Events

This fast day also commemorates two other, somewhat mysterious, events.

It was the day when Apostomus burned a Torah scroll and an idol was placed on the Temple altar. Historians have long debated when the Torah burning occurred: some maintain that Apostomos was a general during the Roman occupation of Israel, while others contend that he lived years earlier and was an officer during the Greek reign over the Holy Land. The nature of the idol placed on the altar is also shrouded in controversy: some say that this too was done by Apostomus, while others say it was done by King Manasseh of Judea.

See: Who Was Apostomus, Who Burned a Torah Scroll?

8. It Is Often on Sunday

Like the first day of Passover, 17 Tammuz can occur on Shabbat, Sunday, Tuesday or Thursday. When it falls on Shabbat, it is delayed until Sunday, as fasting is not permitted on Shabbat. This means that approximately 40% of the time it is observed on a Sunday.11

Read: On Which Days Do Jewish Holidays Begin?

9. The “Three Weeks” Begin on This Day

The three weeks between 17 Tammuz and 9 Av are marked by national mourning for the tragic events that happened at this time of year. We do not hold weddings, enjoy music, or cut our hair. The sadness intensifies in the final 9 days, which begin with Av 1, and are further increased on the actual week of 9 Av.

Read: 3 Weeks Laws and Customs

10. Noah First Released the Dove on This Day

The ancient rabbinic chronology, Seder Olam Rabbah,12 tells us that on 10 Tammuz Noah dispatched the raven from the window of the ark, only to have the bird return. Seven days later, on 17 Tammuz, he sent out the dove, who also returned since he could find no terra firma on which to land. The dove was sent out again seven days later, and this time returned with an olive leaf in his beak.

Read: Where Did the Dove Find the Leaf?

11. Rabbi Yitzchak Rappaport Passed Away

For centuries, the chief rabbi of Israel has been known as the Rishon Letzion (“First to Zion”). This designation has always been held by a Sephardic scholar (an Ashkenazic counterpart eventually developed as well). The only Askhenazi to ever hold this position was Rabbi Yitzchak Hakohen Rappaport, who was born in 1685 to Polish parents in Jerusalem and educated in the Sephardic yeshiva system. After serving as rabbi of Izmir, Turkey, for decades, he returned to Jerusalem where he was appointed Chief Rabbi. He passed away on 17 Tammuz, 5515 (1755).