The Talmud (Tanit 26) tells us that five tragedies occurred on the 17th of Tammuz and five occurred during the 9th of Av.
- The Sin of the Golden Calf. A mere 40 days after receiving the Torah at Mt. Sinai, a group of Jews created, and then worshipped a “Golden Calf”. Upon seeing this group joyously worshipping the golden image they created, Moses broke the two tablets (upon which the Ten Commandments had been engraved).
- The Cessation of Daily Offerings. During the First Temple Era, the daily offerings ended during the siege of Jerusalem, as unblemished sheep could no longer be obtained. As the breach of the wall did in the second Temple, this indicated that the end was near.
- The Walls of Jerusalem are Breached. As was common. Jerusalem was protected by walls that were strong and tall. On the 17th of Tammuz the Roman legion was finally able to break through the walls.
- The Torah is Burnt. Before the actual war, the Romans had enacted a number of harsh decrees and openly provoked the Jews. On one such occasion, Apostomus, a Roman general, publicly burnt a Torah Scroll.
- An Idol Was Placed in the Holy Temple. Although there is some debate in the Talmud regarding the exact circumstances, an idol was placed in the Sanctuary of the Holy Temple.