July 31 586 BCE – 7 Av 3174
The biblical book of Kings records this date as the day the Babylonians set fire to the Temple and burned the city of Jerusalem. The book of Jeremiah (chapter 52 verse 12), however, claims it happened on 10 Av – a contradiction the sages of the Talmud reconciled by suggesting the fire was set on 7 Av and burned until the 10th of the month. The Second Temple was destroyed on 9 Av, the date chosen for the fast marking the destruction of both temples.
Woodcut of the destruction of Jerusalem by the Chaldeans from the Nuremberg Chronicle, 1493