On Tisha B’Av, mourning incomparable loss, working on increased unity feature On Tisha B’Av, mourning incomparable loss, working on increased unity The holiday marked by Jewish calamities associated with internecine strife is an annual reminder to move past the divisiveness of politics, enmity and isolation. (July 14, 2021 / JNS) Why is Tisha B’Av the saddest day of the Jewish year? Eerily, not only were both of the holy temples in Jerusalem destroyed on the ninth day of the Hebrew month of Av (the first one, built by King Solomon, was demolished by the Babylonians in 586 BCE, and the second, a gift of King Herod, by the Romans in 70 C.E.), but a host of other tragic events also befell the Jewish people on that date.