Q. Why do the Tishah B’Av prayers only deal with ancient tragedies? What about the Holocaust?
A. Your question is based on faulty information. The kinnot for Tishah B’Av focus on a whole tragic sequence of calamities, which almost always tended to cluster around the ominous date of 9 Av.
Why so much happened on this date is suggested by the Talmud. The Torah says, “And the congregation lifted their voice and cried, and the people wept that night” (Num. 14:1). The sages believed that “that night” was Tishah B’Av, and God said, “Because you wept without cause, I will fix this night for you for eternal weeping” (Ta’anit 29a).
This does not necessarily mean that the people brought the tragedies upon themselves, but that when tragedy occurred, so often it coincided with Tishah B’Av.
The kinnot memorialise so many destructions over the centuries that it is quite impossible to conclude that only ancient events are described.
Recent decades have seen yet more Tishah B’Av tragedies, including the outbreak of World War I and in 1940 the erection of ghettoes in Poland. So there are specific Holocaust events that occurred at this time of the year that clearly warrant appropriate commemorations.
The Tishah B’Av liturgy has in fact been augmented by Holocaust kinnot, and countless people have chosen this date as the national Yahrzeit on which to say the older and newer kinnot and to mourn for all that has been lost.