I have heard many times that Tisha B’av is historically related to the tragedy of the Holocaust (in print see Rav Soloveitchik, 2006, p. 226, and Press, 1996, p.70). The claim is that World War I started on Tisha B’av in 1914, and World War II is a continuation of WWI. Almost certainly future generations will view the two world wars, which were so close in years and involved almost the exact same countries fighting each other, as one war, yet this connection is not just ex post. During the negotiations leading up to the Treaty of Versailles, which officially concluded WWI, John Maynard Keynes (1919), wrote a celebrated essay “The Economic Consequences of the Peace” where he predicted that the harsh terms of the treaty imposed on Germany in the Treaty of Versailles would lead to another war.
Accordingly, it is reasonable to see a connection between WWI and the Holocaust, but did WWI begin on Tisha B’av? This cannot be answered definitely since is not clear on which day the war began. Tisha B’av in 1914 was on August 1, which was the day when Germany declared war on Russia. Yet, one could argue for other dates for the beginning of WWI such as June 28 1914 when the Archduke Francis Ferdinand was assassinated, July 28th when Austria-Hungary declared war on Serbia, July 30th when Russia ordered a general mobilization or August 3 when Germany declared war on France and invaded Belgium. Thus, it seems that while WWI started around the time of Tisha B’av, one cannot categorically state that it started on Tisha B’av. However, even if there is no exact historical connection, as Tisha B’av is a day of national mourning it still is appropriate to remember the Holocaust on Tisha B’av.
One of the themes of Tisha B’av is that while we have suffered on this day, the day will eventually be a festival since it will be related to the future redemption. If the present state of Israel is the beginning of the redemption (and we should remember the failure of Bar Kokhba) and one has accepted the argument above that WWI is connected with Tisha B’av, then maybe one can claim that the same Tisha B’av of 1914 relates to the future redemption. I have heard it argued that the “world” allowed Israel to exist because of its guilt for the Holocaust. I have never liked this argument, as for example Great Britain showed no evidence of any guilt about the Holocaust when it acted with tremendous cruelty in not allowing Jews to come to Israel after WWII. Yet, one could make the simpler argument that WWI itself led to the founding of the state of Israel.
In 1917, near the end of WWI, after Great Britain had captured the southern part of the land of Israel, it announced the Balfour Declaration, which committed Great Britain to support "the establishment of a national home for the Jewish people" in the land of Israel. In 1918, Great Britain conquered the remainder of the land of Israel from Turkey and ruled the land, as a British mandate, until May 1948. Initially Great Britain was very supportive of Jews coming to Israel, and throughout the entire period it helped foster the development of the economy in the land. Under the British mandate the Jewish population in Israel rose from around 56,000 people in 1918 to 650,000 in 1948. It is hard to imagine that such a growth in population would have occurred had the land of Israel remained under Turkish rule. Furthermore, throughout almost the entire Mandate period, including the years of the Great Depression and WWII, the economy boomed in the land of Israel, as the area had the second highest growth rate in the world from 1922-1947, and this economic growth was one of the factors (the main one?) that enabled the Jewish population to achieve independence in 1948. (For more information on the excellent economic growth in the land of Israel under the British, see Schein 2007, 2012 and 2016.)