Today is the 20th of Sivan, a date which for close to three hundred years was commemorated as a fast day with selichos throughout most of Eastern Europe. The fast was first instituted by the Shach for his immediate family in response to the massacres of Tach v’Tat (1648-49) that directly affected his community and family. The Taz, who also lost family members to the pogroms, as well as the Tosfos Yom Tov, expanded on the Shach’s personal fast, which was ultimately adopted by the Four Lands (Arba Aratzos, which covered Poland, Ukraine, as well as other areas). This date, as well as the special Selichos that were composed specifically for this fast, was observed until recent times. The Mishnah Berurah, in Hilchos Taanis, makes reference to the fast of the 20th of Sivan.
The fact that post-Holocaust Jews no longer observe the 20th of Sivan as a fast day is, in my opinion, a direct result of Churban Europa, which was an attempt to destroy the richness of European Jewish life and customs, as well as annihilate a people. This is especially sad as the Shach and others specifically selected the 20th of Sivan for the fast as it could never fall on Shabbos and would, therefore, remain a permanent fast day for future generations.
Although most of us no longer fast today, let us say tehillim and daven on this special day of rachamim for the safe return of our three Yeshiva students in Israel.
Yizkereim/Rabbi Leib Geliebter Memorial Foundation