In the first teshuva in his collection, Rabbi Oshry describes a case where the Nazis brought many cats and dogs into the Beit Midrash in the Kovno ghetto and slaughtered them. Not content with that desecration of a holy site, they then had Jews come forward and tear the sifrei Torah to be used to cover the rotting corpses of the slain animals.
The question that emerged was whether a general fast day or some other public expression of mourning could be proclaimed as a result of this incident.
Rabbi Oshry first deals with the halacha as it pertains to those who actually witnessed the incident. After dealing with a potential variant text in the Gemara in Moed Katan 26a, he concludes that anyone who actually saw the sifrei Torah being torn had to tear keriah. With regard to others in the ghetto who did not witness the incident, and who perhaps did not even see what had happened, Rabbi Oshry deliberates, weighing the issue that such a horrific incident is clearly a call from Hashem to repent against the fact that there does not seem to be a strong source obligating the masses to take any definitive action.
In the end, Rabbi Oshry concluded that there was certainly no need for people to fast as a result of this incident, particularly in light of their generally weakened state due to the lack of proper nutrition in the ghetto. However, anyone who wanted to give tzedaka as a result of this event was encouraged to do so, and Rabbi Oshry used the following Shabbat as an opportunity to arouse the people to do teshuva and to be particularly careful in the respect that they accorded sifrei Torah.