HT: Daniel
The Magen Avraham writes: [Orach Chaim 580:9] it is the custom of pious individuals to fast on the Erev Shabbos preceding Parshas Chukas in observance of a tragic event which occurred on that day. On 9 Tammuz 5004, 24 cartloads of the Gemora and other holy books were publicly burned in France due to allegations of heretical and rebellious teachings contained therein.
Rav Hillel of Verona, a student of Rabbeinu Yonah, writes that his illustrious teacher noted that just 40 days prior to this episode, the Jews had publicly burned in that very spot a number of copies of the controversial philosophical writings of the Rambam. Rabbeinu Yonah saw in this tragedy Divine punishment being meted out for their actions, and he viewed it as a Heavenly message supporting the legitimacy of the teachings of the Rambam. The Jews of the time repented their actions and prayed for Divine forgiveness, thus ending the bitter controversy over the philosophical views of the Rambam.
Although fasts commemorating historical events are normally established on the calendar date on which they occurred – in this case 9 Tammuz – the Rabbis of the time mystically inquired regarding the nature of the decree, and received the cryptic reply “da gezeiras Oraisah” – this is the decree of the Torah. This expression is taken from Onkelos’ Aramaic translation of the second verse in Parshas Chukas. They interpreted this message as alluding that the decree was connected to the day’s proximity to the reading of Parshas Chukas, so they established the fast specifically on the Erev Shabbos preceding the reading of Parshas Chukas. Source: Shema Yisrael
Rav Hillel of Verona, a student of Rabbeinu Yonah, writes that his illustrious teacher noted that just 40 days prior to this episode, the Jews had publicly burned in that very spot a number of copies of the controversial philosophical writings of the Rambam. Rabbeinu Yonah saw in this tragedy Divine punishment being meted out for their actions, and he viewed it as a Heavenly message supporting the legitimacy of the teachings of the Rambam. The Jews of the time repented their actions and prayed for Divine forgiveness, thus ending the bitter controversy over the philosophical views of the Rambam.
Although fasts commemorating historical events are normally established on the calendar date on which they occurred – in this case 9 Tammuz – the Rabbis of the time mystically inquired regarding the nature of the decree, and received the cryptic reply “da gezeiras Oraisah” – this is the decree of the Torah. This expression is taken from Onkelos’ Aramaic translation of the second verse in Parshas Chukas. They interpreted this message as alluding that the decree was connected to the day’s proximity to the reading of Parshas Chukas, so they established the fast specifically on the Erev Shabbos preceding the reading of Parshas Chukas. Source: Shema Yisrael
Erev Shabbos preceding Parshas Chukas 5776 - 10.30pm local time - 9 Tammuz - 84 people were killed when a truck careened through crowds of people celebrating Bastille Day in the southern French city of Nice.
So not only was it the same date - 9 Tammuz - it was also Erev Shabbat - the exact time that the fast day was decreed to be held.