Today, 849 years ago, in the year 1171, the holy Jewish community of Blois (French pronunciation: Blwa) was slaughtered and burned.
This was the very first blood libel in Jewish history in Europe. The whole community was sentenced to death. At first, they were enclosed in a wooden stable which was put on fire. The Jews started to sing Aleinu Leshabeach, and wonder of wonders, they survived the fire. The gentiles then slaughtered them all and burned their bodies.
Rabeinu Tam has set this day as a Taanis Tzibbur