Rhineland massacres

The call for the First Crusade touched off the Rhineland massacres also known as the German Crusade of 1096, the persecutions of 1096 or Gzerot Tatenu (Hebrew: גזרות תתנ"ו‎‎) for the edicts of 856, which occurred during the year of 4856 according to the Jewish calendar. Prominent leaders of crusaders involved in the massacres included Peter the Hermit and especially Count Emicho. As part of this persecution, the destruction of Jewish communities in Speyer, Worms and Mainz were noted as the "Hurban Shum" (Destruction of Shum). These were new persecutions of the Jews in which peasant crusaders from France and Germany attacked Jewish communities. A number of historians refer to the antisemitic events as "pogroms".

According to David Nirenberg, the events of 1096 in the Rhineland "occupy a significant place in modern Jewish historiography and are often presented as the first instance of an antisemitism that would henceforth never be forgotten and whose climax was the Holocaust."

The preaching of the First Crusade inspired an outbreak of anti-Jewish violence. In parts of France and Germany, Jews were perceived as just as much an enemy as Muslims: they were held responsible for the crucifixion, and they were more immediately visible than the distant Muslims. Many people wondered why they should travel thousands of miles to fight non-believers when there were already non-believers closer to home.

It is also likely that the crusaders were motivated by their need for money. The Rhineland communities were relatively wealthy, both due to their isolation, and because they were not restricted as Catholics were against moneylending. Many crusaders had to go into debt in order to purchase weaponry and equipment for the expedition; as Western Catholicism strictly forbade usury, many crusaders inevitably found themselves indebted to Jewish moneylenders. Having armed themselves by assuming the debt, the crusaders rationalized the killing of Jews as an extension of their Catholic mission.

...
Wikipedia