From the notes of Dr. David Neiman:

The First Crusade, launched in 1096, initiated a series of violent acts against the Jews of Europe, in the course of which, entire Jewish communities were annihilated. Mainz, Worms, and Speyer were three Rhineland cities whose communities were savaged and devastated by the crusaders in preparation for their departure for the Holy Land. The subsequent wars of the Cross inflicted further pain and suffering on the Jewish populations of Europe.

The middle of the 13th century saw the escalation of powerful religious fanaticism in the Christian world which led to oppression of the Jewish communities on a large scale. These uprisings, which might have been stimulated by social and economic factors, were taken over and led by members of religious orders, primarily Franciscans and Dominicans, the Order of Preachers. These militant warriors, defenders of the Christian faith, launched attacks on Jewish communities, in many cases leading to destruction and annihilation of some and expulsions on a large scale. In some cities the Jews were challenged to participate in public debates, referred to as "Disputations." The enthusiasm for anti-Jewish agitation was exacerbated, fueled by rumors, widely circulated, that all of Jewish learning was directed against the Church. It was also bruited about that Jewish literature, especially the Talmud, was filled with anti-Christian propaganda, including insults to the members of the Holy Family. Since all of Jewish literature and especially rabbinic writings are in Hebrew or in Jewish-Aramaic, languages of which most Christians were ignorant, and since renegade Jewish apostates were the ones who spread these rumors, the falsehoods were taken to be truth.

About Dr. Neiman:

Dr. David Neiman (1921-2004) was the first Jewish scholar appointed to teach Religion at Boston College, one of America's leading Catholic Universities. He served as Professor in the Department of Theology for a quarter of a century. While there he was also invited to teach at the Pontifical Gregorian University in Rome. After retiring from Boston College, Dr.Neiman moved to Los Angeles, where he taught at Loyola Marymount University, St. John' s Seminary in Camarillo and the University of Judaism in Bel Air.