The moment
Answering an appeal for help from the Byzantine emperor Alexios I, Pope Urban II called on Latin Christians at Clermont in November 1095 to march east and take Jerusalem. On the way, in May 1096, crusader bands, among them one led by Count Emicho, attacked the Jewish communities of Speyer, Worms, Mainz and Cologne and killed well over a thousand people. When the crusaders stormed Jerusalem in July 1099 they massacred many of its Muslim and Jewish inhabitants, and the states they set up lasted nearly two centuries.