Jewish communities had long been established in Europe, where local rulers and bishops often encouraged Jewish settlement for sound economic reasons: Jews were commonly traders and bankers, at a time when Christians were not mean to lend money and levy an interest rate for so doing (the sin of usury). In particular, Jews had settled in France and Germany in the 10th century. Anti-Semitism came in their wake: long lived beliefs in Jews as ‘Christ-killers’, and a source of moveable wealth. Throughout medieval history, that anti-Semitism could lead to violence, pogroms (campaigns of violent persecution) and systematic attempts to convert Jews to Christanity, often by force.
The surge of crusading passion brought anti-Semitic passions, and pogroms, in its wake. As the pilgrims gathered behind Little Peter, their leader was not averse to anti-Semitic preaching. His forces may not have resorted to violence, he seems to have been attempting to extort money from Cologne’s wealthy Jews to subsidise his campaigns; his followers were less restrained: when they reached Regensburg, they quickly resorted to the forced conversion of the local Jews. Even more serious was the pogrom that accompanied the mustering of crusaders led by Emich of Flonheim in south and west Germany in 1096. The pogrom of 1096 was begun in Speyer, where Emich’s men had assistance from some of the townsfolk, but were opposed by others (including the local bishop). At Worms, hundreds were killed, many others forcibly converted. At Mainz, a two day orgy of desecration, murder and forcible conversion ensued. By the time he reached Cologne, many of its Jews were in hiding, Even after Emich’s forces had been denied passage through Hungary and his army had fallen apart after being defeated by Hungarian forces, anti-Semitic violence continued.
Such violence was not an accident. It was not sanctioned by the church. The church was virulently anti-Semitic, but it did not approve of pogroms. In part, the church taught that the ultimate conversion of the Jews would come, signally the second coming; as a substantial secular power, it wanted the Jewish presence for the same reason local elites often did. Local secular elites, and many ordinary Christians, sought to protect Jews: indeed, the creation of Jewish ghettos, with walls, was often as much to protect Jews as it was the separate them. Instead, the violence came from people fired with a mix of avarice and crusading zeal. In Mainz, there was much talk of avenging the blood of Christ.
The process of evangelizing the Second Crusade saw a similar outbreak of anti-Semitic violence. Bernard of Clairvaux had sought to control the process of preaching, but as before some preached the crusade without license, others went way beyond the official line. A Cistercian monk, Radulf, another charismatic holy man like Bernard himself, despite the opposition of the archbishops of Cologne and Mainz, and of Bernard himself, launched a populist preaching campaign which featured a maniacal anti-Semitism: ‘Avenge the crucified one upon his enemies who stand before you; then go to war with the Muslims’. Otto of Friesing called for Jews to be killed as ‘foes of the Christian religion’.
Nor were they alone. Indeed, whilst Bernard may of opposed Radulf was merely arguing for legal tolerance because the Jews were the ‘living words of scripture, for they remind us always of what our Lord suffered’. Other churchmen, such as the abbot of Cluny, Peter the Venerable, whilst arguing that Jews should not be killed, called them ‘detestable’ and called for them to be punished as ‘enemies of Christ’. The violence of 1146-47 often had a ritualistic element: at Ramerupt the crusaders inflicted five wounds on Rabbi Jacob’s head, openly referring to the five wounds of Christ as they did.
Popular attacks on Jews had already begun as the crusade was preached before Radulf got going. Once he had though, things got worse: the Jewish chronicler Rabbi Ephrahim of Bonn records three massacres. In contrast to the pogrom of 1096, the pogroms of 1146-47 were more sporadic, mostly thanks to the protection offered Jews by local rulers. Nonetheless, there were murders, forced conversions, desecrations and the rest, and rumours of many more. In part, Bernard of Clairvaux’s famous preaching tour of Germany in 1147 was designed to counter that of Radulf; he eventually caught with him at Mainz and forced Radulf to desist. Bernard thus stopped the preaching of a pogrom and, perhaps most of all, asserted his authority over a rival.
In 1190, Richard I’s coronation in 1189 was accompanied popular anti-Jewish riots against the ‘enemies of the Cross of Christ’. The recruiting process the following year for the Third Crusade was accompanied by anti-Jewish violence in places such as King’s Lynn and Stamford, reaching a grizzly climax when local notables led an attack by crusaders in York, leading to the infamous massacre and mass suicide of the city’s Jews at Clifford’s Tower. In contrast, a few days later in Lincoln, royal officials successfully protected Jews.

It might be argued that where crusading zeal led to open anti-Semitic violence, that violence was permitted because of a lack of a strong central authority. In a Germany effectively ruled by the formidable Frederick Barbarossa, the Jews took refuge and were protected by the authorities. In an England without a present king (and Richard was long gone from England by 1190) saw authorities either unable or unwilling to resist crusading zeal and the anti-Semitic pogroms it all too often unleashed.