Events of world-wide importance in western Europe, the extensive invasion by Christians of Mahometan Spain, and the first crusade against the Mahometans in the East, brought about important changes for the Jews of western Europe. The changes were chiefly of a deplorable kind, and interrupted their peaceful occupation with the Law. In the fortunes of Spain the Jews played no insignificant part, although their active interference is not conspicuously visible. They were helpful in digging the pit into which their great grandsons were to fall. The first powerful blow at the Islam dominion in the peninsula south of the Pyrenees was dealt by the Castilian king Alfonso VI, who was as brave in combat as he was clever in state affairs, and who placed more reliance on the sword and on diplomatic art, than on the cross and prayer. His purpose, to conquer the Mahometan kingdoms and principalities, was only attainable by fomenting dissensions among the rulers, stimulating rivalry between them, and playing off one against the other, thus weakening them all. To that end he required clever diplomatists, and among his subjects the Jews were the ones best prepared for the work. His knights were too clumsy, and his citizens too ignorant to be fitted for missions of a delicate nature. At the Mahometan courts of Toledo, Seville, Granada, there reigned a refined, cultured, intellectual tone, and frequent allusions were made in conversation to the brilliant history and literature of the Arabs. If an ambassador at these courts wanted to accomplish anything, he was obliged, not only to be acquainted with all the niceties of the Arabic language, but also to be familiar with its literature and the manners of the court. In these respects the Jews were particularly useful. Therefore Alfonso employed Jews on diplomatic missions to the courts of the Mahometan princes. One of them, the Jewish diplomatist at the court of King Alfonso, was Amram ben Isaac Ibn-Shalbib, originally Alfonso's private physician. As Ibn-Shalbib was well versed in Arabic, and possessed insight into the political circumstances of that period, the king of Castile appointed him private secretary, and entrusted him with important affairs. Alfonso had another Jewish adviser, Cidellus, who was on such intimate terms with the king, that the latter's reserve was overcome, and he permitted him to speak more freely than any of the Spanish noblemen and grandees of the empire. Alfonso, who was far from being a religious bigot, and who had acquired liberal views from his contact with the Mahometan princes, not only conferred distinctions on certain individuals among the Jews, but cleared the way to dignities and honors for all the sons of Jacob dwelling in his dominions. Alfonso had, indeed, found a certain equality in citizenship existing in many parts of Christian Spain, where custom had superseded the old Visigothic laws. According to the Visigothic code, the Jews were to be treated as outcasts, to be subjected to regulations applying to them alone, and were not to be allowed to act as witnesses. On the other hand, according to the law of custom (fueros), Christians, Jews, and Mahometans of the same town and the same country came under the same law. The Jew had to testify against the Christian on the "Torah." If Jews and Christians had a lawsuit, they had to select a Christian and a Jew as arbitrators (Alkalde). If a man wished to sell his house, two Christians and the same number of Jews had to appraise it. According to another law established by custom (fuero de Nájera), the Jews were treated on an equality with the nobles and the clergy; the same sum was fixed as compensation for the murder of a Jew, a nobleman, and a priest. Down to the smallest details of daily life, the equality between Jews and Christians before the law was made manifest. As Alfonso now confirmed these municipal laws, the civil equality of the Jews was legally acknowledged, and the ignominy of the Visigothic legislation against the Jews was effaced. Jews, under certain circumstances, were permitted to enjoy the privilege of duelling, and admitted into military service. Light seemed to be dawning upon the Middle Ages, and Roman-Christian narrow-mindedness, emanating from Theodosius II, seemed about to vanish.
However, the Church, whose foundation was intolerance, was not likely to countenance the promotion of Jews to honorable offices in a Christian land. The head of the Church, Pope Hildebrand, who, under the name of Gregory VII, through his legates and the shafts of excommunication plunged Europe into a condition of ferment and disruption, protested against this state of things. He, the mightiest of the mighty, before whom kings and nations groveled in the dust, wished also to humble the defenseless Jews, and to rob them of the respect and honors which they had acquired by their merit.
Emperor Henry IV had granted the same privileges to the Jews of Worms as to the other citizens of that town. When princes and priests, towns and villages, unmindful of their oath, and excited by the Pope, broke faith with him, and treated him as one under the ban, the town of Worms remained faithful to him. A year later, when Pope Gregory had treated the emperor as a boy, making him do penance in his shirt, he also became eager to humble the Jews. At the Church congress in Rome, in 1078, when the Pope issued for the second time his interdict against the enemies of the papacy, he promulgated a canonical law to the effect that the Jews should hold no office in Christendom, and exercise no supremacy whatever over the Christians. This canonical decision was directed principally against Spain, where, owing to the peculiar position caused by continual strife with the Arabs, the Roman Church had asserted a degree of independence. As Gregory wished to force upon King Alfonso foreign bishops, pliant tools in the execution of his will, so he endeavored to arrest the influence of the Jews at the court of Castile. He therefore addressed a vigorous epistle to Alfonso in 1080, in which the following words occur:
"As we feel impelled to congratulate you on the progress of your fame, so at the same time must we deprecate the harm you do. We admonish your Highness that you must cease to suffer the Jews to rule over the Christians and exercise authority over them. For to allow the Christians to be subordinate to the Jews, and to subject them to their judgment, is the same as oppressing God's Church and exalting Satan's synagogue. To wish to please Christ's enemies means to treat Christ himself with contumely."
On the other hand, the Pope was well satisfied with William the Conqueror, King of England and Duke of Normandy, who ratified the decision of the congress in Rouen, that the Jews were not only prohibited from keeping Christian bondmen, but also from having Christian nurses.
But Alfonso had to give his attention to other affairs besides the intolerance of the Church. He troubled himself but little about the decision of the great council in Rome and the autograph letter of the Pope, and retained his Jewish advisers. He was just then revolving in his mind a plan of invading the kingdom of Toledo. In order to accomplish this he had to isolate its governor from the neighboring princes of his faith and race, and to be assured of their neutrality or their co-operation with himself. For that, however, he required his Jewish diplomatists, and could not entertain the idea of satisfying the importunities of the Pope. By an alliance with the noble and valiant king of Seville, Al-Mutamed Ibn-Abbad, in all probability effected by Jewish agents, Alfonso conquered the old and important town of Toledo (1085), the first bulwark of the Spanish Mahometans against the aggressive power of the Christians. The victor of Toledo assured to the Jews of this town and the territory appertaining to it, all the liberties which they had enjoyed under the Mahometan rulers. The last unfortunate Mahometan king of Toledo, Yachya Alkader, who had to take refuge in Valencia, had a Jewish confidant in his suite, who remained faithful to him long after his death, whilst his nearest friends betrayed him.
Alfonso did not rest satisfied with the possession of Toledo, which was again elevated to the rank of capital, but wished to make use of the disagreements and petty jealousies of the Mahometan princes for the purpose of making fresh conquests. First of all he determined to attack the territory of the king of Seville, who also ruled over Cordova. He therefore suddenly dropped the mask of friendship, and made demands of Al-Mutamed, such as this noble prince could not in honor concede. With the perilous mission of revealing the true state of affairs to the king of Seville, and of facing him in a firm and defiant attitude, Alfonso entrusted his Jewish councillor of state, Isaac Ibn-Shalbib, instructing him not to pay any regard to the requirements of courtesy. Five hundred Christian knights accompanied Alfonso's Jewish messenger to the court of Seville, in order to lend dignity to his embassy. This commission cost Ibn-Shalbib his life. Acting in the spirit of his master, he spoke in terms so positive, and insisted so unflinchingly on the fulfilment of the demand he was charged to make, that Al-Mutamed fell into a violent passion, and transgressed the law protecting the person of an ambassador, had Ibn-Shalbib killed, nailed to a gibbet, and his followers imprisoned.
The breach which in consequence occurred between Alfonso and the king of Seville induced the latter to join the league of the rest of the Mahometan princes, and send for the conqueror of northern Africa, the Almoravide Prince Yussuf Ibn-Teshufin, to aid them against Alfonso. Al-Mutamed spoke the deciding word in favor of this plan. The African hero appeared in response to the invitation, and his presence eventually caused the servitude and downfall of the Andalusian princes.