The famous French monk Gerbert being elected pope in 999, under the name of Sylvester II., addressed a letter to all Christians, in which he supposes the Church of Jerusalem speaking from its ruins, and calling upon them to take up arms and fight boldly to deliver it from oppression. Gregory VII. also undertook, in 1074, to form a crusade against the Turks, in favour of Michael, emperor of the East; but as he died before he could put his plan into execution, his successor, Urban II., caused it to be proclaimed in the Council of Clermont, in the year 1095. The efforts of the pope had an incredible success; a numerous army left Europe soon after, which first took the city of Antioch, and afterwards Jerusalem in 1099. The injustice of this war, and the other expeditions of the same kind which succeeded it, would have disgusted all Europe, if the people had not been prepossessed with the absurd idea, that it was meritorious to make war for the exaltation and glory of Christianity: the consequences of a system so fatal to temporal power were felt in France at the time of the Patarians, Catharians, and other sects of Manès. Alexander III., having sent Peter, Bishop of Meaux, to Count Raymond V. of Toulouse, that legate made him and all his nobles take an oath that they would not favour the heretics who had taken up arms in defence of their party; and in the Council of Lateran, the following year, the fathers declared that though the church did not approve of sanguinary measures, yet she would not refuse the assistance offered by Christian princes: in consequence, Alexander not only excommunicated the heretics and their adherents, but promised all those who should die in the war against them absolution and salvation, and for the present granted indulgences for two years to all who should take up arms. In 1181, Cardinal Henry, Bishop of Alva, was sent into France to pursue the war against the Albigenses; but this expedition did not entirely destroy that party, and a new council was held, in whose decrees Cardinal Fleury supposes he has discovered the origin of the Inquisition. He was not mistaken in this opinion, but it was not at that time actually instituted, since the bishops alone, as they had always been, were commissioned to preserve the faith. The council recommended that the bishops, or their archdeacons, should visit the dioceses once or twice a year, and that they should cause the inhabitants to take an oath that they would denounce all heretics, or persons who held meetings, to the bishop or archdeacon. The council also decreed that counts, barons, and other nobles should take an oath to discover heretics and punish them, on pain of excommunication and deprivation of their estates and employments.