But Gregory’s successor, Urban, as resolute and more subtle, retrieved what had only been a check.  The Crusades, essentially of ecclesiastical inspiration, were given their great impulse by him; they were a movement of Christendom against the Paynim, of the Church against Islam; they centred in the pope, not the emperor, and they made the pope, not the emperor, conspicuously the head of Christendom.

The twelfth century was the age of the Crusades, of Anselm and Abelard, of Bernard of Clairvaux, and Arnold of Brescia.  It saw the settlement of the question of investitures, and in England the struggle between Henry II. and Becket, in which the murder of the archbishop gave him the victory.  It saw a new enthusiasm of monasticism, not originated by, but centring in, the person of Bernard, a more conspicuous and a more authoritative figure than any pope of the time.  To him was due the suppression of the intellectual movement from within against the authority of the Church, connected with Abelard’s name.

Arnold of Brescia’s movement was orthodox, but, would have transformed the Church from a monarchial into a republican organisation, and demanded that the clergy should devote themselves to apostolical and pastoral functions with corresponding habits of life.  He was a forerunner of the school of reformers which culminated in Zwingli.

In the middle of the century the one English pope, Hadrian IV., was a courageous and capable occupant of the papal throne, and upheld its dignity against Frederick Barbarossa; though he could not maintain the claim that the empire was held as a fief of the papacy.  But the strife between the spiritual and temporal powers issued on his death in a double election, and an imperial anti-pope divided the allegiance of Christendom with Alexander III.  It was not till after Frederick had been well beaten by the Lombard League at Legnano that emperor and pope were reconciled, and the reconciliation was the pope’s victory.

III.—­Triumph and Decline of the Papacy

Innocent III., mightiest of all popes, was elected in 1198.  He made the papacy what it remained for a hundred years, the greatest power in Christendom.  The future Emperor Frederick II. was a child entrusted to Innocent’s guardianship.  The pope began by making himself virtually sovereign of Italy and Sicily, overthrowing the German baronage therein.  A contest for the imperial throne enabled the pope to assume the right of arbitration.  Germany repudiated his right.  Innocent was saved from the menace of defeat by the assassination of the opposition emperor.  But the successful Otho proved at once a danger.