The circumstances were in the main in the pope's favour. Henry was rebelled against in Germany, and Gregory was well able to manipulate disaffection. At the same time, Gregory's strenuous efforts to "reform" the Church by forcing celibacy on the entire priesthood had set against him multitudes of the Italian and northern clergy, married and unmarried; and these were indignant at Henry's surrender. Stimulated by their protests, and by the sympathy of various kings whom the pope had arrogantly menaced, he took heart, put down his rebels and rivals at home, and marched in force into Italy, where he met almost no resistance and was crowned by the antipope Clement III, whom he and his party had appointed. Gregory, besieged by his own flock in the castle of St. Angelo, called in his late-made ally the Norman Robert Guiscard, Duke of Sicily, who in releasing him burnt much of the city, and, after a sack and massacre, sold most of the remaining inhabitants as slaves. Everywhere the pope's cause was lost, and he died defeated, in exile at Salerno under Norman protection, hated by both priests and people as the bringer of slaughter and misery on Germany and Italy alike. The "reforming" pontiff had wrought far more evil than his most sinful predecessors, and still the Church was not reformed. Henry, rebelled against by his sons, died broken-hearted like his enemy; and for half a century the strife over "lay investitures" was carried on by popes and emperors. The papacy had thus become the evil genius at once of Italy and of Germany, entering into and intensifying every Italian feud, and giving to German feudalism a fatal ground of combat for centuries. Out of all the strife the papacy made ultimate profit. When the war of the investitures was over, it built up the Decretum of the monk Gratian, a code embodying the Isidorean frauds with others, such as the gross pretence that St. Augustine had declared the Decretals to be of the same status with the canonical scriptures. The war, meantime, had ended in a compromise from which also the papacy substantially gained. The result was to turn it ere long into a vast system of financial exploitation. Every evil in the way of simony and corruption against which Hildebrand had revolted was further developed under papal auspices. The people lost all power of electing their bishops; and the rich chapters, on whom the right devolved, became the field of simony for the nobles; while the pope drew from the sale of his ratifications an immense revenue. So rapid was the effect of the new relation that by the middle of the twelfth century the bulk of the current literature of Europe, serious and satirical, was bitterly hostile to Rome, which now impressed many instructed men chiefly as a great machine for extortion. While the Church officially denounced usury, its own usurers were everywhere drawing interest from prelates who had had to borrow money to buy their investitures.