Second Excommunication of Henry
That the excommunication of Henry IV was simply a pretext for the opposition of the rebellious German nobles is transparent. Not only did they persist in their policy after his absolution, but they took the more decided step of setting up a rival ruler in the person of Duke Rudolf of Swabia at Forchheim in March 1077. At the election, the papal legates present observed the appearance of neutrality, and Gregory himself sought to maintain this attitude during the following years. His task was made easier in that the two parties were of fairly equal strength, each trying to gain the upper hand by getting the pope on their side. But the result of his non-committal policy was that he largely lost the confidence of both parties. Finally he decided for Rudolf of Swabia after his victory at the Battle of Flarchheim on 27 January 1080. Under pressure from the Saxons, and misinformed as to the significance of this battle, Gregory abandoned his waiting policy and again pronounced the excommunication and deposition of King Henry on 7 March 1080.
But the papal censure now proved a very different thing from the one four years before. It was widely felt to be an injustice, and people began to ask whether an excommunication pronounced on frivolous grounds was entitled to respect. To make matters worse, Rudolf of Swabia died on 16 October of the same year. A new claimant, Hermann of Luxembourg, was put forward in August 1081, but his personality was not suitable for a leader of the Gregorian party in Germany, and the power of Henry IV was at its peak. The king, now more experienced, took up the struggle with great vigour. He refused to acknowledge the ban on the ground of its illegality. A council had been summoned at Brixen, and on 16 June it pronounced Gregory deposed and nominated the archbishop Guibert of Ravenna as his successor. In 1081 Henry opened the conflict against Gregory in Italy. The latter had now become less powerful, and thirteen cardinals deserted him.
The pope's chief military supporter, Matilda of Tuscany, blocked Henry's armies from the western passages over the Apennines, so he had to approach Rome from Ravenna. Rome surrendered to the German king in 1084, and Gregory thereupon retired into the exile of the Castel Sant'Angelo and refused to entertain Henry's overtures, although the latter promised to hand over Guibert as a prisoner, if the sovereign pontiff would only consent to crown him emperor. Gregory, however, insisted as a necessary preliminary that Henry should appear before a council and do penance. The emperor, while pretending to submit to these terms, tried hard to prevent the meeting of the bishops. A small number assembled nonetheless, and, in accordance with their wishes, Gregory again excommunicated Henry.
Henry, upon receipt of this news, again entered Rome on 21 March to see that Guibert of Ravenna be enthroned as Clement III as of 24 March 1084. Henry was crowned emperor by his creature, but Robert Guiscard, with whom in the meantime Gregory had formed an alliance, was already marching on the city, and Henry fled towards Civita Castellana.
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