Henry's first task after assuming control was to restore his authority in the duchies, especially in Saxony, where a revolt (1073) was subdued in 1075. He then turned his attention to Italy, where he sought to restore imperial authority; this provoked a conflict with the papacy. Henry disregarded the opposition of Pope Gregory VII to lay investiture and invested a new bishop of Milan. Gregory supported the previous bishop, who had been put in office by a revolutionary movement in the city, and threatened Henry with deposition. Henry summoned a council at Worms, which declared Gregory deposed (Jan., 1076).
Gregory, at a synod in Feb., 1076, declared Henry excommunicated and deposed and absolved his subjects of their oaths of fealty. A powerful coalition of German nobles, including the rebellious Saxons, agreed (Oct., 1076) not to recognize the king unless he obtained absolution by February; his fitness to rule was to be decided at a diet to be held at Augsburg under the chairmanship of the pope. To forestall the action of this diet, Henry crossed the Alps in the dead of winter to seek absolution. By his humiliation and penitence he moved the pope to grant him absolution at Canossa in Jan., 1077.
Despite the absolution, the rebel dukes were determined to depose Henry, and they elected Duke Rudolf of Swabia antiking, thus plunging Germany into civil war. Gregory remained neutral until Mar., 1080, when he renewed Henry's excommunication and deposition and recognized Rudolf's title. But Henry was now supported by a large party; German and Italian bishops joined him in declaring Gregory deposed and in electing an antipope, Clement III (see Guibert of Ravenna).
Rudolf died in 1080, and his supporters elected a Lotharingian count, Herman of Salm, to succeed him. By this time, however, the German revolt was practically broken, and in 1081 Henry carried the war into Italy. After several unsuccessful attempts he occupied Rome in 1084, installed Clement III as pope, and was crowned emperor. He retired before the advance of Gregory's Norman allies under Robert Guiscard, who rescued Gregory but plundered Rome. The Normans then withdrew from Rome, taking Gregory, who had gained the hatred of the Romans, with them.
In Germany, Henry broke (1088) the power of Herman, but his stubborn support of Clement III against Gregory's successors made his own family turn against him because they felt he was endangering the monarchy. When his son Henry (later Henry V) rebelled in 1104, only the Rhenish cities were loyal to the emperor. Trapped by a promise of conciliation, Henry IV was imprisoned and forced to abdicate (1105). In 1106, just before his death, he escaped and received considerable support. During his reign Henry was caught between the rising particularism of the princes and the reformist demands of a revivified papacy, but he managed to salvage enough of his father's legacy to make possible a restoration of imperial power under the Hohenstaufens.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.