The 11th-century Investiture Controversy was a struggle between the Holy Roman emperors and the papacy over who held the right to appoint bishops within imperial territories. Bishops were major landowners and political administrators; whoever appointed them controlled a part of medieval European governance.
Pope Gregory VII (Hildebrand of Sovana) had become pope in 1073 and was a reformer determined to recover ecclesiastical appointments from secular rulers. Emperor Henry IV had inherited the long imperial practice of personally investing bishops with their offices. By 1075 the two men were in open conflict.
In January 1076 Henry called a synod at Worms that declared Gregory deposed. Gregory responded in February 1076 by excommunicating Henry and releasing the German nobles from their oaths of fealty.
Why excommunication mattered
The excommunication threatened Henry’s empire. Several German territorial princes had been waiting for political cover to break their loyalty oaths. By autumn 1076 a coalition of rebel German princes was meeting at Tribur, near Mainz, and announced that they would elect a new king if Henry did not have the excommunication lifted by February 1077.
Henry had four months. He left Speyer at Christmas 1076 with his wife and infant son and crossed the Alps in mid-winter — through the Mont Cenis pass at the worst time of year. The crossing involved local guides leading the imperial party down the icebound passes on ox-hides; the empress was reportedly carried down the steepest sections on a sledge.
Gregory was at the time in northern Italy at the fortress of Canossa — the seat of Henry’s principal Italian opponent, the Tuscan margravine Matilda of Tuscany. Henry presented himself at Canossa on 25 January 1077.
Three days
Gregory refused to admit him. The chronicler Lampert of Hersfeld records — with dramatic detail that has been disputed in particulars but not in essence — that Henry stood outside the outer gate of the fortress for three days. He wore a hairshirt, was barefoot, took no food, and stood in deep January Apennine snow.
The performance was a public theological gesture. Imperial penance, in medieval Catholic doctrine, was the prescribed ritual for restoring a Christian sinner to communion. Henry was performing the most public possible version of the ritual. To refuse him admission indefinitely would have made Gregory look uncharitable in front of a audience including Matilda of Tuscany, the Abbot Hugh of Cluny, and the political reporting class of northern Italy.
On the morning of 28 January 1077 Gregory admitted Henry. The excommunication was lifted. Henry kissed the pope’s foot and was readmitted to communion.
What happened next
The German rebel princes elected an anti-king (Rudolf of Swabia) anyway in March 1077. The civil war that followed ran for nine years. Henry deposed Gregory at a 1080 council and installed an antipope. Gregory died in exile at Salerno in 1085. Henry continued to rule until his own forced abdication in 1105.
The Investiture Controversy was resolved by the Concordat of Worms in 1122 under Henry IV’s son Henry V — a compromise that gave the papacy ecclesiastical investiture and the emperor temporal investiture.
The phrase “to go to Canossa” entered the German political vocabulary as the canonical expression for political humiliation through ostentatious penance. Otto von Bismarck reportedly said during the 1872 Kulturkampf conflict with the Catholic Church: “Nach Canossa gehen wir nicht” — “we shall not go to Canossa.”