As western Christianity was subsumed by the Dark Ages, the medieval era of European history, the traditional bonds of secular rule disintegrated to the local feudal lord. At the same time the bonds between Rome, diocese, and local parishes and abbeys also fell apart. When came the time to appoint a new church leader, the conditions were ripe for an investiture controversy of epic proportions. Theology was not a leading issue….yet. The major actors were wealth and land.Since a substantial amount of wealth and land was usually associated with the office of a bishop or abbot, the sale of these Church offices (a practice known as simony) was an important source of income for the church. For leaders among the nobility, who themselves owned the land and by charity allowed the building of churches, it was about consolidating power and control. Since bishops and abbots were themselves usually part of the ruling nobility, due to their literate administrative resources or due to a familial relationship, younger sons of the nobility would often be appointed bishops, as their older siblings inherited the titles. It was beneficial for a ruler or nobleman to appoint (or in turn sell the office to) someone who would be loyal, as priests who were outside the ruling nobility did not inherit, nor earn substantial wealth, may be swayed by greed and power – or more specifically greed and power not in the family interest.

The crisis began when a group within the church, members of the Gregorian Reform, decided to rebel against the practice of simony by forcefully taking the power of investiture from the ruling secular power, i.e. the Holy Roman Emperor and placing that power wholly within control of the Church. The Gregorian reformers knew this would not be possible so long as the emperor maintained the de-facto ability to appoint the pope, so their first step was to forcibly gain the papacy from the control of the emperor. An opportunity came in 1056 when Henry IV became German king and Holy Roman Emperor (HRE) at six years of age. The Gregorian reformers seized the opportunity to take the papacy by moral force while he was still a child and could not react. In 1059 a church council in Rome declared, with In Nomine Domini, that leaders of the nobility would have no part in the selection of popes and created the College of Cardinals as a body of electors made up entirely of church officials. Once Rome regained control of the election of the pope it was ready to attack the practice of investiture and simony on a broad front.

By 1075, Henry IV was no longer a child, and he continued to appoint his own bishops. When the pope reasserted that such power resided only in the Holy See, Henry sent Gregory VII a letter in which he withdrew his imperial support of Gregory as pope in no uncertain terms: the letter was headed “Henry, king not through usurpation but through the holy ordination of God, to Hildebrand, at present not pope but false monk.” The letter called for the election of a new pope. The letter ends, “I, Henry, king by the grace of God, with all of my Bishops, say to you, come down, come down, and be damned throughout the ages.”

Henry IV installed his personal chaplain, Tedald, as Bishop of Milan; unfortunately, another priest of Milan, Atto, had already been chosen in Rome by the pope. In 1076 Pope Gregory responded by excommunicating Henry, removing him from the Church and declaring him depose as German king and HRE.

Enforcing these declarations was a different matter, but the advantage gradually came to be on the side of Pope Gregory. German princes and the aristocracy were happy to hear of the king’s deposition. They used religious reasons to continue the rebellion started at the First Battle of Langensalza in 1075, and for seizure of royal holdings. Aristocrats claimed local lordships over peasants and property, built forts, which had previously been outlawed, and built up localized fiefdoms to secure their autonomy from the empire.

Thus, because of these combining factors, Henry IV had no choice but to back down, needing time to marshal his forces to fight the rebellion. In 1077 he traveled to Canossa in northern Italy to meet the Pope and apologize in person. As penance for his sins, he dramatically wore a hairshirt and stood in the snow barefoot in the middle of winter. Gregory required that he kneel in the snow. Gregory lifted the excommunication, but the German aristocrats, whose rebellion became known as the Great Saxon Revolt, were not so willing to give up their opportunity. They elected a rival king. But Henry was far from done.

Henry IV then proclaimed Antipope Clement III to be Pope. In 1081 Henry IV captured and killed the rival king, and in the same year he invaded Rome with the intent of forcibly removing Gregory VII and installing anti-pope Clement. Gregory VII called on his allies, the Normans in southern Italy, and they rescued him from the Germans in 1085. The Normans sacked Rome in the process, and when the citizens of Rome rose up against Gregory he was forced to flee south with the Normans. He died soon thereafter.

The Investiture Controversy continued for several decades as each succeeding Pope tried to diminish imperial power by stirring up revolt in Germany. These revolts were gradually successful. Henry IV was succeeded upon his death in 1106 by his son Henry V, who had rebelled against his father in favor of the papacy, and who had made his father renounce the legality of his antipopes before he died. Nevertheless, Henry V chose one more antipope, Gregory VIII for which he was excommunicated by Rome. Later, Henry V renounced some of the rights of investiture with the Concordat of Worms, abandoned anti-pope Gregory, and was received back into communion and recognized as legitimate Holy Roman Emperor as a result.

To the side of all this, a similar controversy was active in England. Problematically, the pope needed support of the English King Henry I against the German Henry and thus downplayed the English practice of investiture. Eventually, this too was settled in the Concordat of London (1107). The Concordat suggested a compromise that was taken up in the Concordat of Worms. In England, as in Germany, a distinction was being made in the king’s chancery between the secular and ecclesiastical powers of the prelates (Bishops, Abbots, etc.). Employing the distinction, Henry I gave up his right to invest his bishops and abbots and reserved the custom of requiring them to come and do homage directly from his hand for the “temporalities” (the landed properties tied to the episcopate). This required the bishop to swear homage and feudal vassalage in a ceremony like any secular vassal.

This will be in effect for 500 years when the age of the Reformation(s) arrives.