Investiture Contest This is the struggle for supremacy between the papacy and the secular rulers of Europe.

This controversy began in the 11 th and 12 th centuries from the church reforms initiated by Henry III, which came from his belief of there to have been a corruption of the church, such as the acts of Simony and Clerical marriage, and also his belief that his authority extended to the Church clergy and the investiture and deposition of bishops and archbishops, even to the bishop of Rome, the Pope.

Henry III set out to stop this corruption of the church and appointed a series of reform minded German popes. One of these reforming popes was Pope Leo IX ( ) who campaigned vigorously against simony and clerical marriage.

Another of these appointed popes was Hildebrand who became Pope under the name Gregory VII ( ). After the death of Henry III, a set of reformers including Pope Gregory VII asserted the Dictatus Papae which declared that the Roman church was founded by God alone - that the papal power was the sole universal power, also in this was the Papal Election Decree which stated that only cardinals could elect the pope and that only the pope could elect cardinals.

Henry IV also insisted on his authority as divinely appointed sovereign and reacted to this decree of Papal authority by sending a letter to Gregory VII a letter in which he withdrew his imperial support of Gregory as Pope, 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". It called for the election of a new pope. His 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 successfully drove Gregory from Rome and installed an Antipope. When Gregory heard of this he excommunicated Henry IV and declared he was no longer emperor and absolved his subjects from the oaths they had sworn to him. The excommunication of the King made a deep impression both in Germany and Italy.

After the excommunication of Henry IV, rival claimants to the throne started to rise which prompted Henry to try to gain his absolution from Gregory. At first he tried this by an embassy, but when Gregory rejected this, he went to Italy in person. Henry tried to force the Pope to grant him absolution by doing penance before him at Canossa.

Gregory lifted the excommunication, after this Henry IV broke many of his promises made in Canossa, as Henry IV proclaimed the Antipope Clement III to be Pope which led to the excommunication of Henry IV again. In 1081 Henry IV captured and killed Rudolf von Rheinfeld, a rival King elected by the German nobility and supported by Gregory after his victory at Flarchheim, this rebellion from the German aristocracy toward the king became known as the Great Saxon Revolt.

Henry IV then invaded Rome trying to forcibly remove Gregory VII and installing a more friendly pope. Henry, now in a much more powerful position than Gregory, gained surrender from Rome and Guibert of Ravenna was enthroned as Clement III (24 March 1084). Gregory was then forced into fleeing and did this through his allies the Normans in southern Italy.

The Investiture Controversy continued for many decades with each succeeding Pope wishing to diminish imperial power by stirring up revolt in Germany. But this controversy was concluded in the Concordat of Worms in which Henry IV's son, Henry V ( ), who rebelled against the views of his father in favour of the papacy and who had made his father renounce the legality of his antipopes before he died, forged a compromise between himself and Pope Calixtus II ( ).

In the Concordat, Henry V gave up lay investiture and the Pope conceded to the emperor the privilege of bestowing the symbols of territorial and administrative jurisdiction, this meant that Bishops and abbots were to be chosen by the clergy, but the emperor was to decide contested elections. Those selected were to be invested first with the powers and privileges of their office as vassal (granted by the emperor) and then with their ecclesiastical powers and lands (granted by church authority). This led to Henry V back into communion and recognized as legitimate Emperor as a result.