Saxon revolt of 1077–1088 in the context of Rudolf of Rheinfeld

Otto of Nordheim (c. 1020 – 11 January 1083) was Duke of Bavaria from 1061 until 1070. He was one of the leaders of the Saxon revolt of 1073–1075 and the Saxon revolt of 1077–1088 against King Henry IV of Germany.

Godfrey of Bouillon (c. 1060 – 18 July 1100) was a preeminent leader of the First Crusade, and the first ruler of the Kingdom of Jerusalem from 1099 to 1100. Although initially reluctant to take the title of king, he agreed to rule as prince (princeps) under the title Advocatus Sancti Sepulchri, or Advocate of the Holy Sepulchre.

He was the second son of Eustace II, Count of Boulogne in present day France. He received an inheritance from his mother's family in 1076 when he became Lord of Bouillon, which is now in Belgium. In 1087, Emperor Henry IV also confirmed him as Duke of Lower Lorraine, in reward for his support during the Great Saxon Revolt.

The Synod of Brixen was a church council held on 15 June 1080 in the episcopal city of Brixen. It was convoked by King Henry IV of Germany at the height of the Investiture Controversy to pass judgement on Pope Gregory VII. The synod issued a decree condemning the pope, demanding his abdication and authorizing his deposition if he refused. The synod also elected his successor, Wibert of Ravenna.

Henry IV was at war with a rival claimant to the kingship, Rudolf of Rheinfelden. At the time of the synod, Rudolf had won a recent victory at the battle of Flarchheim on 27 January 1080. In the aftermath of the battle, Henry sent Archbishop Liemar of Bremen and Bishop Rupert of Bamberg to Rome to confer with Gregory at his annual Lenten synod. Rudolf too sent envoys to Rome. On 7 March, the synod chose to recognize Rudolf as the legitimate king. On 13 April, Gregory VII pronounced Henry excommunicated and gave him until 1 August to repent, else "he would die or be deposed". In response Henry convoked the synod of Mainz that met on 31 May. It recommended removing the pope and electing another.