It was convoked by King Henry IV of Germany at the height of the Investiture Controversy to pass judgement on Pope Gregory VII.
[2] 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.
On 13 April, Gregory VII pronounced Henry excommunicated and gave him until 1 August to repent, else "he would die or be deposed".
[1] The assembled prelates included 29 bishops from the Holy Roman Empire and one priest, Hugh Candidus, representing the College of Cardinals.
[1] The choice of Brixen (Bressanone) was based on the loyalty of its bishop, Altwin, to Henry IV's cause, as well as its geographical location.
The latest crime was that of the Lenten synod, in which he had approved of the death of the king and lent support to a traitor, Rudolf.
[4] The final sentence on Gregory was that he "should be canonically deposed and expelled and condemned in perpetuity, if, having heard this [decree], he does not step down.