On 25 June 1080, a synod convened at Brixen by Henry IV, Holy Roman Emperor ⓘ declared Gregory VII ⓘ  deposed and elected Guibert of Ravenna as pope under the name Clement III.

The council formed part of the escalating conflict between imperial and papal authority during the Investiture Controversy ⓘ. Henry IV, already excommunicated by Gregory, sought to assert imperial influence over the Church by sponsoring a rival claimant to the papacy.

Although Clement III never secured universal recognition, his election marked a decisive stage in the struggle between reform papacy and imperial power. In 1084 he would crown Henry IV emperor in Rome.