GEBARDO III, bishop of COSTANZA. - Son of Duke Bertoldo I Zähringen; provost at Xanten, then a Benedictine monk at Hirsau, he was consecrated bishop of Costanza on 22 Dec. 1084 by Ottone di Ostia, the future pope Urbano II. A vigorous defender of ecclesiastical rights, during the struggle over investitures he was appointed by Pope Urbano II apostolic vicar for Germany together with Bishop Altmanno of Passavia.
In 1089 he consecrated the new cathedral of Costanza; in 1094 he held a great council; in 1095 he took part in the papal Synod of Piacenza. From 1109-1105 he was obliged to yield to a bishop set up against him by Enrico IV. In 1105, commissioned by Pope Pasquale II, he absolved Enrico V from excommunication and subsequently accompanied him to Saxony, where he intervened in political and ecclesiastical negotiations. In 1106 he went as a member of Enrico V’s legation to Pope Pasquale II.
In the last years of his life, G. withdrew from politics and devoted himself exclusively to his diocese.
He died on 12 Nov. 1110.