A long period of eclipse for the patriarchate of Aquileia, which was now distinct from, and opposed to, Grado, had its end with Callistus. Maybe already with John, surely with Fortunatus [Fortunato] the patriarchal residence had been established in the safer, albeit marginal, ‘castrum’ of Cormons, where one after the other followed some patriarchs whose names are scarcely known, until Serenus ruled on the patriarchal cathedra of Aquileia between 715 and 730. This latter was no longer schismatic after the synod of Pavia (698), where the king Cunibert’s intervention had solved the question, and subsequently the see of Aquileia had also abjured. The refuge of Cormons was now evidently tight for the patriarchs who looked at Cividale as their new see. Even though the patriarch exerted his jurisdiction over, and at, Aquileia, he could not get the capital of the dukedom, Cividale, where the bishop of Zuglio, Fidentius, was apparently to prepare the recovery of a bishop see, which was certainly in the interest of the dukes («cum voluntate superiorum ducum») who usually resisted to the king’s authority stubbornly. In fact Callistus had been deacon of Treviso, not of Aquileia, and he had been chosen by the king Liutprand himself because he in all likelihood wanted to impose a loyal fellow of his to contrast duke Pemmo. Indeed when, after Fidentius’ death, Amator was ordained at Cividale, Callistus, «qui erat nobilitate conspicuus», did not tolerate that in his diocese another bishop could live with the duke and was granted power by the Lombard, while he himself «tantum vulgo sociatus vitam duceret». The tale is full of details in the Historia Langobardorum by Paul the Deacon of Cividale. Callistus then entered Cividale by force, expelled Amator and occupied his palace, but that arouse duke Pemmo’s reaction who, together with other Lombard nobles, arrested him and took him prisoner to the castle of Potium (perhaps Duino). King Liutprand then dismissed the duke and replaced him with his son Ratchis who had asked the king to forgive his father. Pemmo’s disproportionate reaction and the firmness of Liutprand’s behaviour make think of a merely political controversy, since there is no evidence of a papal intervention and also because Callistus’ arrival coincided with hated Pemmo’s removal and pious and devoted Ratchis’ advent. After arriving at Cividale in 737, Callistus provided for endowing the city with a palace for himself and his successors, who resided in the ducal city throughout the thirteenth century, and made his name be inscribed in the ciborium he erected in the centre of the baptistery that was placed in front of the old basilica, former cathedral, dedicated to the Mother of God. Beside reminding of Callistus as «beatus», the dedicatory inscription apparently echoes anti-Arian intentions in its recall of the “Trinitas vera”. Inserted in the ciborium plinth there is a pluteus with the name of Siguald, the patriarch who probably followed Callistus between 756 and 762.
For further information see the entry Callisto, patriarca d’Aquileia written by Sergio Tavano in Nuovo Liruti. Dizionario biografico dei Friulani, 1, Il Medioevo, edited by C. Scalon, Udine, Forum, 2006, 189-191.