Vol. 1: A seculo VI usque ad 803

Pope Gregory III orders Callistus, the patriarch of Aquileia who has received the pallium from the pope, to restitute Centenara and Musione, the possessions of the monastery of St. Mary in Barbana subject to the Patriarchate of Grado.

Pope Gregory III writes to Patriarch Anthony of Grado, inviting him and his suffragans to a synod that is to take place in Rome and assuring him of safe passage through Lombard lands.

Lombard King Aistulf defeats and captures Eutychius, the Exarch of Ravenna, conquering the Byzantine Exarchate in Italy and further expanding the Lombard Kingdom over Comacchio, Ferrara and Istria (narrative account from the Salerno Chronicle).

King Pepin the Short promises to Pope Stephan II military aid against the Lombards and the restitution of occupied lands in Italy to the dominion of the Roman Church, the so-called Promissio Carisiaca; 11^th-century forgery.

Patriarch John of Grado writes to Pope Stephan III, lamenting over the Lombard treatment of his subjects in Istria, the newly imposed levies, and the diminishing influence of his metropolitan see, asking the pope to send aid to Istria and reinforce the jurisdiction of his church to the detriment of the “perfidious Lombards”.

Pope Stephan III writes to all the bishops of Istria, reprimanding their insolence for consecrating each other, reminding them that they fall under the metropolitan jurisdiction of the Archbishopric of Grado, and threatening the bishops who fail to heed these warnings with excommunication.

Pope Stephan III writes to Patriarch John of Grado, reassuring him that he has the support of the Apostolic See in his struggles against the Lombards in Istria, reminding him that Istria is under the joint protection of the papacy and the Franks, and informing him that he has dealt with the Istrian bishops who refuse to recognize him as their metropolitan and who uncanonically appoint each other to their episcopal sees.

Pope Adrian I writes to Charlemagne, the King of the Franks and the Lombards, beseeching him to direct Duke Marcarius of Friuli to help reinstate the Istrian bishop Maurice – whose eyes have been gouged out by “the most abominable Greeks” – to his bishopric.

Late 8^th-century poem lamenting the destruction of Aquileia at the hands of the Huns in the mid-5^th century, composed either by Paulinus II of Aquileia (ⴕ 802) or Paul the Deacon; the poem was later used by Venetian authors to argue that Aquileia had never been restored following this destruction and that Grado, therefore, succeeded it as the capital of the ecclesiastical province of Venetia et Histria.

Narrative sources on the events of 788 that resulted, among a variety of other things, with Istria being incorporated into the Frankish kingdom.

King Charlemagne writes to his wife Fastrada, informing her, among other things, of their military successes against the Avars, including the achievements of his “duke of Istria”. This is the first documented mention of a Carolingian official in Istria, officially marking the beginning of a new era of the peninsula’s history.

King Charlemagne bestows to the Church of Aquileia the right to canonical election of their patriarchs (that nonetheless requires royal confirmation) and exempts it from public taxes such as the tithes, the grazing fees for livestock sent to graze in Istria, and war taxes (lodgings and provisions for the army) unless the royal military is forced to pass through Friuli and the Treviso region.

King Charlemagne confirms the possessions of the Church of Aquileia and grants it immunities.

A poem dedicated to the memory of the late Duke Eric of Friuli, composed by Patriarch of Aquileia Paulinus II.

Pope Leo III confers the pallium upon Fortunatus II, the incumbent patriarch of Grado.

Emperor Charlemagne subordinates six episcopal sees to the Church of Aquileia, badly damaged by the incursions of the pagans; late-10th-century forgery.

Emperor Charlemagne bestows immunities upon the Church of Grado due to the special services and merits of its incumbent Patriarch Fortunatus II.

Emperor Charlemagne exempts the four ships of Fortunatus II, "the patriarch of the Venetians and Istrians," from all the tolls.