Lotharius I, imperator Imperii Romanorum (817-855)

Emperor Louis the Pious and his son Lothar write to Venerius, the patriarch of Grado, confirming the possessions of his Church, including the Patriarchate's jurisdictions in Istria.

Louis the Pious and his son Lothar instruct Patriarch Venerius of Grado to go to Rome again to settle his dispute with the Patriarch Maxentius of Aquileia before the Pope and their messengers, despite the fact that Maxentius failed to attend the first meeting, causing Venerius to return home without any resolution.

Emperor Lothair I confirms the immunities enjoyed by the Church of Aquileia and its right to canonically elect their patriarchs.

The first pact between the Venetian neighbors in the Kingdom of Italy, represented by Emperor Lothar I, and the Duchy of Venice, represented by Doge Pietro Tradonico, sanctioning mutual aid in campaigns against the Slavs, defining the rights over the use of land and numerous aspects related to trade as well as the modalities of justice administration.

Emperor Lothar I confirms the Venetian possessions in the Empire.

A poem composed in response to the Synod of Mantua (6^th of June, 827), arguing that Aquileia, the old metropolitan see of the ecclesiastical province Venetia et Histria, was so thoroughly destroyed by barbarians (Attila, the Avars, Lombards and Goths) that it was never rebuilt; thus, the metropolitan see transferred to "the Venetians" and Aquileia was demoted to a status of a mere parish.

Pope Sergius II writes to Andrew, the patriarch of Aquileia, addressing his ongoing dispute with Venerius, the patriarch of Grado, urging patience, suggesting the convening of a general synod to address these issues, and emphasizing the need for imperial authority to finally put an end to this dispute between the two ecclesiastical sees.

Pope Leo IV writes to Victor, the patriarch of Grado, conferring upon him the pallium.

King Henry IV confirms the rights and possessions enjoyed by the Patriarchate of Aquileia, especially the parish (!) of Grado, bestowed upon the Patriarchate by Henry's predecessors and the Holy See.