Grado was the seat of the Patriarch of Aquileia (later Grado) from 606 until 1172 when the patriarch moved to Venice. It was also traditionally the northernmost point of the Dogado.
The dukes Obelerius and Beatus, and the war with the Franks, from the “Chronica per extensum descripta” (1340s) by Andrea Dandolo.
The account of the dukes Obelerius and Beatus, from the “Istoria Veneticorum” by John the Deacon.
Internal strife in Venetia led to the murder of a patriarch, and a change of government.