The Byzantine Exarchy in NE Italy came to a definitive end with the Lombard conquest of Ravenna in 751.
Deusdedit was the fourth doge of Venice, ruling from 742 to 755, but we know little more about him than of the previous doges and the “magistri militum”.
Venice was an independent state for almost a millennium, but it might note have been. It all hinged on a single battle fought in the Venetian lagoon in 810.