The Lombard kingdom in northern Italy seemed near the height of its powers in 770, but ended abruptly just four years later -- after King Desiderius imprudently thrust himself into a dynastic dispute among contending elements of the ruling Frankish dynasty centered at Aachen in present-day Germany. Charles I, King of the Franks, who was known as Charlemagne [Charles the Great], reacted swiftly, decisively defeating the Lombards at their capital of Pavia in the summer of 774.

The Franks divided the Lombard territory with the Pope at Rome, creating the Papal States. In 787 Pope Hadrian was induced to crown Charlemagne's son Pepin as King of Italy. Soon Charlemagne and Pepin moved to add Venice to their Italian possessions, first by diplomacy and then by open attack.