What this all boils down to is that most of the northern subalpine region was conquered and under the subjugation of a powerful German imperial power called the Holy Roman Empire, or what eight centuries later the German National Socialists would refer to as the "First Reich."
Rather than take this sitting down, the city-states of the newly occupied region formed an alliance called the "Lombard League" to oppose the Germanic empire. They were literally fighting for their freedom, just as some of their ancestors had done six centuries earlier when the small Winnili tribe chose to stand and fight the powerful Vandal horde rather than accept being slaves. The odds going into this war were just as long as well.
The Holy Roman Empire was a union of territories in Central Europe during the Middle Ages and the Early Modern period under a Holy Roman Emperor. The first emperor of the Holy Roman Empire was Otto I, crowned in 962. The last was Francis II, who abdicated and dissolved the Empire in 1806 during the Napoleonic Wars. It was officially known as the Holy Roman Empire of the German Nation by 1450.
The Empire's territorial extent varied over its history, but at its peak it encompassed the Kingdom of Germany, the Kingdom of Italy and the Kingdom of Burgundy; territories embracing present-day Germany (except Southern Schleswig), Austria (except Burgenland), Liechtenstein, Switzerland, Belgium, the Netherlands, Luxembourg, the Czech Republic, Slovenia (except Prekmurje), as well as significant parts of modern France (mainly Artois, Alsace, Franche-Comté, Savoie and Lorraine), Italy (mainly Lombardy, Piedmont, Emilia-Romagna, Tuscany, and South Tyrol), and present-day Poland (mainly Silesia, Pomerania, and Neumark). For much of its history the Empire consisted of hundreds of smaller sub-units, principalities, duchies, counties, Free Imperial Cities, as well as other domains. Despite its name, for much of its history the Empire did not include Rome within its borders.
Holy Roman Emperor (from Wikipedia):
The Holy Roman Emperor is a term used by historians to denote a Middle Ages ruler, who as German King had in addition received the title of "Emperor of the Romans" from the Pope of the Holy Roman Church, and after the 16th century, the elected monarch governing the Holy Roman Empire, a Central European union of territories in existence during the Medieval and the Early Modern period. Charlemagne of the Carolingian Dynasty was the first to receive papal coronation as Emperor of the Romans. Charles V was the last Holy Roman Emperor to be crowned by the Pope. The final Holy Roman Emperor-elect, Francis II, abdicated in 1806 during the Napoleonic Wars that saw the Empire's final dissolution.
The standard designation of the Holy Roman Emperor was "August Emperor of the Romans." When Charlemagne was crowned in 800, his was styled as "most serene Augustus, crowned by God, great and pacific emperor, governing the Roman Empire," thus constituting the elements of "Holy" and "Roman" in the imperial title. The word Holy had never been used as part of that title in official documents. The word Roman was a reflection of the translatio imperii (transfer of rule) principle that regarded the (Germanic) Holy Roman Emperors as the inheritors of the title of Emperor of the Western Roman Empire, a title left unclaimed in the West after the death of Julius Nepos in 480.