A reply to /u/Zethniti

This is a bit of a complicated answer. Formally speaking, the extent of the Kingdom of Italy shifted over time, in particular in the very confusing but fascinating early modern era. It used to comprise almost all of northern and central Italy, and at one point Holy Roman Emperors controlled Sicily and Naples even if they were not incorporated in the HRE. The theoretical lordship of the HRE Emperor over the Kingdom of Italy persisted over time, but their realistic control did not.

The Italians were an unruly bunch, what with their location south of the Alps, which made access and communication difficult. Not to mention, when the Swiss Confederation left the HRE, this made the link more difficult. Over time, the maintenance of influence required periodic intervention by the HRE Emperor, ranging from outright militarily (re-)conquest to a stern visit to discipline their subjects there. Thus, the 1300-1400s period saw a growing restlessness in Italy as the HRE crown was being fought over by the three great houses of Luxembourg, Wittelsbach, and Habsburg; not to mention the Swiss leaving the HRE. Italian subjects still claimed nominal fealty to their HRE overlords, but in practice this became symbolic. At the same time, the theoretical protection of HRE ceased to be effective, so the Kingdom of Italy's member states lost territory to the rising Republic of Venice and the Papal States.

This all changed when the Habsburgs not only strengthened their hold on the HRE imperial title, they also acquired the Mediterranean holdings of Spain's Crowns. In particular, Naples and Sicily came under Charles V through his grandfather Ferdinand II Aragon.

As I wrote here, Charles V was also able to obtain the Duchy of Milan, due to a power vacuum when the long-ruling Visconti family was displaced as Francis I of France started his Italian Wars. Charles appointed Sforza to be duke of Milan, but a succession crisis within the Sforza family led Charles V to claim the title for himself.

Fast forward to 1630 during the Thirty Years, we see the Duchy of Milan under control of the Spanish Habsburgs and the Austrian Habsburgs maintaining a strong interest in member states of HRE in Italy, and of course the theoretical claim to the Kingdom of Italy. As usual, the French intervened in yet another succession crisis, this time of the Duchy of Mantua, strategically placed in Lombardy. The French Duke of Nevers claimed the title, to the chagrin of both sides of the Habsburgs. A significant war was fought over this, that distracted Imperial forces from Germany to Italy, such that as Sweden's Gustav II Adolf entered the 30YW he faced a significantly reduced Imperial force in Germany.

As you know, the ending of the 30YW saw a significant curtailment of the powers of the HRE emperor, which by that point were the Austrian Habsburg. Thus, we saw a steady decline both in the prestige of the Kingdom of Italy and the pragmatic influence of the HRE emperor there.

So when you look at maps from the early modern period, you have to distinguish between the theoretical boundaries -- which often overlapped -- and the reality of the situation.

• J. D. Tracy, "Emperor Charles V, Impresario of War," ISBN-10: 0-521-81431-6, 2002.

• J. H. Elliott's "The Count-Duke of Olivares: the Statesman in an Age of Decline," ISBN-13: 978-0300044997.

• G. Parker, "The Thirty Years' War," ISBN-13: 978-0415128834, 1997.

• J. Lynch, "Spain under the Habsburgs," ISBN-13: 978-0814750094, 1984.

It's complicated. Very, very complicated. Feel free to ask follow ups if anything is confusing.

After the 8th-century Carolingan conquest, we can slice Charlemagne's empire in three parts, Western Francia (Modern France), Eastern Francia (Modern Germany) and the Middle Francia (Modern Belgium, Netherlands and Luxembourg, Switzerland, Burgundy and Italy).

Although there was a sort of "Crownsharing" deal among Charlemagne's descendants, the three kingdoms went their separate ways in by the 10th century: after the death without issue of Charles III the nobility of Eastern Francia did not let the throne pass to the king of Western Francia, but rather elected Henry the Duke of Saxony (setting a precedent for the electoral crown of the Holy Roman Empire). Henry's son Otto I was able to impose himself on Italy as well as Germany, as the landed nobility in Italy was so weak no internal pretender was able to hold on to the crown after Charles III.

Well-developed urban density, large agricultural surpluses in the fertile Northern Italian plain, and the presence of an influential clergy meant that small landowners were more inclined to attach themselves to an urban center as opposed to a large feudal overlord.

So immediately after the end of the Ottonian dynasty, eleventh-century Italian urban republics begin to assert themselves as polities independent of the Holy Roman Empie. Contrasts between the Empire and the Northern Italians would mean that even though technically North Italy was part of the empire, in order to assert their right rule in Italy, Holy Roman Emperors would have to cross the Alps with an army, and regardless of the outcomes the Italian cities secured increasingly favorable treaties, if they decided to obey them at all.

By the time the Italian cities solidified into the half-dozen early modern states during the renaissance, the traditional coronation of the Holy Roman Emperor by the Pope was little more than, well, a tradition. When, precisely you want to draw the line when the Italians ceased to consider themselves part of the empire is not something I get nitpicky about, but I'd settle for sometime between the thirteenth and fourteenth and centuries. Certainly when the Visconi were the dominant force in Italian politics in the early 15th century the Holy Roman Emperor was definitely not a player.

Technically at the dissolution of the Holy Roman Empire in 1806 in the midst of the Napoleonic Wars. However, Northern Italy (Lombardy, Milan, Trento etc.) were part of the Austrian Empire, which can be seen as a sort of continuance of the HRE as it was ruled by the Habsburgs.