The Holy Roman Empire is the longest-lived political institution in European history and it is, simultaneously, the one that gives historians the most trouble. The standard chronological frame puts its foundation at the coronation of Otto I in Rome on the 2nd of February 962 and its dissolution at Francis II's abdication on the 6th of August 1806 — eight hundred and forty-four years. The institution itself, however, has at least three plausible foundation dates (Charlemagne in 800, Otto I in 962, and Frederick Barbarossa's official adoption of the "Holy" prefix in 1157), at least four different territorial definitions across its history (Carolingian, Ottonian, Staufer-era, post-Westphalian), and no continuous capital city, head of state by primogeniture, defined national church, single language of administration, or central treasury. Voltaire's famous dismissal of 1761 — "neither holy, nor Roman, nor an empire" — has the rhetorical merit of provocation, but it gets the substance wrong on every count.
Charlemagne's coronation
The story begins, conventionally, on Christmas Day in 800, when Pope Leo III crowned the Frankish king Charlemagne — Karl der Große, Carolus Magnus — as Imperator Romanorum in old St Peter's Basilica in Rome. The event has been disputed by historians since the ninth century. Einhard, Charlemagne's biographer, claimed that Charlemagne had not known the coronation was coming and that he would not have entered the basilica had he known — a claim that is almost certainly Einhard's literary invention. The political circumstances were intricate: Leo had been the victim of a Roman aristocratic conspiracy in April 799, had been beaten and (in the chronicles' formula) had his eyes put out and his tongue cut out, had been rescued and restored by Frankish-allied agents, and was substantially dependent on Charlemagne for his continued tenure. The coronation legitimised Leo as much as it legitimised Charlemagne. From the Byzantine perspective in Constantinople, where Empress Irene was at the time the sole reigning ruler, the western coronation was a usurpation: there could not be two Roman emperors, and the legitimate one was the Greek-speaking one in the East.
Charlemagne's empire — the Frankish realm extending from the Pyrenees to the Elbe, from the Atlantic to the Danube and central Italy — was the largest unified political entity in western Europe between the fifth-century collapse of the Western Roman Empire and the Napoleonic conquests of 1805–1812. It was administered through a complex layered system: counts (comites) responsible to the emperor governed the local pagi; missi dominici toured the country auditing the counts; the imperial chapel — the capella — at Aachen provided the central chancery, the legal scholarship of the Carolingian renaissance, and the schools. The empire was, in the deepest substantive sense, a personal achievement of Charlemagne's: it depended on his energy, his diplomatic relationships with the Church, and his military authority over the Frankish nobility. When he died at Aachen on the 28th of January 814, the empire passed intact to his son Louis the Pious. It would not survive Louis's death.
The Carolingian dissolution
The Treaty of Verdun of 843 divided the Carolingian empire among Louis's three surviving sons — Lothair (Italy and a north-south "middle kingdom" from Frisia to Rome), Louis the German (eastern Frankia, the lands east of the Rhine that would later become Germany), and Charles the Bald (western Frankia, the lands that would later become France). The division was the consequence of Frankish inheritance custom — which treated kingdoms as patrimonial property to be partitioned among heirs rather than as continuous institutions to be passed intact — combined with the political weakness of Lothair, who had been the original sole heir but had lost the brothers' civil war of 840–842. The "middle kingdom" of Lotharingia disintegrated within a generation, its territories partitioned between the eastern and western Frankish realms over the course of the ninth and tenth centuries. The Carolingian imperial title was held by varying combinations of the family until 924, after which it lapsed.
Otto's coronation
The institution that would become the Holy Roman Empire was created — or perhaps recreated, depending on whether one takes 800 or 962 as the foundation date — by Otto I, duke of Saxony and king of East Frankia. Otto's father Henry the Fowler had been elected king at Fritzlar in 919 in the wake of the East Frankish Carolingian extinction; Henry had pursued a conventional policy of consolidating the East Frankish duchies (Saxony, Franconia, Bavaria, Swabia, and Lotharingia) under royal authority. Otto, succeeding in 936, extended this in two directions: military authority over the rebellious dukes (the Battle of the Lechfeld in 955 broke the Magyar raids that had destabilised central Europe for fifty years), and political authority over the Italian kingdom (he intervened in Italian affairs in the 950s on behalf of the widowed Italian queen Adelaide, married her, and was crowned King of Italy at Pavia in 951).
On the 2nd of February 962, in Rome, Pope John XII crowned Otto and Adelaide as emperor and empress. The coronation has been treated, since the late tenth century, as the foundation of the Holy Roman Empire — the moment at which the imperial title returned to a Frankish-Germanic ruler after a 38-year vacancy. The substantive innovation of 962 was the formalised relationship between the emperor and the Roman Church: the Privilegium Ottonianum of 962 confirmed papal sovereignty over the patrimonium Petri but reserved to the emperor the right to confirm papal elections and to receive an oath of fidelity from the new pope. The arrangement worked, in essence, for about a hundred and ten years. The collision with reformed eleventh-century papal claims — the Investiture Controversy under Gregory VII and Henry IV in the 1070s — is the subject of the next chapter.
The shape of the Ottonian Reich
The Ottonian and early Salian empire — Otto I (936–973), Otto II (973–983), Otto III (983–1002), Henry II (1002–1024), Conrad II (1024–1039), Henry III (1039–1056) — was the most cohesive period of imperial authority the institution would ever experience. The emperor governed through an itinerant court that moved between the imperial palaces of Aachen, Magdeburg, Quedlinburg, Goslar, Speyer, Regensburg, and the Italian residences at Pavia and Rome. Royal authority depended on the personal relationships between the emperor and the great magnates — the dukes of the stem duchies (Saxony, Bavaria, Swabia, Franconia, Lotharingia), the archbishops of Mainz, Cologne, Trier, and Magdeburg, and the bishops of the major imperial sees. The bishop-prince — the Reichsbischof — was a particular institutional innovation of the Ottonian-Salian period: bishops, who could not legally pass their offices to heirs, were appointed by the emperor and rewarded with secular jurisdiction over substantial territories, becoming reliable counterweights to the hereditary lay nobility. The Reichskirchensystem — the imperial-church system — was the principal administrative mechanism of the eleventh-century empire. Its collision with the reformed papacy, which would refuse to accept lay investiture of bishops, is the great twelfth-century crisis the next chapter narrates.
By the death of Henry III in 1056, the empire was at the apex of its medieval power. The young Henry IV, six years old at his father's death, would inherit it. The collision was about to come.
End of Chapter I