From the time of Constantine I's conversion to Christianity in the 4th century, the question of the relationship between temporal and spiritual power was constant, causing a clash between the Church and the Empire. The decline of imperial power initially allowed the pope to assert greater independence. However, beginning in 962, the Holy Roman Emperor assumed control over papal elections and the appointment of bishops, reinforcing imperial authority over the Church.
In response to this, the Gregorian Reform commenced in the mid-11th century. By 1059, Pope Nicholas II had transferred the election of the pope to the college of cardinals. In 1075, Gregory VII proclaimed the dictatus papae, asserting papal supremacy and removing bishops from imperial appointment. This initiated a period of conflict known as the Investiture Dispute, highlighted by Henry IV's excommunication and his subsequent penance at Canossa. At the end of this conflict, the Pope succeeded in freeing himself from imperial guardianship. In 1122, under the Concordat of Worms, the Emperor agreed to the free election of bishops, reserving the right to give prelates temporal investiture. This compromise marked the defeat of the Empire.
The issue of Church and state relations reemerged during the reigns of Frederick Barbarossa and Frederick II, escalating into more intense confrontations. Despite significant weakening of the Holy Roman Empire during this time, the Papacy faced challenges in its attempts to establish a global theocracy. The conflict with the Holy Roman Empire would be succeeded by a new one with the Kingdom of France which forced the Pope to resettle to Avignon and later escalated in the Western Schism and Italian Wars.
The theocratic temptation
In the 12th century, following the Gregorian Reform, the Holy Roman Emperor lost the ability to control papal elections, leading to a resurgence of the Roman nobility's attempts to reclaim their former privileges. This power struggle intensified with the death of Pope Honorius II, resulting in clashes among various Roman factions.
The death of Henry V in 1125 marked the end of the Salian dynasty at the head of the Holy Roman Empire. The new emperor, Lothaire of Supplinburg, was known for his loyalty to the Papacy. The Pope called upon Lothaire to assist in countering the claims of Roger II of Sicily, who posed a threat to papal territories.
On February 1, 1130, Pope Innocent II was elected, but some of the cardinals elected an antipope, Cardinal Pierleoni, who took the name of Anacletus II. Threatened by Anaclet's schism, which lasted 8 years, Innocent II regained his power only with the support of France, England and the Emperor.
Over time, the Papacy began to interpret Lothaire's actions—initially seen as gestures of deference—as signs of the Empire's submission. In Liege in 1131, Lothaire took the pope's horse by the bridle, and in 1133, he was presented with a ring signifying that he took Tuscany from the Holy See. Papal propaganda depicted Lothaire as the pope's squire, with frescoes showing him humbly kneeling to receive a crown from Innocent II.Lothaire de Supplinbourg (ou de Saxe) within Atrium.
In 1139, Innocent II organized the second Lateran Council, asserting the Papacy's aspiration for global authority and its claim over the imperial crown. The Council proclaimed: "Rome is at the head of the world",Sentence quoted in . reinforcing the developing theocratic doctrine that subordinated secular affairs to spiritual authority.
In Italy, Arnold of Brescia defended the idea of total poverty and wanted to force the Pope to renounce all his temporal powers. Although condemned for heresy in 1140, he joined a republican revolt that drove the pope and his cardinals out of Rome in 1145. Rome was plagued by endemic power struggles. Pope Eugene III had to resort to force, and thus to Emperor Frederick Barbarossa. At Konstanz in 1153, the two men signed an agreement. In exchange for the Pope's reconquest of the Papal States, he agreed to crown Barbarossa emperor. Rome was recaptured in 1155. Barbarossa was crowned by Adrian IV the day after he entered the city, on June 18, 1155.Anne Ben Khemis, Frédéric Barberousse, Encyclopædia Universalis, DVD, 2007. Despite this exchange, tensions between the Papacy and the Empire persisted, and Rome remained unstable. The Pope, claiming dominium mundi, struggled to maintain control over his capital.
The situation escalated when, in 1157, at the Diet of Besançon, where the Pope's legate, Orlando Bandinelli (later Pope Alexander III), stated that "Rome is so well disposed towards Frederick that it would grant him even greater beneficia". The term "beneficia" can mean both benefit and fief, implying a potential subservience of the Emperor to the Pope. This declaration nearly resulted in the legate's death, as it was perceived as an affront in the feudal context. This incident marked the rupture between the Papacy and Frederick Barbarossa, initiating a more violent phase in the struggle between the Church and the Empire.
The Pope's aspirations for dominium mundi faced challenges beyond the Empire; in England, King Henry II successfully maintained control over the English Church, while some clerics within the Church questioned the superiority of papal authority over that of secular princes.
The conflict between Frederick Barbarossa and the Pope
During this period, two prominent factions were engaged in conflict within the Holy Roman Empire: the Guelphs, and the Ghibellines. The Guelphs, whose name is derived from the Bavarian ducal family, supported the Papacy, while the Ghibellines, named after Waiblingen, the ancestral fief of the Hohenstaufen dynasty, backed the Emperor.
Frederick wanted to restore imperial power. The revival of Roman law enabled him to revive the idea of the state and the superiority of the power of the temporal sovereign. He was supported in his fight against the Holy See by his chancellor, Rainald of Dassel, who urged him to break with the papacy,Encyclopædia Universalis, article « Allemagne médiévale ». and by German princes and prelates. Through a bold interpretation of the Concordat of Worms, he succeeded in taking control of the German clergy. Frederick asserted control over the German clergy, claiming the right to intervene in episcopal elections when disputes arose among electors. He also withheld temporal investiture from candidates he deemed unacceptable. As a result, he was able to impose his will in Augsburg in 1152, Worms in 1153, and even on the Pope in Magdeburg in 1154, effectively re-establishing bishops and abbots as "imperial officials." This jeopardized the balance of power established by the Concordat.
Frederick further asserted that the selection of the sovereign, viewed as divinely chosen, was the prerogative of the Empire's nobility, thereby diminishing the Pope's role in this process. After resolving issues within Germany, Frederick traveled to Italy in 1154, convening a Diet in Roncaglia to address grievances from Italian cities regarding Milan's dominance. In retaliation for its support of Milan, Frederick ordered the destruction Tortona.
In 1159, Alexander III was elected pope by a narrow majority of the conclave.
An antipope, Victor IV, was immediately elected, supported by the emperor. Alexander III had to flee Italy and took refuge in France. Open conflict erupted when Frederick Barbarossa sought to impose the imperial tax on Italian cities, which they refused. In 1162, Milan was destroyed and its inhabitants dispersed. This provoked the alliance of a number of towns to form the Lombard League, supported by Alexander III. Frederick Barbarossa had a new antipope elected each time the previous one disappeared. From the Würzburg Diet of 1165 onwards, all bishops in the Holy Roman Empire owed obedience to the antipope. Alexander III excommunicated the Emperor.
In 1167, Frederick's forces captured and pillaged Rome. However, with the army decimated by plague, he was forced to withdraw. At Legnano in 1176, he was defeated by the Italian cities. In 1177, he traveled to Venice, where he publicly submitted to the Pope and renounced his involvement in the papal elections. As a result, Alexander III lifted the excommunication against him, and Frederick agreed to serve as the Pope's squire. This reconciliation highlighted the potential benefits of cooperation between the Papacy and the Empire. Ultimately, Frederick's military losses, the impact of excommunication, and the rebellion of Italian cities thwarted his ambitions in Italy, at least temporarily.
In 1179, Pope Alexander III convened the Third Lateran Council to address issues stemming from the ongoing schism. To prevent further divisions, the council established that the pope would be elected by a two-thirds majority of the cardinals.
During this period, Emperor Frederick Barbarossa sought to reinforce his control over the Kingdom of Italy. He negotiated agreements with Italian cities and refused to return the inheritance of Tuscany, originally bequeathed to the Holy See by Matilda of Tuscany. Frederick also continued to appoint bishops and abbots in Germany, disregarding the original intent of the Concordat of Worms.
In 1186, Frederick married his son to the heiress of the Norman kingdom of Sicily, Constance, daughter of William II of Sicily. This union posed a geopolitical threat to the Papacy, as it indicated a potential encirclement of Papal influence.
After Frederick's accidental death during the Third Crusade, his son Henry VI prolonged the conflict with the Papacy over the question of Sicilian inheritance. After the death of William II, the Norman nobility chose Tancred, nephew of Constance, as king, with papal support. However, Tancred's reign was short-lived, and upon his death in 1194, Henry VI seized Sicily, refusing to swear vassalage to the Pope for his Norman possessions. He aimed to integrate Sicily into his empire but died before he could fully implement his plans.
This series of events led to the formation of urban leagues in Italy, such as the Lombard League, usually supported by the pope, and struggles between the Guelphs and the Ghibellines. After the death of Frederick II in 1250, the Holy Roman Empire entered a period of anarchy, the Great Interregnum from 1250 to 1273.
During this time, a political doctrine known as Caesaropapism gained prominence, advocating for the fusion of spiritual and temporal powers under the emperor, specifically the Emperor of the West. Although elements of this doctrine were evident during the Investiture Controversy, it became a focal point of political discourse during the Great Interregnum. In contrast, the Papacy emphasized theocratic governance, asserting that the Pope should hold both spiritual and temporal authority, thereby subordinating civil power to religious power. This clash of ideologies highlighted the persistent and opposing nature of the relationship between popes and emperors.
The conflict between Frederick II and the Pope
In 1198, Lothaire de Segni was elected Pope under the name of Innocent III. He supported the idea that the pope alone possessed full sovereignty (the auctoritas of the Romans), while princes held potestas, a political power granted to them directly by God. According to Innocent III, rulers were inherently subject to papal authority, as were national churches. His doctrine was more nuanced than the dictatus papae of the Gregorian reform, allowing for limited papal intervention in temporal matters under specific circumstances: grave sins committed by rulers, situations lacking other authoritative jurisdiction, and the defense of ecclesiastical property.
Innocent III sought to reassert his authority over Rome and his territories. He effectively dismantled the remnants of the Roman Republic by securing the resignation of the municipality and the dismissal of officials appointed by the republican senate.