Who Was Pope Leo III?

Pope Leo III (died 12 June 816) was the bishop of Rome from 795 to 816 and is best known for crowning Charlemagne emperor on Christmas Day 800. He was a Roman, born in a respectable family, who rose through the lower ranks of the Roman clergy. His pontificate was dominated by two great projects: defending the temporal claims of the Roman See against the Roman aristocracy and forging a new alliance with the Frankish king that would transform the political and religious map of the Latin West.

Early life and election to the papacy

Almost nothing is known of Leo III’s life before his election. He was born in Rome, probably in the 740s, and entered the Roman clergy at a young age. He served as a primicerius, one of the senior notaries of the Roman Church, and was a trusted administrator when, on 12 April 795, he was elected to succeed Pope Adrian I. His consecration two days later was the first papal election in the West to be marked by the presence of a Frankish embassy, sent by Charlemagne to confirm the choice of the Roman people and clergy. The presence of the embassy, sent in accordance with the agreement of 774 by which Charlemagne was patrician of the Romans, was the first sign of the new relationship between the Carolingian monarchy and the papacy.

The attack of 799

Leo III’s pontificate was troubled from the start. The Roman aristocracy resented the influence of the Frankish king in Roman affairs and were suspicious of the new pope, who had been chosen for his administrative ability rather than for his noble birth. In April 799, a group of Roman nobles, led by a cleric named Paschal and the relatives of the former papal administrator Campulus, attacked Leo in a street near the Lateran. They tried to gouge out his eyes and cut out his tongue, and they left him for dead. Leo was rescued by his attendants, escaped from Rome, and made his way north to the Frankish court, which was then at Paderborn.

The reception of Leo at Paderborn in the summer of 799 was a turning point. Charlemagne received the pope with the highest honors, treated him as a father in God, and listened to his account of the attack. The Frankish king did not immediately agree to escort Leo back to Rome, since the political situation in Italy was delicate. He did, however, send the pope north to the monastery of Fulda for safekeeping, and he convened a synod of Frankish bishops to discuss the case. The synod decided that the pope would have to clear his name in Rome, with the assistance of a Frankish embassy. Leo spent the winter in the Frankish realm, and in November 800 he returned to Italy with Charlemagne’s escort.

The synod of 800 and the coronation

The synod that met in St. Peter’s in late November 800 was a Roman assembly under Frankish supervision. Leo, having taken an oath to clear himself of the charges brought by his enemies, was allowed to purge himself by compurgation, a procedure in which he swore his innocence and was supported by a group of Frankish and Roman bishops. The procedure was unusual, since the Roman Church had traditionally held that the bishop of Rome could be judged by no one, but the political circumstances were exceptional. The assembly cleared Leo and confirmed him in office.

Three weeks later, on Christmas Day 800, Leo crowned Charlemagne emperor. The act is the most famous moment of Leo’s pontificate and the one on which his historical reputation chiefly rests. The coronation was not only a religious ceremony; it was a political act that bound the new emperor to the Roman Church and gave the pope a central role in the new imperial order.

The Donation of Leo III

In the years following the coronation, Leo III was forced to defend his position against a renewed opposition. The Roman aristocracy continued to claim that he had been irregularly elected, and the Byzantine court was hostile to the new imperial title. To strengthen his case, Leo promoted the legend of the Donation of Constantine, the supposed grant by which the emperor Constantine had given temporal power over Rome and the western Empire to Pope Sylvester I. The original Donatio Constantini is a forgery, almost certainly composed in the Frankish court in the late eighth or early ninth century, but Leo III accepted and used it.

The donation served Leo’s purposes well. It justified the territorial claims of the papacy in central Italy, which had been founded by Pepin the Short in 754 and confirmed by Charlemagne in 774. It also gave the pope a role in the imperial succession: if Constantine had given the western Empire to Sylvester, then the pope had a part in conferring imperial authority. The donation was used by the papacy for centuries and was only definitively exposed as a forgery in the fifteenth century by the humanist Lorenzo Valla.

Relations with Charlemagne

Leo’s relationship with Charlemagne was close but never simple. The pope needed the Frankish king to defend Rome from the Roman aristocracy, the Lombards, and the Byzantines. The king needed the pope to confer the imperial title and to legitimize his rule. The two men met repeatedly, exchanged letters, and treated one another with great respect. Charlemagne corresponded with Leo on theological as well as political questions, sending the pope his book on images, the Libri Carolini, for approval. The pope, in turn, sent the king relics, vestments, and the keys of St. Peter’s tomb.

Yet the two were not always in agreement. Leo’s eagerness to be crowned emperor was not shared by Charlemagne, who seems to have preferred the simpler title of king. The Libri Carolini, in which the king criticized the use of images in worship, were not approved by Leo, and the two men disagreed on the role of images in the Church. The disagreements were private, but they were real.

The legacy of Leo III

Leo III died on 12 June 816, having held the papacy for just over twenty years. He was buried in St. Peter’s, near the tomb of the apostle. His pontificate was one of the most important in the history of the Latin Church, for it established the model of a papacy that was both a spiritual and a political power, and it created the alliance with the Frankish crown that would shape European history for centuries.

The coronation of 800 was, in the long view, the founding act of the medieval Western Empire. The Donation of Constantine was the founding myth of the Papal States. The synod of 800 was the first in a long series of councils in which the papacy and the empire negotiated the boundaries of their respective authorities. All three acts were the work of Leo III.