Pepin, the son of Charles Martel — the hero of the Franks for his victory over the Saracens (Muslim invaders) — was born in 714. Pepin and his older brother Carloman were taught by the monks of St. Denis. When their father died in 741, the two brothers began to reign jointly in the capacity of Mayor of the Palace of the whole Frankish kingdom. Through the efforts of Carloman and St. Boniface — the tireless English monk and vassal of Rome — the Frankish church was brought under the power of Rome. When Carloman joined a monastery in 747, the way was left open for Pepin to seize power from the weak King Childeric, a descendent from Clovis and the last of the Merovingian kings. First dispatching Boniface to Rome, Pepin then sent a letter to Pope Zachary asking whether “the divine law did not permit a valiant and warlike people to dethrone an imbecile and indolent monarch” in favour of one that already rendered the most important service of the state. The pope, already privy to the details of the case, answered favorably, “He who lawfully possesses the royal power may also lawfully assume the royal title.” In this manner the champion of Rome became king, and the popes usurped the authority to dismiss and appoint rulers. From this time forth, Rome insisted that the French kings held their crown only by the authority of the pope.
It wasn’t long till the popes had a use for Pepin. In 754, Pope Stephen II, threatened by the king of the Lombards, called upon Pepin to come to his aid. The response was quick and led by Pepin himself. Victory was achieved, and Pepin transferred the sovereignty over the provinces in question to the bishop of Rome.
When the Lombards again encompassed Rome, Pope Stephen again appealed to Pepin. In his first letter he reminded King Pepin that he hazarded eternal condemnation if he did not complete the donation which he had vowed to St. Peter. A second letter followed. But the Franks still did not come to the rescue. Finally, the Pope addressed a letter to Pepin, as if from St. Peter himself! “I, Peter the apostle, protest, admonish, and conjure you, the most Christian kings, Pepin, Charles and Carloman, with all the hierarchy, bishops, abbots, priests and all monks; all judges, dukes, counts, and the whole people of the Franks. The mother of God likewise adjures you, and admonishes and commands you, she as well as the thrones and dominions and all the host of heaven, to save the beloved city of Rome from the detested Lombards. If ye hearken, I, Peter the apostle, promise you my protection in this life and in the next, will prepare for you the most glorious mansions in heaven, and will bestow on you the everlasting joys of paradise. Make common cause with my people of Rome, and I will grant whatever ye may pray for. I conjure you not to yield up this city to be lacerated and tormented by the Lombards, lest your own souls be lacerated and tormented in hell with the devil and his pestilential angels. Of all nations under heaven the Franks are highest in the esteem of St. Peter; to me you owe all your victories. Obey, and obey speedily; and, by my suffrage, our Lord Jesus Christ will give you in this life length of days, security, victory; in the life to come, will multiply His blessings upon you, among His saints and angels.” Eternal life was said to be dependent on obedience to the pope.
It was after the Nicene synod, and under the reign of Irene, that the popes consummated the separation of Rome and Italy from the Byzantine empire by transferring the western empire to Pepin’s son, Charlemagne. The battles of the Iconoclasts had generated various grievances between the west and east. By choosing Charlemagne over the Eastern Emperor, the Roman church would acquire a zealous advocate, the church would be united under a supreme head, and the conquerors of the West would receive their crown from the successors of St. Peter.
Pope Adrian soon had need for Charlemagne. Under his command in 775 the kingdom of the Lombards finally fell, and Charlemagne presented to the successors of St. Peter, by an absolute and perpetual grant, the kingdom of Lombardy. Though Charlemagne held the royal title, the popes were now sovereign pontiffs and the Lords of the city and territories of Rome. Not satisfied with the estates and tithes, Rome aspired for more. It falsely claimed that the emperor Constantine I had given the church of Rome supreme power over all the region of the West, and that it was Charlemagne’s duty to restore those lands which had been robbed from the church. By this forgery, the church also supported for her claim that the eastern emperors had usurped their authority over the west.
On Christmas day in 800, pope Leo III blessed Charlemagne, and proclaiming him emperor and Augustus. Through numerous campaigns (more than 50), Charlemagne’s kingdom was considerably enlarged — ostensibly in the name of Christianity. Indeed it was either death or baptism. Charlemagne’s conquest completely changed the face of Europe. Throughout the conquered land, the palaces of the bishops and abbots arose, and a feudal hierarchy was established. Charlemagne laid the foundation for the Holy Roman Empire, which was ultimately established in 962 with the coronation of the German King Otto I by pope John XII (though that term was not used till after Otto).