Pope Gregory III’s Appeal to Charles Martel (c. 739 AD): Forging the Papal Frankish Alliance

by HistoriaRomana | Jul 25, 2026 | History, Medieval Rome, Politics

In the tumultuous early 8th century, as the Byzantine grip on Italy loosened and the Lombard kingdom exerted increasing pressure, a critical diplomatic maneuver set the stage for centuries of European history. Around 739 AD, Pope Gregory III, facing existential threats from King Liutprand of the Lombards, made an unprecedented decision: he dispatched an embassy to Charles Martel, the powerful Mayor of the Palace of the Franks, appealing for military intervention and protection. This desperate plea marked the nascent stages of what would become a pivotal Papal Frankish Alliance, fundamentally shifting the geopolitical loyalties of the Roman papacy from the distant, iconoclastic Byzantine emperor to the emerging Carolingian dynasty in the West. This strategic pivot not only underscored the Papacy’s growing autonomy but also laid the very foundations for the future Holy Roman Empire and redefined the relationship between temporal and spiritual power in medieval Europe, setting a precedent for future papal reliance on Frankish might against Italian threats.

The Shifting Sands of Italian Power in the 8th Century

By the early 8th century, the political landscape of Italy was undergoing a profound transformation. The once formidable Byzantine Exarchate of Ravenna, representing Constantinople’s authority in the peninsula, was in a state of terminal decline. Its military resources were stretched thin, and its focus was increasingly drawn to internal disputes, particularly the escalating Iconoclastic Controversy initiated by Emperor Leo III. This religious schism deeply alienated the Roman Papacy, which staunchly defended the veneration of icons, further weakening any perceived loyalty or reliance on the Eastern Emperor.

Into this vacuum stepped the formidable Lombard Kingdom. Under King Liutprand (r. 712–744 AD), the Lombards had consolidated their power across much of northern and central Italy, frequently clashing with and annexing territories from the Byzantine Exarchate. Liutprand harbored ambitions of uniting all of Italy under Lombard rule, which inevitably brought him into direct conflict with the autonomous Duchy of Rome and the Papacy itself. Rome, though nominally under Byzantine suzerainty, effectively functioned as a papal state, with Pope Gregory III leading its defense and administration amidst an increasingly hostile environment.

Pope Gregory III’s Desperate Appeal

Faced with relentless Lombard aggression, Pope Gregory III found himself in an untenable position. The Byzantine emperor, far from offering aid, was pursuing policies (like Iconoclasm) that exacerbated the Pope’s difficulties and even threatened his spiritual authority. Recognizing the futility of relying on Constantinople, Gregory III made a radical and unprecedented move. Around 739 AD, as Liutprand’s forces again menaced Rome and captured key strongholds, the Pope dispatched an embassy across the Alps to Charles Martel, the powerful Frankish Mayor of the Palace.

This appeal was laden with symbolic gravity, carrying the keys to St. Peter’s tomb and a direct plea for military intervention. Gregory III requested that Charles Martel act as the protector of the Roman Church, offering him the title of ‘patricius Romanorum’ (Patrician of the Romans), a prestigious honor previously associated with Byzantine authority. This act unequivocally signaled the Papacy’s strategic pivot, turning its gaze away from the weakening East and towards the ascendant power of the Franks in the West. It was a desperate gamble, but one that held the potential to secure the Papacy’s temporal and spiritual independence.

Charles Martel’s Response and the Seeds of a New Era

Charles Martel, fresh from his decisive victory over the Umayyads at the Battle of Tours in 732 AD, was undoubtedly the most powerful figure in Western Europe. However, his immediate response to Pope Gregory III’s appeal was not direct military intervention in Italy. Charles had his own complex political relationships, including a prior alliance with Liutprand against shared enemies, and he was deeply engaged in securing his own frontiers and consolidating Frankish power within Gaul and beyond.

While Charles did not march south to rescue Rome in 739 AD, his reception of the papal envoys and the diplomatic exchange itself were profoundly significant. The acknowledgement of the Papacy’s plight and the establishment of a direct communication channel laid crucial groundwork. It demonstrated that the Franks, unlike the Byzantines, were receptive to papal pleas for protection. This initial contact was the seed from which the formidable Papal Frankish Alliance would blossom. It paved the way for Charles Martel’s son, Pepin the Short, to intervene decisively against the Lombards in 754 and 756 AD, leading to the ‘Donation of Pepin’ and the formal establishment of the Papal States. Ultimately, it culminated in the coronation of Charlemagne, Pepin’s son, as Emperor in Rome in 800 AD, a moment that fundamentally reshaped medieval European politics and resurrected the idea of a Western Roman Empire under Frankish patronage.

Frequently Asked Questions

What prompted Pope Gregory III to seek Frankish help?

Pope Gregory III appealed to Charles Martel primarily due to the severe and persistent military threat posed by the Lombard King Liutprand, who was aggressively expanding his kingdom in Italy and threatening Rome. Simultaneously, the Byzantine Emperor Leo III, embroiled in the Iconoclastic Controversy, offered no assistance and was seen as a religious adversary, making reliance on Constantinople futile.

Who was Charles Martel and why was he chosen?

Charles Martel was the powerful Mayor of the Palace of the Franks, effectively the ruler of the Frankish Kingdom, renowned for his military prowess, most notably his victory over the Umayyads at the Battle of Tours in 732 AD. He was chosen because he commanded the strongest military force in Western Europe capable of challenging the Lombards, and he was a fellow Latin Christian, unlike the distant and religiously contentious Byzantine emperor.

Did Charles Martel immediately send aid to Pope Gregory III?

No, Charles Martel did not send immediate military aid to Pope Gregory III in 739 AD. While he received the papal envoys and maintained diplomatic contact, he was preoccupied with other conflicts and had existing ties with the Lombards. However, this initial diplomatic exchange laid the vital groundwork for future Frankish interventions in Italy.

What were the long-term consequences of this appeal?

The long-term consequences of Pope Gregory III’s appeal were immense. It fundamentally shifted the Papacy’s political orientation from Byzantium to the Franks, leading to the ‘Donation of Pepin’ which established the Papal States, and ultimately culminated in the coronation of Charlemagne as Emperor in 800 AD. This established the enduring Papal Frankish Alliance, creating the foundation for the Holy Roman Empire and shaping the political and religious landscape of medieval Europe for centuries.