The Carolingian Empire at Its Height

On Christmas Day of the year 800, Charlemagne knelt before Pope Leo III in St. Peter’s Basilica and was crowned Emperor of the Romans. The ceremony in Rome was more than a personal honour; it signalled the restoration of an imperial ideal that had lain dormant in Western Europe for more than three centuries. Charlemagne’s empire, forged through decades of conquest, stretched from the Pyrenees to the Elbe and from the North Sea to central Italy. It was a realm that melded Roman administrative memory, Christian universalism, and Germanic warrior culture into a single political order. For a brief moment, the dream of a unified Christendom under one temporal ruler seemed attainable.

Yet that unity was fragile. The Carolingian world rested on personal loyalty, military success, and the charisma of a single ruler. When Charlemagne died in 814, his sole surviving legitimate son, Louis the Pious, inherited the whole inheritance. Louis shared his father’s religious fervour but lacked the unassailable authority that came with founding a dynasty. From the start of his reign, the question that would dominate the ninth century loomed: how should a Christian empire be passed on to multiple sons without shattering the very idea of empire?

The Succession Problem and the Ordinatio Imperii

The Carolingians, like many Frankish dynasties, practised partible inheritance. Land and titles were divided among all legitimate sons. Charlemagne himself had intended to split his kingdom before the deaths of two of his sons left Louis as the lone heir. Louis the Pious, however, faced a different challenge. By 817 he had three sons from his first marriage—Lothair, Pippin, and Louis (later called “the German”)—and a fourth, Charles (the Bald), would be born to a second wife in 823. The arrival of Charles upset the delicate balance laid out in the Ordinatio Imperii of 817, an imperial decree designed to preserve the empire’s unity while providing for Louis’s older sons.

The Ordinatio was a revolutionary document. It named Lothair as co-emperor and principal heir, granting him the core Frankish lands and authority over his brothers. Pippin received Aquitaine and Louis received Bavaria, but both were to rule as subordinate kings under Lothair’s overarching imperial sovereignty. The scheme attempted to square the circle of Frankish custom and imperial ideology: one empire, one emperor, yet three kings. It collapsed because it ignored the fierce ambition of the younger brothers and the unpredictable realities of dynastic politics. When Louis the Pious tried to carve out a kingdom for young Charles in 829, rebellions erupted that would plague the remainder of his reign.

Civil War and the Battle of Fontenoy

Louis the Pious died in 840, and the vultures descended immediately. Lothair, as eldest and as co-emperor, claimed the whole empire as his own. He demanded that Louis the German and Charles the Bald acknowledge his supreme authority and surrender any autonomous rule. The two younger brothers refused. What followed was a three-way civil war that threatened to undo everything Charlemagne had built.

The pivotal military encounter came on 25 June 841 at Fontenoy-en-Puisaye, near Auxerre. The armies of Louis the German and Charles the Bald faced Lothair and his nephew Pippin II of Aquitaine. Contemporary chroniclers recorded the battle with horror. It was not an external raid but a slaughter of Frankish noblemen by their own kinsmen. The Annales Fuldenses lamented that “the flower of the Frankish people was cut down.” Fontenoy was a bloodbath that shocked the Carolingian elite and demonstrated beyond doubt that no single ruler could hold the empire together by force alone. Lothair, though not decisively crushed, was weakened enough that his brothers could dictate terms.

The Strasbourg Oaths and the Road to Verdun

In February 842, Louis and Charles met at Strasbourg and swore a remarkable oath of mutual support—not in Latin, the language of church and administration, but in the vernaculars spoken by their respective followers. Louis, whose power base lay in the Germanic-speaking east, swore in an early form of Old French so that Charles’s men could understand him. Charles reciprocated in Old High German for Louis’s troops. The texts of these oaths, preserved by the historian Nithard, are among the oldest surviving documents in the French and German languages. The Strasbourg Oaths were a political act, but they also nudged open a door onto a Europe where linguistic communities were beginning to map onto political loyalties.

The oaths left Lothair isolated. Over the next eighteen months, envoys shuttled between the warring brothers, and by August 843 a comprehensive settlement was hammered out in the city of Verdun. One hundred twenty commissioners were appointed, forty from each side, to survey the empire’s lands and recommend a partition that each king could accept as roughly equal. Their work produced the Treaty of Verdun, sealed on 10 August 843.

The Division of the Empire

The treaty carved the Carolingian realm into three kingdoms, each under a legitimate male-line descendant of Charlemagne. The division was not drawn along neat linguistic or ethnic lines—those categories were still fluid—but the new boundaries would profoundly influence the continent’s future.

West Francia: The Realm of Charles the Bald

Charles the Bald received the lands west of the Scheldt, Meuse, Saône, and Rhône rivers. This territory, roughly corresponding to most of modern France, included Neustria, Aquitaine, Gascony, Septimania, and the Spanish March (Catalonia). West Francia was predominantly Romance-speaking, with Gallo-Roman inhabitants and a Frankish military aristocracy that was gradually assimilating. Charles’s kingdom faced immediate challenges: Breton incursions on the western frontier, constant Viking raids along the Seine and Loire valleys, and the defiance of powerful regional magnates who had grown accustomed to operating independently during the civil wars.

East Francia: The Kingdom of Louis the German

East of the Rhine and north of the Alps, Louis the German took the bulk of the old Austrasian heartland, including Saxony, Thuringia, Alemannia, and Bavaria. This was a linguistically Germanic territory, though dialectal differences from north to south were substantial. Louis’s kingdom would later form the core of what became the medieval Kingdom of Germany and, ultimately, the Holy Roman Empire. The eastern frontier, bounded by the Elbe and the Danube, was subject to pressure from Slavs and, from the late ninth century, Magyar horsemen. Like his brother, Louis had to manage a restless nobility and the same decentralising forces that would eventually corrode Carolingian power everywhere.

Middle Francia: Lothair’s Strip of Kingdoms

Lothair, who retained the imperial title but little real authority over his brothers, was given a long, narrow strip of territory that ran from the North Sea to central Italy. It included the future Lotharingia (from which the name Lorraine derives), Frisia, the Low Countries, Alsace, Burgundy, Provence, and the Kingdom of Italy, with the imperial cities of Aachen and Rome at either end. This middle kingdom was a political puzzle. It had no geographical cohesion, no common language, and no shared identity. Instead, it was a buffer born of compromise—a place where the ambitions of all three brothers would continue to clash for decades.

Immediate Repercussions and the Erosion of Imperial Unity

The Treaty of Verdun was sold to contemporaries as a peace settlement that honoured Carolingian legitimacy while respecting the equal rights of three royal brothers. In practice, it launched a new era of internecine conflict. Lothair’s Middle Francia was the weak link: when he died in 855, his kingdom was partitioned among his own three sons by the Treaty of Prüm, fragmenting it further. By 870 the Treaty of Meerssen saw Charles the Bald and Louis the German divide much of Lotharingia between them, erasing the middle strip that had once separated their realms.

The decades following 843 saw a rapid dissolution of central authority. The Carolingians never again ruled a unified Western Europe. The title of emperor shrank to a dignity attached to one branch of the family, stripped of real pan-European command. Local counts, dukes, and margraves, many of whom had been royal appointees, turned their offices into hereditary fiefs. The great lay and ecclesiastical magnates built castles, collected taxes, raised private armies, and dispensed justice in their own names. The Viking raids of the late ninth century only accelerated this decentralisation. With a weak king unable to coordinate a rapid defence, communities looked to local strongmen for protection, accelerating the shift toward the feudal order that would characterise the High Middle Ages.

Long‑Term Consequences: The Birth of Nations

Historians have long regarded the Treaty of Verdun as a foundational moment in the formation of European nation-states. The borders drawn in 843 were not, of course, identical to those of modern France and Germany, but they set in motion a process by which distinct political and cultural identities could crystallise. Within a century, West Francia was being called Francia occidentalis and East Francia Francia orientalis, terms that gradually shed the Frankish modifier and evolved into “France” and “Germany.”

The linguistic dimension proved especially durable. The Strasbourg Oaths had already shown that ordinary soldiers spoke different vernaculars. By the tenth and eleventh centuries, the Romance dialects of the west and the Germanic dialects of the east were diverging into what we recognise as Old French and Old High German. The treaty did not cause this linguistic split, but by creating separate political frameworks it reinforced linguistic borders that would harden into national literatures, legal cultures, and administrative practices. When the Capetian dynasty established itself in France and the Saxon Ottonians rose in Germany, each kingdom already possessed a distinct self‑image rooted, in part, in the 843 settlement.

The middle kingdom, meanwhile, became Europe’s persistent borderland. The lands once held by Lothair—the Low Countries, Alsace‑Lorraine, Burgundy, and Italy—remained contested for over a thousand years. Students of modern European history will recognise these same territories as the fault lines of the Franco‑German rivalry that sparked conflicts from the Thirty Years’ War to the Second World War. The Treaty of Verdun, in that sense, began a long argument over the Rhine and the Alps that would not be fully resolved until the post‑1945 integration of Europe.

Reassessing the Myth of a “Carolingian Empire”

For generations, textbooks presented Charlemagne’s empire as a golden age of unity that was tragically shattered in 843. This narrative oversimplifies. The Carolingian Empire was never a centralised state in the modern sense. It was a confederacy of aristocracies held together by personal oaths, the charisma of a single family, and a shared Christian mission. The Treaty of Verdun did not invent regionalism; it codified what was already becoming the political reality—a world run by territorial magnates who needed a king but not an over‑mighty emperor.

Moreover, the treaty should not be seen as an anomaly. Partible inheritance had been the Frankish norm for centuries. The Merovingians divided their kingdom repeatedly, and Charlemagne himself had only avoided a full partition through the timely deaths of his sons. What makes Verdun significant is the scale and permanence of the division and the fact that it happened just as the empire was consolidating its institutions. The moment the crown could no longer command monopoly on violence and patronage, it lost the capacity to enforce unity. By 888, when Charles the Fat—the last Carolingian to rule all three kingdoms for a few brief years—was deposed, the centrifugal forces set loose in 843 were unstoppable.

Key Figures and the Choices They Made

The personalities behind the 843 treaty repay close study because their choices drove the narrative as much as any structural factor. Lothair I, born to be emperor, was unwilling to accept equality with his brothers, yet lacked the military resource to impose his supremacy. His stubbornness cost him the allegiance of many Frankish nobles who preferred partition to endless war. Louis the German proved to be a pragmatic survivor; he understood that a defensible eastern kingdom was worth more than a hollow imperial title. Charles the Bald, the youngest and initially the most vulnerable, turned out to be the most flexible diplomat. His patronage of learning and the church helped legitimise a western kingdom that was under perpetual military pressure.

These three men—grandsons of Charlemagne and sons of Louis the Pious—made a decision that shaped the destiny of hundreds of millions of people over the following twelve centuries. The treaty they signed in Verdun was not a peace of principle but a pragmatic truce among ambitious brothers. Yet it was precisely that pragmatism that gave it lasting force.

Verdun’s Place in Medieval Memory

Medieval chroniclers did not celebrate the Treaty of Verdun as a foundational charter. Regino of Prüm, writing at the end of the ninth century, famously observed that “after the death of Charles the Fat, the kingdoms that had obeyed him no longer chose a single ruler but each sought a king from its own entrails.” The treaty of 843 was the spark that, decades later, produced that world. In the twelfth century, when the Staufen emperors tried to rebuild a Mediterranean‑wide imperium, the ghost of Verdun still whispered in the ears of French and German kings who guarded their sovereignty jealously.

Understanding Verdun helps students move beyond simplifying labels like “the Dark Ages.” The ninth century was an era of violent dynamism, where whole peoples were on the move, where literacy was making a slow comeback, and where the shape of Europe was anything but inevitable. The treaty captures a moment when human agency—three men and their advisors poring over lists of counties, monasteries, and toll stations—directed the continent’s future.

Why the Treaty Still Matters

Today’s European Union, with its porous borders and shared sovereignty, might seem to be the antithesis of the 843 partition. But historical memory works in deep currents. The Treaty of Verdun is often invoked by scholars as the first major departure from antique imperial unity in the Latin West. It reminds us that political fragmentation is not a modern invention, that the tension between supranational ideals and local loyalties is perennial, and that the map of Europe has always been a palimpsest laid down by countless negotiations, wars, and accidents.

If we look at the linguistic boundary running through Belgium and Switzerland, at the continuing cultural distinctiveness of Catalonia and Lombardy, at the fiercely defended regional identities of Bavaria and Brittany, we see the faint after‑image of 843. The treaty did not create those identities, but it gave them a political framework in which they could grow. In that sense, the partition of the Frankish world was not an ending but a beginning—the moment when the medieval West truly began to become itself.

For further reading, consult resources such as the Encyclopædia Britannica entry on the Treaty of Verdun, the World History Encyclopedia overview of the treaty and its context, and the Oxford Reference summary of the Carolingian partitions.