Treaty of Verdun

Setting the scene

Charlemagne's empire, forged through conquest, was too large to survive his dynasty's succession practices. When his son Louis the Pious died in 840, his three surviving sons—Lothair I, Louis the German, and Charles the Bald—fought a three-year civil war. Lothair, as eldest, claimed the entire empire as emperor, while his brothers allied against him. They defeated Lothair at the Battle of Fontenoy in 841, then sealed their alliance with the Oaths of Strasbourg in 842, sworn in both Old French and Old High German—the first documents in those vernaculars.

What happened

Exhausted, the brothers met at Verdun in August 843 to partition the empire. Lothair retained the imperial title and received Middle Francia—a long strip from the North Sea through the Low Countries, Burgundy, Provence, and northern Italy, including the imperial capitals Aachen and Rome. Louis the German took East Francia, roughly modern Germany. Charles the Bald received West Francia, roughly modern France. The division followed linguistic and cultural lines but created an unwieldy middle kingdom.

Why it still matters

The Treaty of Verdun ended Carolingian unity forever. Middle Francia, lacking geographic coherence, fragmented within a generation—Lothair's sons divided it further at Prüm in 855, and it eventually dissolved into the kingdoms that became the Netherlands, Belgium, Lorraine, Switzerland, and northern Italy. West and East Francia evolved into France and Germany, their rivalry shaping European history for a millennium. Verdun created the basic political map of Western Europe, establishing borders that echo today.【7851879941871381354†L5-L7】

Background

It shaped the political map of medieval France and Germany. Even centuries later, this episode remains a reference point for how empires rise, fracture, and transform.