The Treaty of Verdun

843 CE — Europe, Carolingian Empire

Today: Verdun, France

Charlemagne's grandsons fought a civil war over his empire and settled it by cutting it into three: a west that became France, an east that became Germany, and a long strip between them that nobody could hold. Frankish custom divided a father's lands among his sons, which meant every succession dismembered whatever the last generation had assembled. The middle strip — Lotharingia, running from the Low Countries down through Alsace to Italy — dissolved into contested ground, and France and Germany fought over pieces of it for the next eleven centuries.

Worth knowing: The border drawn at Verdun in 843 is still, roughly, the border between France and Germany — and the strip left over between them, Alsace-Lorraine, changed hands four times between 1871 and 1945.

Pattern: Succession / legitimacy crisis — The orderly transfer of power fails because no rule or claimant is accepted as legitimate.

Entry 104 of 240 in Precedent, a walk through the whole human story in order.