Carolingian civil war in the context of "Partition of Verdun"

The Carolingian Empire (800–887) was a Frankish-dominated empire in Western and Central Europe during the Early Middle Ages. It was ruled by the Carolingian dynasty, which had ruled as kings of the Franks since 751 and as kings of the Lombards in Italy from 774. In 800 Pope Leo III crowned King Charlemagne as Roman emperor in return for political protection, disregarding the universalist claims of the weakened Byzantine Empire. The Carolingian Empire is sometimes considered the first phase in the history of the Holy Roman Empire.

After a civil war from 840 to 843 following the death of Emperor Louis the Pious, the empire was divided into autonomous kingdoms, with one king still recognised as emperor but with little authority outside his own kingdom. The unity of the empire and the hereditary right of the Carolingians continued to be acknowledged. In 884 Charles the Fat reunited all the Carolingian kingdoms for the last time, but he was deposed by the Frankish nobility in 887 and died in 888, and the empire immediately fractured. With the only remaining legitimate male of the dynasty a child, the nobility elected regional kings from outside the dynasty or, in the case of the eastern kingdom, an illegitimate Carolingian. The illegitimate line continued to rule in the east until 911, while in the western kingdom the legitimate Carolingian dynasty was restored in 898 and ruled until 987 with an interruption from 922 to 936.

The Treaty of Verdun (French: Traité de Verdun; German: Vertrag von Verdun), agreed to on 10 August 843, ended the Carolingian civil war and divided the Carolingian Empire between Lothair I, Louis II and Charles II, the surviving sons of the emperor Louis I. The treaty was the culmination of negotiations lasting more than a year. It was the first in a series of partitions contributing to the dissolution of the empire created by Charlemagne and has been seen as foreshadowing the formation of many of the modern countries of western Europe.

The treaty was the first of the four partition treaties of the Carolingian Empire, followed by the Treaties of Prüm (855), Meerssen (870), and Ribemont (880).

Lothair I (9th. C. Frankish: Ludher and Medieval Latin: Lodharius; Dutch and Medieval Latin: Lotharius; German: Lothar; French: Lothaire; Italian: Lotario; 795 – 29 September 855) was a 9th-century Emperor of the Carolingian Empire (817–855, with his father until 840) and King of Italy (818–855) and Middle Francia (843–855).

Lothair I was the eldest son of the Carolingian emperor Louis I and his wife Ermengarde of Hesbaye, daughter of Ingerman the duke of Hesbaye. On several occasions, Lothair led his full-brothers Pepin I of Aquitaine and Louis the German in revolt against their father to protest against attempts to make their half-brother Charles the Bald a co-heir to the Frankish domains. Upon the father's death, Charles and Louis joined forces against Lothair in a three-year dynastic war (840–843). The struggles between the brothers led directly to the breakup of the Frankish Empire assembled by their grandfather Charlemagne, and laid the foundation for the development of modern France and Germany.