Emperor Louis the Pious died, triggering a struggle among his surviving sons—especially Emperor Lothair I versus Louis the German and Charles the Bald—over whether the empire would remain unified or be partitioned.
In the civil war, Louis the German defeated and killed Lothair’s commander Adalbert of Metz at the Ries, enabling Louis to link up with Charles the Bald for the larger campaign against Lothair.
The allied forces of Charles the Bald and Louis the German defeated Lothair I (and his ally Pepin II of Aquitaine) at Fontenoy. The battle became the decisive military turning point pushing the brothers toward negotiated partition.
Charles the Bald and Louis the German swore mutual military oaths against their brother Lothair I. The text is also famous for preserving early forms of Romance and Germanic vernaculars.
The brothers agreed to divide the empire: Charles received West Francia, Louis received East Francia, and Lothair retained the imperial title and received a central kingdom (Middle Francia). This settlement is a foundational moment in the political geography of later medieval Europe.
Soon after Verdun, Charles the Bald issued the Treaty/Capitulary of Coulaines with West Frankish nobles and clergy, affirming protections for their offices and property in exchange for loyalty—an important step in stabilizing his post-partition rule.
The Treaty of Prüm partitioned Middle Francia among Lothair I’s sons, creating separate political units (including Italy under Louis II and Lotharingia under Lothair II) that reshaped the post-Verdun order.
As Lothair I’s health failed, he renounced active rule and entered the monastery of Prüm, setting the stage for the division of Middle Francia among his sons.
Lothair I died at Prüm shortly after his abdication and the Prüm partition, leaving the imperial title and Middle Frankish lands to be contested and reconfigured among his heirs and brothers.
After the death of Lothair II (king of Lotharingia), his uncles Charles the Bald and Louis the German agreed at Meerssen to divide Lotharingia, further dismantling the Middle Kingdom created at Verdun.
Emperor Louis II (Lothair I’s eldest son) died near Brescia. His death reopened competition for the imperial title and influence in Italy among other Carolingian rulers.
With papal support, Charles the Bald went to Italy and was crowned emperor in late 875, briefly reuniting the imperial title with the West Frankish line after Louis II’s death.
Civil Wars and the Treaty of Verdun: Partitioning the Empire (840–875)
