How did the Ordinatio Imperii attempt to preserve the unity of the Carolingian Empire?

The Ordinatio imperii, issued by Louis I in 817, was a strategic blueprint designed to reconcile the centrifugal pressures of regional autonomy with the need for imperial cohesion. It attempted to preserve the unity of the Carolingian Empire by establishing a clear hierarchy of succession while simultaneously providing for the emperor's sons.12

Under this decree, the empire was divided into three subordinate kingdoms: Lothar I was designated as coemperor and sole heir to the imperial title, while his younger brothers, Pippin and Louis the German, were assigned the kingdoms of Aquitaine and Bavaria, respectively. To ensure unity, these younger brothers were required to remain under the general suzerainty of Lothar, effectively maintaining the empire as a single political entity under the overarching authority of the eldest son. By formalizing these roles, Louis sought to prevent the fragmentation of the empire that often resulted from traditional dynastic inheritance practices.312