What did Louis the Pious struggle to maintain after Charlemagne's death?

Louis the Pious faced significant challenges in maintaining the unity of the Carolingian Empire following Charlemagne's death. Charlemagne had created a vast and diverse empire that included various peoples and territories, bound together primarily through his strong leadership and military conquests. After Charlemagne passed away, the sheer size of the empire, coupled with differing local interests and identities among the subjects, made it difficult for Louis to keep the realm cohesive.

Louis's reign was marked by infighting among his sons and the turbulent relations with the nobility, which further complicated the effort to preserve the empire's integrity. The internal divisions that arose during his reign, such as the disputes over succession and territory, threatened to fracture the empire established by his father. As a result, the unity that Charlemagne had painstakingly built began to erode during Louis’s rule, highlighting the difficulties of maintaining control over such a vast realm without the strong, central authority that Charlemagne had provided.