charlemagne's gov't broke up soon after his death because of?

Question

feuds and internal wars among his successors
the inability of the gov't to pay its expenses
the inceasing luxury of the court
-or- quarrels between the gov't and the church?

Answer 1

Feuds and internal wars among his successors. The Carolingians, like the Merovingians before them, did not believe in primogeniture (where the eldest son inherits the entire knigdom) so territories were split upon the ruler's death. In this case, it happened after Charlemagne's son died and his grandsons split the kingdom three ways.