The ideal of Latin Christendom united under a single, Carolingian, emperor remained a potent political force long after Louis the Pious' death in 840. But to it was added a second, equally significant political reality: the existence of several legitimate Carolingian kings, Louis' sons and grandsons. Churchmen urged them to rule in a spirit of fraternal love and co-operation, but all of them were intent upon securing and advancing their status, wealth, and retinue, especially at the expense of their fellow rulers. In this competitive climate Charles the Bald manoeuvred and fought to establish his rule over the West Frankish portion of the empire which his father had designated for him. His long reign, from 840 until 877, was marked throughout by fierce rivalry for land and lordship between himself and his brothers, nephews and sons. At stake were the loyalties of Frankish aristocrats, the rich Carolingian fiscal lands of the Rhineland, and the two imperial capitals of Aachen and Rome.

Carolingian imperial ambitions made themselves felt all the way from the centre to the periphery. Dealings with frontier regions provided an opportunity for lavish, ritual displays of hegemony over Danes, Slavs, Beneventans, and Bretons. There was always the possibility of extracting tribute and military assistance from these peoples. Moreover, restive subject peoples could be exploited to distract the attention and destabilise the power of a brother king, for in the second half of the ninth century, one man's opponent was invariably another's ally. So it was with the Bretons.