It took place in Brittany, amongst those populations of Armorica who were still buried in their woods, and were excessively jealous of their independence.

In 818 they took for king one of their principal chieftains, named Morvan; and, not confining themselves to a refusal of all tribute to the king of the Franks, they renewed their ravages upon the Frankish territories bordering on their frontier.

Louis was at that time holding a general assembly of his dominions at Aix-la-Chapelle; and Count Lantbert, commandant of the marches of Brittany, came and reported to him what was going on.

A Frankish monk, named Ditcar, happened to be at the assembly: he was a man of piety and sense, a friend of peace, and, moreover, with some knowledge of the Breton king Morvan, as his monastery had property in the neighborhood.

Him the emperor commissioned to convey to the king his grievances and his demands.