The empire divided in 843 was for a brief period reunited under Karl the Fat from 884-887. But the failure of Karl either to enforce his authority in the empire or to protect its boundaries led to his deposition and to the definite division of the empire into small kingdoms under local rulers. Arnulf, an illegitimate son of Karlmann, the brother of Karl the Fat, became king of Germany; in France, as early as 879, Provence or lower Burgundy had elected a local count, Boso, as king; in 888, after the deposition of Karl the Fat, most of the French nobles elected Odo, duke of Francia, who belonged to the family of the counts of Paris, as their king, while upper Burgundy chose its own ruler in count Rudolf, and Aquitaine still held out under its duke for the young Charles the Simple, grandson of Charles the Bald. In Italy Charles the Bald, Ludwig, and Karl the Fat had attempted in vain to assert the authority of the emperor there, and Italy went its own way and became the field of battle between rival claimants for the crown, both of them local Italian nobles. Thus by 888 there were, including Aquitaine, six separate kingdoms, Germany, Italy, France, Aquitaine, Provence, and Burgundy.
Anno 879. Boso, on hearing of the death of Louis [the Stammerer], set out from Provence and undertook to seize the whole of Burgundy. And after he had won over several bishops to his cause by threats and persuasion, he proceeded to Lyon and there was anointed king over the Burgundian realm by Aurelian, the metropolitan of Lyon, and the other bishops. He ignored the young sons of Louis, treating them as illegitimate because their mother had been disgraced and put away at the order of Charles [the Bald]. But these youths, Louis and Carlman, were raised to the throne by abbot Hugo and the other nobles, and warred against Boso all their lives. Not only they but also the other kings of the Franks hated him for his usurpation, and made their dukes and vassals promise that they would try to overthrow and slay him.
Anno 887. In this year there died at Orleans abbot Hugo, who had held and ruled manfully the duchy [of Robert the Strong, _i.e._, Francia], and the duchy was given by the emperor to Robert's son, Odo, who had been up to that time count of Paris, and who, together with Gozlinus, bishop of Paris, had protected that city with all his might against the terrible onslaughts of the Northmen....