Mâcon, who adhered to Boso, was forced to surrender, and the Carolingian kings, pursuing their advance without encountering any resistance, laid siege to Vienne where the usurper had fortified himself. The unlooked-for defection of Charles the Fat put a stop to the campaign. For a long time John VIII, compelled by the desertion of Boso to go back to the policy of an alliance with Germany, had been demanding the return of Charles to Italy. Suddenly abandoning the siege, the king again crossed the Alps in order to go to Rome and there to receive the imperial crown from the hands of the Pope (February 881) while his cousins, unable to subdue Boso at once, returned to their dominions, leaving the task of blockading Vienne to the Duke of Burgundy, Richard the Justiciar, who was own brother, as it happened, to the rebel king of Provence. Queen Ermengarde, who was defending the place, was obliged to surrender a few months later (September 882).
Charles the Fat made no long stay at Rome. As early as February 881 he took the road leading northwards. It is true that the new Emperor made a fresh expedition into Italy at the end of the same year, though he got no farther than Ravenna. Here the Pope came to meet him in order to try and obtain from him measures likely to protect the patrimony of St Peter from the attacks of the dukes of Spoleto. But the death of Louis of Saxony (20 January 882) now recalled the Emperor to Germany. This event made Charles master of the whole Eastern Kingdom, for Carloman of Bavaria, who by an agreement made in 879 with Louis had secured to the latter his whole inheritance, had died in 880. Carloman's illegitimate son Arnulf had been by the terms of the same treaty forced to content himself with the duchy of Carinthia. Hugh of Lorraine, who still under pretext of claiming his paternal heritage had again been indulging in acts of brigandage, had been defeated by Louis some time before his death and constrained to take refuge in Burgundy.
In the Western Kingdom, Louis III of France had died of a fall from his horse on 5 August 882. Carloman, summoned from Burgundy, received the magnates' oaths of fidelity at Quierzy and thus became the sole sovereign of the Western Kingdom. His brief reign is wholly taken with fruitless struggles against the Northmen. On 12 December 884 he also was carried off by an accident while out hunting. Louis the Stammerer's posthumous son, Charles, known later as the Simple, was by reason of his youth unfit to reign. Thus the Frankish nobles appealed to Charles the Fat, in whose hands were thus concentrated all the kingdoms which had gone to make up the empire of Charles the Great. But the Emperor, though a man of piety and learning, was very far from possessing the activity and vigour demanded by a position now more difficult than ever. For the ravages of the Northmen had redoubled in violence during the preceding years. Established permanently in Flanders, they took advantage of their situation to ravage at once what
