In the last ten years of the reign of John, the relations to southern Italy completely changed. There a period of troubles was followed by a new epoch of power and glory. Roger II united in his hands Sicily and southern Italy, and on Christmas Day, 1130, he was solemnly crowned in Palermo with the royal crown. Owing to the union of these two territories, Roger II became at once one of the most powerful sovereigns of Europe. It was a tremendous blow to Byzantium. The Emperor, theoretically still claiming some rights to the south Italian lands, considered the occupation of them by the Normans but temporary. The restoration of Italy was a favorite dream of the emperors of the twelfth century. The assumption of the royal title by Roger seemed an offense to the imperial dignity; to recognize this title would have been to give up all rights to the Italian provinces.
The sudden rise of Roger was undesirable not only to Byzantium, but also to the German sovereign, who had important interests in Italy. In view of the common danger, John II formed an entente, first with Lothar of Germany and after the latter's death, with Conrad III Hohenstaufen; somewhat later this developed into a real alliance between the two Empires. The main object of this entente and later alliance was to destroy the Norman power in Italy. This alliance became very important under John's successor, Manuel. If John failed to strike a blow at the power of Roger, he succeeded, at least, in preventing him from invading Byzantium. The subsequent wars of Roger with Manuel showed clearly that such a plan of invasion had hovered before his eyes. The most important parts of John's external policy in the West, then, were his attitude regarding the formation of the Sicilian kingdom and the creation of the alliance of the two Empires.