The Emperor, on his part, had no reason to love his Western neighbours. The Popes had robbed him of the Exarchate of Ravenna: they had set up a Headship of the Church in Rome deaf to the claims of Constantinople. When in the eighth century the Emperor Leo, the Isaurian,[12] earned the nickname of ‘Iconoclast’, or ‘Image-breaker’, by a campaign of destruction amongst devotional pictures and images that he denounced as idolatrous, Rome definitely refused to accept this ruling on behalf of Western Christendom. This was the beginning of the actual schism between the Eastern and Western Churches that had been always alien in their outlook. In the ninth century the breach widened, for Pope Nicholas I supported a Patriarch, or Bishop of the Eastern Church, deposed by the Emperor and excommunicated his rival and successor, while subsequent disputes were rendered irreconcilable in the middle of the eleventh century when the Patriarch of Constantinople closed the Latin churches and convents in his diocese and publicly declared the views of Rome heretical. Besides the Pope at Rome the Eastern Empire possessed other foes in Italy. Chief of these were the Normans, who, not content with acquiring Naples, had, under the leadership of Robert Guiscard and his son Bohemund, captured the famous port of Durazzo on the Adriatic and invaded Macedonia. From this province they were only evicted by Alexius Commenus after wearying campaigns of guerrilla warfare to which his military ability was better suited than to pitched battles or shock tactics. [Sidenote: The Venetian Republic] More subtly dangerous than either Pope or Normans was the commercial rivalry of the merchant cities of the Mediterranean, Pisa, Genoa, and Venice. It was Venice who from behind her barrier of islands had watched Attila the Hun lead away his armies in impotent rage.[13] It was Venice again who of the North Italian states successfully resisted the feudal domination of Western Emperors and kept her own form of republican government inviolate of external control. It was the young Venice, the ‘Queen of the Adriatic’ as her sons and daughters proudly called her, that could alone in her commercial splendour and arrogance compare with the dying glory of Constantinople. Alexius Commenus in his struggles against Robert Guiscard had been compelled to call twice upon Venice for the assistance of her fleet; but he paid dearly for this alliance in the trading privileges he was forced to grant in Eastern waters. Wherever in the Orient Venetian merchants landed to exchange goods they were quick to establish a political footing; and the world mart on the Adriatic, into which poured the silks and dyes, the sugar and spices of Asia, built up under the rule of its ‘Doges’, or Dukes, a national as well as a commercial reputation. In 1095 necessity spurred Alexius Commenus to appeal not merely to Venice for succour but to Pope Urban II and all the leading princes of Western Europe.