Meantime the internal politics of Venice had been steadily preparing the way for the approaching fusion at Rialto. The period from the election of the first doge to the appearance of the Franks was characterized by fierce struggles between Heraclea and Jesolo. At length the whole population agreed to fix their capital at Malamocco, a compromise between the two incompatible parties, marking an important step towards final fusion at Rialto.
That central event of early Venetian history was reached when Pippin resolved to make good his title as king of Italy. He turned his attention to the lagoon of Venice, which had been steadily growing in commercial and maritime importance, and had, on the whole, shown a sympathy for Byzantium rather than for the Franks. Pippin determined to subdue the lagoons. He gathered a fleet at Ravenna, captured Chioggia, and pushed on up the Lido towards the capital of the lagoons at Malamocco. But the Venetians, in face of the danger, once more moved their capital, this time to Rialto, that group of islands we now call Venice, lying in mid-lagoon between the lidi and the mainland. This step was fatal to Pippin's designs. The intricate water-ways and the stubborn Venetian defence baffled all his attempts to reach Rialto ; the summer heats came on; the Lido was unhealthy.
Pippin was forced to retire. A treaty between Charlemagne and Nicephorus (810) recognized the Venetians as subjects of the Eastern empire, while preserving to them the trading rights on the mainland of Italy which they had acquired under Liutprand.
The concentration at Rialto marks the beginning of the history of Venice as a full-grown State. The external menace to their independence had welded together the place and the people; the same pressure had brought about the fusion of the conflicting parties in the lagoon townships into one homogeneous whole. There was for the future one Venice and one Venetian people dwelling at Rialto, the city of compromise between the dangers from the mainland, exemplified by Attila and Alboin, and the perils from the sea, illustrated by Pippin's attack. The position of Venice was now assured.
The first doge elected in Rialto was Angelo Particiaco, a Heraclean noble, and his reign was signalized by the building of the first church of San Marco, and by the removal of the saint's body from Alexandria, as though to affirm and to symbolize the creation of united Venice.