Venice (in Venetian: Venezsia, Italian: Venezia, Latin: Venetia) is a city in northern Italy, on the coast of the Adriatic Sea, that greatly impacted the history of the late Eastern Roman (Byzantine) Empire and of the Orthodox Church centered in its capital, Constantinople.
While there are no records of the founding of the city of Venice, available evidence leads historians to agree that Venice developed out of the movement of people (that is, refugees) from Roman cities in northern Italy who fled successive waves of barbarian invasions during the latter centuries of the Western Roman Empire. What remained after the Visigoth, Hun, and Lombard invasions of the fourth to sixth centuries was a strip of coastal Italian territory under the rule of the Eastern Roman Empire along the northern stretch of the Adriatic Sea. New port facilities were built in the Venetian lagoon at Malamocco and Torcello. By the middle of the eighth century, the dominance of the Eastern Empire had been eliminated, and early in the ninth century Agnello Particiaco, the local duke, had moved the ducal seat to the well-protected Rialto (from Rivolalto: High Shore) island, which is the current location of Venice.
As the city prospered and grew, the Monastery of St. Zachary, the first ducal palace, and a basilica to St. Mark were built. As the strength of Venice increased and Byzantine power waned, an anti-Byzantine character emerged that led to the growth of autonomy and eventual independence of Venice as a city-state. In 828, the prestige of the city was increased by theft of the relics of St. Mark the Evangelist from Alexandria, Egypt (except the head of the saint, which remains till this day in Alexandria, Egypt—the story is that the Venetian smugglers told the Muslims that they were just taking pickled pork out of the country). The relics were placed in the new Byzantine-styled basilica. Considerable Byzantine plunder from Constantinople was then brought back to Venice, including the Winged Lion of St. Mark, which became the symbol of Venice. In 1968, the Catholic Church returned part of the relics of St. Mark back to the Coptic Church in Egypt.video #1, video #2
From its strategic and almost invulnerable location at the head of the Adriatic Sea, Venice became a flourishing trade center between Western Europe and the eastern world of the Byzantine Empire and Islamic countries. During the twelfth century, Venice expanded its power over northern Italy to the eastern shore of the Adriatic and the islands of the eastern Mediterranean.
In 1204, Venice became an imperial power following the Fourth Crusade, which, under Venetian control and blackmail, seized Constantinople and established the Latin Empire. Venice herself carved out a sphere of influence known as the Duchy of the Archipelago. Unfortunately, the seizure of Constantinople by the Fourth Crusade would ultimately prove a decisive factor in the downfall of the Byzantine Empire after the empire lost the Anatolian themes following the Battle of Manzikert on August 26, 1071. Though the Byzantines recovered control of the ravaged city a half century later, the Byzantine Empire was effectively powerless and existed only as a ghost of its old self until Sultan Mehmet the Conqueror took the city in 1453.
With the events of 1204, the schism between the Catholic West and Orthodox East was complete.