From: City of Fortune: How Venice Ruled the Seas, by Roger Crowley (Random House, 2012), Kindle Loc. 335-379:
For four hundred years the Adriatic itself had been ruled from Rome; for another six hundred the sea, and Venice itself, had been subject to Rome’s Greek-speaking successor, the Byzantine emperors in Constantinople. By the year 1000, this power was starting to wane, and the Venetians were engaged in a stealthy act of substitution. In the small stone cathedrals of Zara, Spalato, Istria, and Traù, the Venetian doge was remembered in prayers only after the name of the emperor in Constantinople, but this practice was, simply, a ritual. The emperor was far away; his power no longer stretched much north of Corfu, at the gates of the Adriatic, and along the Italian shore. The lords of Dalmatia were in all fact the Venetians. The power vacuum created by weakening Byzantine control would allow Venice to move up the scale progressively from subjects to equal partners and finally, in tragic circumstances, to usurpers of the Byzantine sea. The lords of the Dalmatian coast were embarked on the ascent.
The relationship between Byzantium and Venice was one of intense complexity and longevity, chafed by mutually contradictory views of the world and subject to wild mood swings, yet Venice always looked to Constantinople. This was the great city of the world, the gateway to the East. Through its warehouses on the Golden Horn flowed the wealth of the wider world: Russian furs, wax, slaves, and caviar; spices from India and China; ivory, silk, precious stones, and gold. Out of these materials, Byzantine craftsmen fashioned extraordinary objects, both sacred and profane—reliquaries, mosaics, chalices chased with emeralds, costumes of shot silk—that formed the taste of Venice. The astonishing Basilica of Saint Mark, reconsecrated in 1094, was designed by Greek architects on the pattern of the Church of the Holy Apostles in Constantinople; its artisans recounted the story of Saint Mark, stone by stone, in imitation of the mosaic styles of Saint Sophia (Hagia Sophia); its goldsmiths and enamelers created the Pala d’Oro, the golden altarpiece, a miraculous expression of Byzantine devotion and art. The whiff of spices on the quays of Venice had been carried a thousand miles from the godowns of the Golden Horn. Constantinople was Venice’s souk, where its merchants gathered to make (and lose) fortunes. As loyal subjects of the emperor, the right to trade in his lands was always their most precious possession. He, in turn, used this privilege as the bargaining chip to rein in his uppity vassals. In 991 Orseolo gained valuable trading rights for Venetian support in the Adriatic; twenty-five years later they were tetchily withdrawn again in a spat.
Differing attitudes to commerce marked a sharp dividing line. From early on, the amoral trading mentality of the Venetians—the assumed right to buy and sell anything to anyone—shocked the pious Byzantines. Around 820 the emperor complained bitterly about Venetian cargoes of war materials—timber, metal, and slaves—to his enemy, the sultan in Cairo. But in the last quarter of the eleventh century the Byzantine Empire, such a durable presence in the Mediterranean basin, started to decline, and the balance of power began tilting in Venice’s favor. In the 1080s the Venetians defended the empire in the Adriatic against powerful Norman war bands, intent on taking Constantinople itself. Their reward was sumptuous. With all the imperial pomp of Byzantine ritual, the emperor affixed his golden seal (the bulla aurea) to a document that would change the sea forever. He granted the city’s merchants the rights to trade freely, exempt from tax, throughout his realms. A large number of cities and ports were specified by name: Athens and Salonika, Thebes and Antioch and Ephesus, the islands of Chios and Euboea, key harbors along the coasts of southern Greece such as Modon and Coron—invaluable staging posts for Venetian galleys—but above all, Constantinople itself.
Here, Venice was given a prize site down by the Golden Horn. It included three quays, a church and bakery, shops and warehouses for storing goods. Though nominal subjects of the emperor, the Venetians had effectively acquired their own colony, with all the necessary infrastructure, in the heart of the richest city on earth, under extremely favorable conditions. Only the Black Sea, Constantinople’s grain basket, was barred to the avid traders. Quietly echoing among the solemn, convoluted lines of the Byzantine decree was the sweetest Greek word a Venetian might ever want to hear: monopoly. Venice’s jostling rivals in maritime trade—Genoa, Pisa, and Amalfi—were now put at such disadvantage that their presence in Constantinople was almost futile.
The Golden Bull of 1082 was the golden key that opened up the treasure-house of eastern trade for Venice. Its merchants flocked to Constantinople. Others started to permeate the small ports and harbors of the eastern seaboard. By the second half of the twelfth century, Venetian merchants were visible everywhere in the eastern Mediterranean. Their colony in Constantinople grew to around twelve thousand and, decade by decade, the trade of Byzantium imperceptibly passed into their hands. They not only funneled goods back to an avid market in continental Europe, they acted as intermediaries, restlessly shuttling back and forth across the ports of the Levant, buying and selling. Their ships triangulated the eastern seas, shipping olive oil from Greece to Constantinople, buying linen in Alexandria and selling it to the Crusader states via Acre; touching Crete and Cyprus, Smyrna and Salonika. At the mouth of the Nile, in the ancient city of Alexandria, they bought spices in exchange for slaves, endeavoring at the same time to perform a nimble balancing act between the Byzantines and the Crusaders on one hand and their enemy, the Fatimid dynasty in Egypt, on the other. With each passing decade, Venice was sinking its tentacles deeper into the trading posts of the East; its wealth saw the rise of a new class of rich merchants. Many of the great families of Venetian history began their ascent to prominence during the boom years of the twelfth century. The period heralded the start of commercial dominance.
With this wealth came arrogance—and resentment.