In the early eighth century, the Christian world outside Constantinople was sparsely scattered and doctrinally divided among Greek, Latin, Syriac, and Coptic churches. Rome, laid waste by multiple sackings and its aqueduct water supply system in ruins, was a shrunken shadow of its former self and under Byzantine protection. Latin Church missionaries were struggling to convert the barbarian European princes who ruled in the power vacuum left behind by the fallen Roman Empire. The conquests of Charlemagne and his crowning in 800 as the first Holy Roman Emperor still lay many decades in the future. Islam, by contrast, was still at the height of its explosive expansion following Muhammad’s death.
The only serious setback experienced by the Arab conquerors in the seventh century had been their previous failure in 674–679 to conquer Constantinople. Their overland attack had faltered when the Saharan camel proved unable to tolerate the cold of the Anatolian highlands of Turkey. Their sea attack had hinged on the success of its large siege engines and catapults against Constantinople’s double walls. It, too, failed when the Byzantines counterattacked by unleashing their terrifying, newly invented, secret chemical sea-warfare weapon—“Greek fire”—upon Arab ships. The chief characteristic of Greek fire was that it combusted spontaneously and fiercely upon contact with air and was inextinguishable even in water. The secret of its precise composition was lost during the Middle Ages and remains unknown today. It was a crude oil-based substance traditionally laced with sulfur, evergreen tree pitch or quicklime; by adding the right amount of saltpeter, the mixture became ferociously self-igniting. Only sand, vinegar, and urine were believed to dampen its smoky flames. Greek fire was usually blown by an air pump through long, bronze-lined tubes toward enemy ships, where it burst into flames; alternatively, it was catapulted at attacking ships in clay jars or fired in a hail of arrows that had been saturated in it. So many of the wooden hulls of the caliph’s vessels were set ablaze and so much terror inflicted upon Arab sailors by this unnerving weapon that in 679 the Muslims withdrew, and even agreed to pay an annual tribute to Constantinople. Greek fire not only saved the Byzantines, but its secret gave them a long-lasting military advantage in sea warfare that endured for a long time.
Yet the hard experience of 674–679 also meant that when the Arabs returned in 717 for their revenge assault, they came better prepared and in much greater force. Once again Constantinople’s defense hinged upon its supreme strategic location and sea power. The city’s position made it at once easily supplied through either of the two long, narrow straits—to the east by the Bosporus, 18 miles long and less than half a mile wide in some places, or by the 40-mile-long and one-to five-mile-wide Dardanelles on the west—connecting the Black and Mediterranean seas. On the northeast side of Constantinople’s peninsula, abutting the entrance to the Bosporus, was a wonderful, deep, five-mile-long harbor, the Golden Horn, which offered the only well-sheltered port in a turbulent stretch of sea. These natural geographical defensive advantages were reinforced by a great, half-mile-long chain across the harbor’s mouth that the Byzantines could raise to block the entrance. The city’s peninsular location meant that major fortification of walls and moat was needed only on its landward side. Its single defensive flaw was that it had only one good stream flowing into the Golden Horn to provide freshwater. To mitigate this vulnerability, Byzantine Roman water engineers had borrowed on the waterworks expertise of mother city Rome to build dams, a long-distance aqueduct, and giant underground cisterns within its walls to supply enough freshwater to withstand a siege.
The site, occupied since 658 BC by the prosperous Greek trading city of Byzantium, had been chosen, and renamed, by the Roman emperor Constantine I to replace beleaguered Rome as capital of the Roman Empire for its commanding strategic defensive and trading positions on the Black Sea. This “New Rome”—like the original it had seven hills, a bread dole for the poor, and a new Senate to entice the nobility to emigrate—was founded on AD May 11, 330. Moving to Constantinople had been one of Constantine’s two historic decisions. The second, inspired by his vision of a heavenly cross heralding his power-consolidating victory in the battle of the Milvean Bridge (AD 312) on the Tiber on the outskirts of Rome, was to adopt Christianity as the favored religion of the Roman Empire. In the life-and-death struggle against Islam (717–718), the fate of Constantine’s second great decision depended much on the strategic foresight of his first.
The fortunes of Constantinople and Christianity were improved in their hour of crisis by the seizure of the imperial throne a few months earlier by a gifted general, crowned as Emperor Leo III. The Muslim military strategy was to assault the city’s double walls from the landward side with a massive army, while two fleets bottled up the Dardanelles and the Bosporus to deny any supply relief from Mediterranean or Black Sea ports. The initial land attack, however, failed. So the Muslims settled in for a long siege to be waged, as in the late 670s, primarily on the water. This time they succeeded in sealing up the Dardanelles. The Bosporus proved more difficult. When the Muslim fleet approached Constantinople, its lead ships got caught up in swift, unfamiliar currents; Leo III promptly lowered the chain across the Golden Horn and struck the disoriented Muslim ships with Greek fire, destroying and capturing many of them.
Nature then assaulted the Muslim besiegers in their outdoor tents with an abnormally bitter winter. Their resupply was delayed. Famine and disease entered the camps, compelling the besiegers to eat their animals and even dead men’s flesh. As so often is the case in the history of warfare, noncombat causes claimed more lives than enemy weapons. The besiegers suffered the added indignity of having to dump many of their dead into the sea because snow froze the ground for many weeks to prevent burial.
When the warmth returned in the spring of 718, the Muslims’ luck turned. Reinforcements of 400 ships and 50,000 men arrived from Egypt. One night they succeeded in sneaking past the Golden Horn to complete the blockade that would doom the city and the Byzantine Empire. However, many of the Arabs’ Coptic Christian crew chose that moment to abandon their ships and desert to the Byzantines. Informed by their gift of priceless military intelligence, Leo III in June mustered a surprise counterattack with Greek fire that routed the blockading fleet. As Coptic Christian desertions mounted, Leo followed up with an unexpected land attack on the Asian side of the waterway. Caught off guard, thousands of Muslims were slaughtered. When, at Leo’s connivance, the neighboring Bulgars began to attack the Muslim forces, and rumors flew that the Frankish army was en route to join in, the caliph lifted the siege on August 15, 718, and retreated. By all accounts only 30,000 of the 210,000-man Islamic force, and only five out of its over 2,000 ships made it back home.
Constantinople was saved. That the city’s impregnability endured for another 500 years alongside a far wealthier and more vibrant Islamic civilization was testimony to the disproportionate military advantages of sea power and control of geostrategically important waterways. The city was finally sacked and effectively subjugated only in 1204—not by Muslims, but by fellow Christians diverted from their intended march to the Holy Land on the Fourth Crusade by the intrigues of the mercantile-minded sea power Venice and its redoubtable, blind, octogenarian doge, Enrico Dandolo. Venice thereafter exercised commercial hegemony over the straits, controlling the lucrative routes to the Black Sea. Constantinople finally fell to the Islamic Turks only in 1453.
The enormous consequences of Constantinople’s victory in 718 rippled through history for centuries. The first major effect was the survival of Christian Europe as a significant cultural and geographic rival to Islam. In 732 an expeditionary Muslim force from Spain was defeated by Frankish leader Charles Martel, grandfather of Charlemagne, on a battlefield near Poitiers, France, in what would later be regarded by Christian historians as heralding the turning point in ending the Arab Muslim land expansion in Europe. By 1097, Christian Europe was strong enough for its knights to cross the Bosporus from Constantinople and launch the successful counterattack to retake the Holy Land fro
m Islamic control—the First Crusade.
Christian Europe’s major gains against Islam were won principally through sea power. Constantinople’s triumph had ensured that the eastern Mediterranean, unlike its western half, never succumbed to Islamic dominance. Between 800 and 1000, both Muslim and Christian vessels vied for supremacy over the riches of the eastern Mediterranean, plundering where possible and trading when necessary. By 1000, the city-state Republic of Venice finally gained the upper hand as the great sea power and transshipper from the central Mediterranean to the rich ports of Alexandria and the Levant. Three centuries later, Genoese merchants broke the Islamic chokehold on the Strait of Gibraltar, opening the Atlantic sea-lanes to unify the Christian Mediterranean with the emergent world of northern Europe. From about the eleventh to sixteenth centuries, Christians increasingly controlled the Mediterranean while the Muslims reigned in the Indian Ocean. Thereafter, the “Voyages of Discovery,” motivated partly by the Portuguese’s and other Atlantic sea powers’ covetous desire to break the Italian and Muslim monopoly on trade with the East, culminated in a breakthrough all-sea route around Africa to India and momentously transformed the power relationships of world history with Europe at its center.
Islam’s gradual ejection from the Mediterranean following the defeat at Constantinople not only saved Christianity. It also had far-reaching effects within Islam itself. It set off a period of upheaval and renewal that reinvigorated Arab Islam by amalgamating it with older Near Eastern civilizations to help launch what proved to be its golden age. The defeat at Constantinople signaled the end of its juggernaut military expansion, which in turn upset the internal dynamics that had held together the growing fissures within the Islamic community. Previously, victory on the battlefield had yielded ample booty and tribute from defeated populations for distribution that had smoothed over internal rivalries among Arab tribes. With diminishing bounty to share, the tribal political system of Arab privilege run by the ruling Damascus-based Ummayad caliphate also began to fuel discontent among the growing number of non-Arab Muslim converts who increasingly supplied Islam’s manpower but often felt unwelcomed with second-class status.
In 750, the Ummayads were toppled in a civil war by a coalition led by a rival family descended from Muhammad’s uncle, Abbas. The Abbasids’ new caliphate was based on inclusion of non-Arab Muslims, governance that was comparatively professional and efficient rather than run on the basis of tribal patronage and nepotism, and religious universalism that encouraged converts with equal rights and opportunities. The new caliphate’s heartland was the productive, irrigated farmland of ancient Mesopotamia, where Arab conquerors had installed themselves as large landowners. The Abbasids’ commercial orientation shifted toward the east and the Indian Ocean. To celebrate their rise, they founded a new city—Baghdad—strategically positioned in a place where the Tigris and Euphrates rivers flowed near one another. This location gave the city convenient access to abundant irrigated food from the muddy floodplains and intersected major trade routes to Persia and the East. It was in Abbasid Baghdad that a great Islamic civilization first began to flourish. From 762 to 1258, when it was destroyed by the Mongols, Baghdad was the largest and grandest city anywhere outside China.
While Islamic civilization was not notably innovative in water engineering, in its ascendant period it vigorously applied known Middle Eastern technologies to get the most from its freshwater-scarce habitats. Water management thus played a key role in sustaining the power and splendor of the caliphate. Old waterworks were restored and new ones constructed. Muslim irrigation had its greatest success around Baghdad, where five dam-fed, cross country canals running from the Euphrates to the Tigris watered extensive, productive cropland. East of the Tigris, Abbasid engineers expanded the Nahrwan Canal that had been started by the Sassanian Persians in the second century AD. Water released from a famous masonry dam on Iran’s Kur River that was rebuilt in about 960 irrigated large fields of sugar, rice, and cotton.
The diffusion of Middle Eastern water technologies and crops supported the spread of high Islamic civilization across the Muslim world. Underground qanats increased domestic water supplies, while water-lifting norias and shadoofs supplemented field irrigation across North Africa and in Spain. Low-level diversion dams were widespread in Muslim Spain and became an important acquisition of the Christian kings when they later expelled the Muslims from Spain.
Grand cities arose that competed with Abbasid Baghdad culturally and politically. Cordoba, lying inland on the river Guadalquiver, became the seat of a brilliant humanistic Islamic civilization in Spain presided over for a long period by the lone dynastic Ummayad family survivor of the Abbasid purge that followed the civil war. The river irrigated the surrounding plains and provided the means for transporting food and goods to Cordoba’s marketplace. The tenth century saw the rise of a dazzling new city, Cairo, from which the Shiite Fatimids asserted their claim to the Islamic caliphate. The economic basis of Fatimid power was the fertile farmlands of the Nile and the extensive sea trade and camel routes through the Levant and Red Sea. By the early 1300s, Ibn Battutah, the renowned fourteenth-century Muslim traveler and diarist sometimes called “Islam’s Marco Polo,” marveled that because of its great size “in Cairo there are twelve thousand water-carriers who transport water on camels” throughout its sprawling network of streets and markets.
The grand Muslim cities like Cordoba, Cairo, Baghdad, and Granada, situated in hot, dry lands, displayed Muslim splendor and power by building sumptuous palaces, surrounded by shaded gardens with fountains and running water suggestive of paradise, and public baths as in ancient Rome. Wherever practicable in Islam’s stream-poor landscape, Muslim engineers exploited waterpower to grind flour in traditional mills as well as to produce new products and goods. Floating water mills operated day and night on the Tigris River to produce Baghdad’s daily bread while at the port city of Basra in southern Mesopotamia tidal-flow-powered mills did the same. At Basra water-powered mills also processed sugarcane, first crushing the cane and extracting its juice, which was then boiled down to produce refined, crystalline sugar. Other waterwheels powered big trip-hammers used by fullers to prepare woolen cloth and to pound vegetable fibers in water until it formed a pulp from which paper could be manufactured.
Paper production methods had come to the Islamic world serendipitously through the capture of Chinese prisoners skilled in papermaking during the victorious 751 battle of the Talas River in central Asia. These prisoners set up a workshop in Samarkand. From there papermaking technology later was transferred to Baghdad. In China the bark of the mulberry tree had long been used as the basic raw material. Lacking mulberries, rags, especially linen, were substituted in the Islamic world. The original manual production process was in two steps, with water playing a key role in both. First, torn-up rags were soaked, shredded, and beaten in vats with spiked clubs to produce a pulp—a manual process subsequently automated by pulp beaters powered by water. Next, the pulp was put in a vat of warm water, stirred, and strained through a molded wire latticework to produce rectangular sheets. The sheets were squeezed and hung dry, then rubbed as smooth as possible with stones, and finally immersed in a vat of gelatin and alum for stiffening. Baghdad’s water-powered paper pulp mill process spread west to Spain, and from there to Christian Europe a century later.
Paper manufacturing played a catalytic role in diffusing knowledge rapidly through the wide availability of books. Baghdad, for instance, had over a hundred bookshops by 900. Books helped usher in a glorious era of humanist enlightenment in the sciences, arts, philosophy, and mathematics, along with economic prosperity, and relative tolerance and peace. Greek, Persian, and Sanskrit manuscripts systematically were translated into Arabic from the early ninth century at Baghdad’s “House of Wisdom” created by Caliph al-Mamun. Ultimately, it would be through Islamic scholars centered in Cordoba—not the long-lived though decaying civilization of Constantinople and the Byzantine Empire—that Christian Europe beca
me reacquainted with the works of Aristotle and its own classical Greek intellectual heritage. This rediscovery later flowered as the European Renaissance to help give birth to postmedieval Western civilization. Muslim scholars made many original discoveries that also migrated to Europe. Algebra, trigonometry’s sine and tangent, the astrolabe and other navigational and geographical measuring instruments, the distillation of alcohol, and numerous medical treatments were among the most notable. Islamic alchemy contributed greatly to the development of the West’s scientific knowledge and methods. Islamic instrument makers even were working on elaborate gear trains for water clocks to be driven by waterwheels in the same period that China was employing this technology. A distinguished tradition of thinkers, among the best known of whom were Avicenna and Averroës, influenced mainstream Western philosophical development.
Yet sometime toward the end of the twelfth century—some historians use the death of Averroës in 1198 as the benchmark date—Islam’s most glorious era abruptly began to stagnate. Why the intellectual vitality and material growth suddenly drained away, and why its culture soon was eclipsed by more vigorous civilizations, remains one of the puzzling questions of history.
Steven Solomon Page 16
