Water: The Epic Struggle for Wealth, Power, and Civilization - Steven Solomon (2010)

Part I. Water in Ancient History

Chapter 6. Islam, Deserts, and the Destiny of History’s Most Water-Fragile Civilization

Golden age China overlapped and exchanged goods with a young, trading-based civilization that had emerged improbably out of the sparsely populated, parched desert of the Arabian Peninsula under the inspirational organizing banner of a new religion, Islam. During Islam’s brilliant flowering from the ninth through twelfth centuries, its civilization held sway over an extensive domain stretching from Spain in the west, across North Africa, south from Egypt along the East African coast to the Zambezi River near modern Mozambique, east from the Levant to the Indus River, and northeast in central Asia beyond the Oxus River to the western borders of the fabled Silk Roads. The riches underpinning its illustrious civilization came from its control of the Old World hub of long-distance land and sea trading routes linking the civilizations of the Far East, the Near East, the Mediterranean, and sub-Saharan Africa.

From its stunningly rapid rise to its puzzlingly abrupt fall from history’s center stage, the signature characteristics and historical destiny of Islamic civilization were overwhelmingly dictated by the challenges and responses to its scarce natural patrimony of freshwater. Islam’s core habitat was a desert surrounded by two saltwater frontiers, the Mediterranean Sea and the Indian Ocean. Precious few fresh hydraulic resources watered its interior. Its deserts contained scattered date-palm-shaded oases, underground springs and wells, and some seasonal wadis. Only a few large rivers—such as the Nile, the Tigris-Euphrates and to a much lesser degree the Jordan—were capable of sustaining intensive irrigated agriculture and the civilized, urban life that clustered around it. No navigable river or artificial waterway like China’s Grand Canal spanned the long distances of arid emptiness between water sources to unify and centralize the Islamic world’s political, economic, and social centers. Its noted dearth of small, perennial rivers—its so-called stream deficit—additionally made freshwater an omnipresent natural resource challenge for drinking, irrigation, transport, and waterpower that put great stress on the population-resource balances of Islamic society in all but a few privileged locations.

Islamic World & Selected Trade Routes

Constantinople

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Freshwater scarcity, in short, effectively rendered Islam a water-fragile civilization, extremely vulnerable to changes in natural and engineered hydrological conditions. As a result, its periods of abundance were temporary and its sufficiency rarely enduring. For centuries, the dearth of freshwater in its original Arabian habitat had been the primary obstacle confining its inhabitants to bare subsistence lifestyles. The Arab genius in transforming the obstacle of the hot, dry deserts, and subsequently the salty sea frontiers, into near-monopoly highways of trade was the key catalyst that launched Islam’s hallmark rise to greatness as a civilization controlling the long-distance movement and transit between East and West. Its precarious hydrological foundations also ultimately helped explain why its preeminence unraveled so quickly after the twelfth century.

Islamic civilization started with Muhammad, founding prophet of its monotheistic religion and revealer of the Koran, its holy book. Arabians at the time were polytheistic animists with strong tribal social structures. Many were still nomadic pastoralists, raising camels and raiding trade caravans. Settled life at the sporadic oases supported only very small populations. One important settlement, Mecca, was built around a spring with “bitter,” or salty, tasting water, and had only about 20,000 to 25,000 inhabitants. Mecca was located at an important restocking juncture for water and other supplies along the historic camel caravan trade route that carried frankincense, myrrh, and other luxuries between Yemen and the Mediterranean ports of the Levant. It was also specially advantaged because it was a regular destination of Arab pilgrims who came to venerate a black meteorite that had fallen nearby in antiquity and was regarded as divine.

Legend and Muhammad identified the origin of the Semitic Arabs as descendants of Ishmael, Abraham’s son by his maid-concubine, Hagar. From the beginning, water was always highly esteemed in both desert Arab and Islamic society. By tradition, no man or beast can be denied access to drink from a man’s well; the very transliteration of shari’aa, or Islam’s governing religious law, means “the way” or “path to the watering place.” Muhammad himself was born around 570 into a reputable but weaker clan of Mecca’s leading Quraysh tribe. Many Quraysh were merchants who had leveraged the power from the tribe’s control of water rights for the pilgrimage into lucrative participation in the camel caravan trade. Orphaned at a young age, the uneducated Muhammad grew up in the caravan trading business of his uncle and clan elder, Abu-Talib. Historians believe he traveled outside Arabia along the trade routes, where he encountered many new ideas and religions. At age twenty-five, he married a rich older widow with caravan business interests.

Everything was quite unexceptional about the life of Muhammad until about the age of forty. Then one night, in 610, while sleeping in a cave outside of Mecca, he had a supernatural experience. He had a vision of the Archangel Gabriel summoning him to be God’s chosen emissary and to begin reciting the first part of His revelation. For much of the next decade, Muhammad preached to a small group of followers, asserting that he was the final prophet in a line of divinely inspired Jewish and Christian messengers from Abraham, Moses, and Jesus. Islam meant simply a “submission” to God in all facets of life. As his following grew, the leading families of the Quraysh tried to suppress him. Muhammad’s position in Mecca became untenable when his uncle and tribal protector died in 619. Some of his adherents fled for Christian Ethiopia. In 622, Muhammad and a group of followers left Mecca for a settlement 200 miles north at the crowded, sweet water oasis of Yathrib, later renamed Medina, or “city of the prophet,” where he’d been invited to arbitrate disputes between local tribes.

From Medina, Muhammad’s power base grew rapidly. He expelled Medina’s Jewish tribes when they refused to acknowledge him as the true prophet. To supplement the limited agricultural resources of the oasis, he led his followers to raid camel caravans from Mecca in an expanding alliance with converted Bedouins, who shared profitably in the stolen booty. Before long, Muhammad was engaged in armed struggle with the Quraysh, possibly over control of trade routes. Several victories reinforced the religious fervor of the Muslim faithful that God was on their side, and gradually convinced Meccan leaders to negotiate the peaceful submission of Mecca to Islam by 630. As Mecca’s new leader, Muhammad abolished all blood and property privileges except custodianship of the cube-shaped Ka’bah shrine housing the black meteorite. Mecca replaced Jerusalem as the holy focal point of Muslim prayers.

Through control of the oases, marketplaces, and key caravan and trade routes, plus diplomacy backed by several military offensives, Muhammad rapidly united most of the tribes of the Arabian Peninsula under the banner of Islam. Yet when Muhammad died in 632 many of the tribal chiefs considered their oaths to Islam no longer binding and rebelled against the financial tribute Medina exacted from them. The first caliph, or “successor” to Muhammad, Abu Bakr, responded by organizing a regular army to quell the rebellions. The momentum of these military successes launched a growing Islamic fighting force of fierce nomadic tribesmen who soon reached the frontiers of Arabia’s great neighboring empires, Byzantine Rome and Sassanian Persia.

Under the ambitious and strong-willed second caliph, Omar, Arab armies surged across these frontiers and unleashed one of world history’s astonishing military juggernauts. Long-standing borders were swept away with stunning speed and world history’s cultural map was permanently transformed by seeding Islam throughout the conquered territory. One of the earliest and greatest victories was the August 636 battle of the Yarmuk River, a tributary of the Jordan River at the modern border of Syria, Jordan, and Israel. Aided by a dust storm that concealed their approach and fired by the zeal of religion and the lavish booty of imperial conquest, a large Arab army decimated a huge Byzantine force that became trapped with its back to the river, which soon ran bloody with its dead. By 642 Islamic armies controlled all of Syria and Palestine as well as Egypt’s Nile Valley—thus severing Byzantine Constantinople from two of its richest provinces. Other Arab armies meanwhile thrust eastward, seizing Mesopotamia and the wealth of its twin rivers by 641. By 651 the entire Sassanian Persian Empire had succumbed with astonishing ease. The historic border between Rome and Near East empires, stable for some 700 years, was obliterated in just fifteen years.

Historians have offered various explanations for the spectacular and improbable success of the small, modestly equipped Islamic armies against the huge Persian and Byzantine empires. Although both maintained the façade of imperial power, the two old empires had become internally enfeebled by wars, disease, political struggles, barbarian invasions, and economic corrosion from their failure to maintain agricultural water management infrastructure. In Persia, internecine political quarrels had weakened the central administration, which also failed to maintain the river-fed irrigation systems on the Tigris and Euphrates that had supported the original rise of its power. The resulting fall in crop yields undermined the society’s cohesion. The Byzantine grip on Egypt had been weakened by a century of low Nile floods during which land under cultivation had shrunk by half. The consequent famine, and an overlapping plague, had diminished Egypt’s population by the time of the Arab invasions in 639 to merely 2.5 million—half its Pharaohic height. The highly organized, religiously inspired Arab armies also created their own advantages, notably by the use of camel transport which helped them attack effectively over wide areas. In a typical battle, camels provided the supply trains until preparations were ready for horses, mounted by sword-brandishing cavalry, to make the final charge.

Islam’s military expansion continued, albeit at a less prodigious pace, following a power struggle and civil war that ended with the assassination in 661 of the fourth caliph, Ali. This was a seismic event in Islamic history. Islam’s ruling caliphate moved from Medina to Damascus, under the hereditary control until AD 750 of the Quraysh’s powerful Umayya clan. Moreover, Ali had been Muhammad’s cousin and husband of his daughter, Fatima. His demise ignited the bloody schism between establishment Sunni and dissident Sh’ia, who believe that legitimate leaders of Islam should descend only from the prophet’s direct household.

Under the Umayyads, North Africa was slowly brought into the Islamic fold. Aided by its new Berber allies—and in ships loaned by the Christian Byzantine Empire—Islamic soldiers crossed the Strait of Gibraltar to easily overthrow in 711 the Catholic Visigothic kingdom in Spain. The western Mediterranean, dominated by Rome in its heyday, was transformed into a Muslim lake. Arab fleets also became a force to be reckoned with in the waters east of Sicily and Malta. On land, raiders skirmished with Europeans deep into northern France over the next quarter century. In the east, Muslim armies crossed the Hindu Kush Mountains and stormed the Indus Valley between 708 and 711. The Caucasus mountains and the rich Oxus valley became the northeast borders of Islam’s empire following a Muslim defeat at the hands of Turkish steppe tribe warriors—many of whom were later converted to Islam—and a Muslim victory over a T’ang Chinese army at the Talas River in 751, an event which effectively closed the overland Silk Roads and diverted its trade to the Indian Ocean. Islamic armies also marched south along the African coast. By ejecting the Abyssinian Christians from the narrow Strait of Aden (the modern Bab-el Mandab), they took control of its tolls and opened up the entire Indian Ocean to Arab shipping. Large Arabian dhows were soon sailing the Indian Ocean’s two-way, seasonal monsoons and currents as far as Malacca and China and back again, and displacing Hindu shipping throughout the Old World’s richest long-distance-trading ocean.

By AD 750 Islam’s empire effectively had attained its largest geographical reach. It was a far-flung and decentralized empire with several competing regional centers and political interests loosely unified by a common religion, a common Arabic language, and enormous wealth derived from an extensive land and sea trading market economy. By one estimate the caliphate’s revenue was no less than five times greater than the Byzantine Empire’s by 820.

It was Islamic civilization’s meager freshwater patrimony for farming that compelled it to pursue its livelihood through trade and commerce by exploiting its occupancy of the lands at the crossroads of the civilized Old World. Its agriculture was confined to three main types of cultivation and habitats. Along the sandy coastlines where annual rainfall exceeded seven inches the olive tree provided nourishment, cooking oil, and lighting fuel. Around the scorching desert oases with temperatures of at least 61º Fahrenheit flowered the remarkably useful date palm with its eatable fruit, fibrous leaves for weaving, and trunk for scarce wood. Only in the few irrigable river valleys, or on plains where more than 16 inches of rain fell each year, could the basic grains for Islam’s daily bread be cultivated. In between the expanses separating these agricultural pockets roamed small clans of nomadic, seasonal groundwater and grass-seeking desert pastoralists who bred camels and other animals that provided the milk, meat, clothing, and tent skin mainstays of their simple, subsistence lifestyles.

Freshwater scarcity thus profoundly shaped the nature, institutions, and history of Islamic society. Water imposed constraints on food production and set limits on the maximum size of Islam’s sustainable population. For instance, in its halcyon days, Islam could support only 30 to 50 million people; at the time, China’s population was triple that number and world population was ten times greater. As a result, Islam was a civilization that chronically lacked manpower and was forced to expand through religious conversion and conquest. Islam’s religious universalism and Arab leaders’ eventual acceptance of non-Arab converts were likewise shaped by this demographic shortfall. So was the unusual degree of tolerance with which conquered peoples, mercenaries, and even its large slave population were absorbed into its society.

Freshwater scarcity also forced Islam’s population to be highly concentrated around each region’s few good water sources. Overcrowded towns of exceptional size and a few cities of dazzling, world-class accomplishments, such as Baghdad, Cairo, and Cordoba, were characteristic of Islamic society. Typically, a grand mosque surrounded by commercial markets lay at each town center, which was encircled by a web of twisty, narrow, and unsanitary streets built on slopes from which the rare rains would wash away the refuse.

At the height of its glory, three disparate, rival regional power centers arose—Spain-Magrib, Egypt-Levant, and Mesopotamia-Persia—reflecting and magnifying the religious and tribal divisions within Islam. In such decentralized circumstances, economic organization by command was impossible. Instead, it was the invisible hand of market forces that governed the signature transit and trade that held together Islam’s economy and helped stimulate the breakthroughs underpinning its civilization’s rise. “Not being well endowed by nature,” observes historian Fernand Braudel, “Islam would have counted for little without the roads across its desert: they held it together and gave it life. Trade-routes were its wealth, its raison d’être, its civilization. For centuries, they gave it a dominant position.”

Water scarcity presented the primary obstacle standing between Islam and its historic rise to greatness through trade. First and foremost, it needed a way to cross the long expanse of its own hot, waterless interior deserts. Its first triumphant innovation, which at a stroke transformed the barren desert barrier into an insulated, exclusive Islamic trade highway, came by its disciplined organization of the hardy camel, with its prodigious water-storing capacity, into long trade caravans and military supply transports. A caravan of 5,000 to 6,000 camels could carry as much cargo as a very large European merchant sailing ship or a fleet of barges on China’s Grand Canal. Islam’s quasi-monopoly over this powerful pack animal provided it with the mobility to cross and exit its desert homelands—and to make its mark on world history.

The one-humped Saharan dromedary was specially adapted for the hot deserts. It could go without drinking water for a week or more, while plodding some 35 miles per day across the desert sands with a 200-pound load on its back. Water was stored in its bloodstream—its fatty hump, which grew flaccid during long journeys without nourishment, functioned as a food reserve—and it maximized water retention by recapturing some exhaled water through its nose. Once at a water source the camel speedily rehydrated by consuming up to 25 gallons in only ten minutes. It even could tolerate briney water. It possessed an uncanny memory for the location of water holes. Moreover, it could eat the thorny plants and dry grasses that grew on arid lands and were indigestible by most other animals. During a trip, camels could lose one-quarter their body weight, twice the amount fatal to most other mammals. The camel’s extraordinary physical attributes made it possible for caravans to make the two-month, trans-Sahara trip from Morocco to Walata at the frontiers of the Mali Empire in Africa, which included one notorious stage of ten waterless days.

Like seas, deserts have played a distinctive role in history as expansive, empty spaces between distant civilizations. Initially, both imposed formidable geographic barriers of separation. But when traversed by some transport innovation, they were rapidly transformed into history’s great highways of invasion, expansion, and cultural exchange that often abruptly realigned regional and world orders. Camels took Arab merchants and soldiers everywhere. Ultimately they reached Islam’s other great water challenge—the frontier of its seashores. Islam’s second water breakthrough was to extend its overland desert trade franchise to mercantile mastery of the Old World’s great sea waterways, the Indian Ocean and much of the Mediterranean Sea. Its large dhows, their hulls made of planks tied together with date palm or coconut tree fibers and propelled by triangular lateen sails, which were highly maneuverable against headwinds, and steered with nimble stern rudders, became the caravans of the seas that carried Sinbad the Sailor on the adventures described in the classic literary cycle The Thousand and One Nights.

The long-distance trade route from the Moluccas or Spice Islands of Indonesia across the Indian Ocean to India and the West became in Muslim times the single greatest highway to world power and empire. At a time before Europeans had unlocked the secret arts of sailing across the open oceans and discovered the riches of the New World, and when the Silk Roads were closed, Arab dhows carried the lion’s share of the world’s most desirable goods and spread Islamic civilization throughout the richest coastal ports of call in the world.

Thanks to the Indian Ocean’s unique, seasonally reversing wind system, Arab seamen could set out with a full load of goods between April and June by following the southwesterly monsoons, arrive within two months, do their trading, and fill up their cargo holds with profitable Oriental luxuries in time to catch the reliable fair winds from the northwest that would carry them home when cooling meteorological conditions reversed the monsoon’s direction in winter. Arab vessels also plied the Mediterranean Sea from Spain to Alexandria and the Levant. Compared to the Indian Ocean, however, the Mediterranean’s seaports offered far less alluring wealth while its unidirectional west-to-east winds made sailing more difficult.

By integrating its command over the resources of two disparate water environments—the waterless desert and the salty sea—Islam’s influence soared. Camels and dhows defined its seamless land and sea caravan network that could transport goods and people between the four corners of the Old World. Disassembled dhows were transported by camel across the Sahara Desert for assembly and launch, camels and all, across the Red Sea. Once on the Arabian Peninsula, the ships were again disassembled and portaged for the long, landward rest of the journey along the wadis and oases to the ports of the Arabian Sea that led to the Indian Ocean. The preference for this laborious overland route was that for centuries the rocks and coral reefs, unpredictable winds, irregular currents, and pirate-infested waters of the deep, salty Red Sea were more perilous to navigate than the great deserts along its coasts. Many of the seaways and coastlines leading to the Indian Ocean’s fabulously rich sea-lanes also were inhospitable and dangerous for seafaring. Arabia’s absence of navigable rivers and its scant number of good harbors with sufficient freshwater made supplying ships extremely difficult; the lack of wood resources in the arid landscape was a second, water-related impediment. Adding to the navigational problems for seamen, the Arabian coast was notoriously stormy.

Islamic merchants nevertheless overcame these water obstacles. In Mesopotamia goods went by river to Baghdad, then overland west to Syria and Egypt, north to Constantinople and Trebizond on the Black Sea, and east through northeastern Iran and thence to central Asia and China. Gold and slaves from Sudan, Oriental silk, peppers, spices and pearls, and much of everything else transited through Islamic lands by Arab traders. After about 1000, European vessels from the Republic of Venice and other rising small sea states increasingly handled the final transshipments from Alexandria and other Arab ports throughout the Mediterranean in commercial alliances that often transcended religious rivalries.

Islam’s expansive economic power made it a great military force that encroached upon and threatened neighboring civilizations. The native sub-Saharan civilizations of the Niger River fell under domination by Muslim states following the conquest of Ghana in 1076. Much of East Africa, with the notable exception of the Abyssinian highlands of modern Ethiopia, also succumbed. In India, Hindu civilization was in retreat from Islamic conquests over hundreds of years through the seventeenth century. Europe, too, barely survived the onslaught of Islam’s initial military juggernaut from 632 to 718, and remained at peril for several centuries in the heated clash of civilizations that continued in earnest across the Mediterranean throughout the sixteenth century.

Christianity, and all that later flowered into Western civilization, came closest to possible extinction in the year from AD August 717 to August 718. During those 12 months, a huge Muslim naval and army force of over 2,000 ships and 200,000 men laid siege to Constantinople, seat of the Byzantine Empire, inheritor of Rome’s civilization, and Christendom’s greatest city. Had the imperial city, located on the strategic triangular promontory overlooking the junction of the Bosporus Strait and the Sea of Marmara that controlled the narrow 225-mile waterway linking the Mediterranean and Black Sea trade routes and divided Europe from Asia, fallen under Islam’s flag, the entire Mediterranean Sea likely would have become a Muslim lake. Europe’s interior, via the river Danube and toward the Rhine, would have been wide open for an easy Muslim march of conquest. Europe, and the entire Western world, today might be Muslim. In the event, the siege of Constantinople would be an epic turning point in the clash of civilizations between Islam and the West. It was also a dramatic illustration of the geostrategic advantage of a strong water defense.

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 from 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 became 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.

The most traumatic symbol of Islamic civilization’s decline was the devastating Mongol sack of Baghdad on February 20, 1258. Mounted Mongol warriors, using gunpowder-fired weapons in their relentless surge of conquest across the Eurasian steppes from China to the Near East to the doorstep of central Europe, stormed the once-illustrious city to loot, burn, pillage, and slaughter. In customary Mongol fashion, hundreds of thousands of residents were massacred. The last caliph, in a calculated symbolic act of contempt, was trampled to death under the hoof of a Mongol horse. The obliteration of the Abbasid capital was completed by the destruction of many surrounding irrigation dikes and waterworks to render impossible any agricultural resurrection. It was the first time that non-Muslim invaders had been able to impose infidel rule in the Islamic heartland. Christian Europe was spared a similar agonizing fate as that experienced at the hand of the Mongols by both Islam and China only due to a fluke of history. News of the death of Genghis’s son and successor, Ogadei, had reached the banks of the Elbe River during the 1241 conquests when Europe lay prone for the taking. Mongol commanders, uncertain how the power vacuum in Karakorum would be filled, voluntarily pulled back their forces into Russia. Eventually they invaded other regions, and looked beyond the relatively meager wealth of medieval Europe for richer prizes.

Yet Islamic civilization had been in critical decline long before the arrival of the vanquishing Mongol cavalry. Like the Persian and Byzantine empires overrun by the first Arab armies of the seventh century, the foundation of its economic prosperity had grown internally stagnant. A principal cause was faltering water management and its inability to keep technologically ahead of its inherent scarcity of freshwater resources. The agricultural productivity of Mesopotamia, for instance, deteriorated markedly with the rising political influence of Islam’s nomadic converts who increasingly supplied the Arab caliphate’s military manpower. Most notable of these were the Turks, who held effective power in Baghdad after 1055 under the nominal leadership of the Abbasids. Dependency on the Turks was a consequence of the limitation water scarcity had imposed on the size of the ruling native Arab population. While the Abbasid dynasty’s founders had arduously rebuilt and maintained irrigation waterworks on the Tigris-Euphrates and Nahrwan canal system and had expanded cultivated cropland to its largest extent into the eleventh century, the recently nomadic Turks were steeped in the traditions of steppe herders who followed their sheep and horses between water holes and seasonal grasslands. Under Turkish influence, centralized political authority waned and Mesopotamia’s irrigation system eroded. Inadequate maintenance caused irrigation and drainage canals to clog with silt. Soils became waterlogged and deadly salt rose to the surface of the floodplains between the twin rivers. As in ancient times, salt-whitened fields produced falling agricultural yields and declining population levels.

Deteriorating irrigation maintenance also helped cause both the Euphrates and the Tigris to make major disruptive course shifts around the year 1200. The Tigris’s return to its former, more easterly channel north of Baghdad was a twin disaster because not only did this realignment dry up a large tract of irrigated cropland, but it also destroyed part of the 400-foot-wide Nahrwan transport and irrigation canal and the agricultural network it supported downstream. The agricultural decline in Mesopotamia coincided with a parallel shrinkage and collapse by the twelfth century of irrigation in Egypt. Thus both of the Islamic world’s great breadbaskets fell into crisis at the same time. As always, the level of Nile floods was the key determinant of Egyptian prosperity and the political system that depended upon it. Ample Nile floods had buttressed the first three centuries of Arab rule. A period of low Nile floods between 945 and 977, however, eroded the amount of land under cultivation and paved the way for the conquest of Egypt by the Shiite Fatimids in 969. Fatimid rule was eventually undermined by two generations of low Nile floods that produced cannibalism, plague, and decaying waterworks. In 1200 one-third of Cairo’s population perished from severe famine when disastrous low floods returned after a long period of normality. This catastrophe fueled the enduring Egyptian suspicion that the upriver emperors of Ethiopia somehow had made good on their threat to divert the Nile’s waters. By the time the Mamluks, white Muslim slave soldiers of ethnic Turkish origins, seized power in Egypt in 1252, irrigated agriculture had fallen into such desuetude that the Nile breadbasket was able to support no greater population than the one Arab conquerors had inherited from the Byzantines in the seventh century. The revival of Nile irrigation awaited the water engineering projects of the Turkish and British overlords in the nineteenth and twentieth centuries.

In Muslim Spain the problem was less one of waterworks deterioration than of a failure to innovate to find more efficient ways to exploit their existing water resources. When the Christian Europeans reconquered Spain, they inherited an extensive irrigation network with highly developed social and administrative processes—including the famous water court at Valencia, the oldest democratic institution in Europe, whose elected judges have adjudicated irrigation disputes in public for over a millennium. But it was entirely based on Middle Eastern traditions of small-scale river diversion dams for irrigation, water-power, and water supply. Muslim engineers had ample familiarity with large impoundment dams and aqueducts used in Spain by the ancient Romans. But they never experimented with them in order to improve their water use productivity. Their Christian successors did. Their successful innovations helped Spain flourish after 1492 when the armies of King Ferdinand and Queen Isabella expelled the last Moors from the Iberian Peninsula.

Photographic Insert

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Lifting, damming, and channeling water has often made the difference between agricultural surplus and famine. Water-lifting irrigation devices, such as the workhorse Middle Eastern noria or chain of pots (1) and Archimedes’ screw (2), have remained in continuous use since antiquity. Handbuilt, water-storage earthen dams, like the one being reinforced by rural Kenyan villagers in 2004 (3), were mainstays of Egyptian and Mesopotamian hydraulic civilizations five millennia ago.

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Wet rice farming requires intensive and sophisticated water management. Nineteenth-century Chinese farmers sow rice and move water on wooden treadle pumps according to traditional methods.

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A highland Ethiopian farmer in 2008 plows his field in a manner virtually unchanged since the start of civilization.

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Two notable vessels of the seafaring Mediterranean world were the ancient Greek’s nimble warship circa 480 BC, the trireme (6), with its deadly pointed ram at the bow, and the lumbering Roman cargo ship circa AD 200 (7) that transported goods from the far reaches of the empire to feed the enormous imperial capital.

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Marcus Agrippa (8), Augustus’ lifelong right-hand man, transformed the empire’s health, military robustness, and civic society by institutionalizing the public supply of abundant, clean water through extensive aqueducts, such as the remnant at the Pont du Gard in southern France (9), to urban fountains, baths, and functioning sewers.

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Li Bing built sophisticated waterworks, like the still-functioning Min River diversion weirs in Sichuan, that spread prosperity and helped the Ch’in dynasty consolidate power throughout China in the third century BC.

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The completion of the 1,100 mile Grand Canal (11) in the seventh century AD united the resources of the south’s Yangtze and the north’s Yellow River and catalyzed China’s spectacularly advanced medieval civilization. The New Grand Canal in the early fifteenth century signaled the nation’s fateful turn inward and voluntary withdrawal of its indomitable fleets from the high seas. A traditional seagoing Chinese junk (12).

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Islam’s glorious age, from the eighth to twelfth centuries, was built upon a vast trading network of desert-crossing camel caravans (13) and lateen sail-rigged, cargo-carrying dhows (14), which spanned from Atlantic Spain across the Indian Ocean and south along Africa’s coasts and interior river civilizations. Yet Islam’s arid homeland’s shortage of small rivers limited its use of waterwheels for power and irrigation, like the one functioning on the Orontes River at Hama, Syria (15), in the early twentieth century, and contributed to its rapid decline from world prominence after the twelfth century.

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The heavy moldboard plow, widespread in northwestern Europe by the tenth century, was one of the seminal innovations of the region’s agricultural revolution and belated economic rise.

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Northern Europe’s many navigable and fastrunning rivers became arteries of commerce and production. Waterwheel-powered bread flour gristmills, like this old wooden waterwheel mill in northwestern France, were ubiquitous.

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Water power was applied most notably to medieval industrial production, including rolling iron, as shown at this 1734 Swedish mill, and to drive huge leather bellows to heat furnaces for high-volume iron casting.

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Europe’s world dominance began after 1500 with the advent of transoceanic sailing and long-range naval cannonry, which followed the Voyages of Discovery championed by Portugal’s Prince Henry the Navigator. Vasco da Gama (19) sailed around Africa’s cape to India, and Columbus crossed the Atlantic to the New World, with the help of the discovery ship par excellence, the caravel (20).

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The apogee of naval power in the age of sail was achieved by England, whose two greatest admirals, Francis Drake and Horatio Nelson (21), helped defeat the Spanish Armada and Napoléon, respectively. A 120-cannon French warship (22) from the Nelson-Napoléonic era.

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In 1763, James Watt (23) began repairing this model of Newcomen’s early steam engine (24). The result was the modern steam engine, the seminal invention of the Industrial Revolution.

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Powerful steam engines, like Watt’s rotary motion 1797 model, superseded waterwheels to drive the world’s great early automated factories and iron mills that underpinned the world dominance of the nineteenth-century British empire.

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Robert Fulton’s (27) Clermont (26) on New York’s Hudson River ushered in the age of river steamboats. Fulton’s vigorous advocacy for American canals also helped spur the development of the Erie Canal.

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Forsaken in love, the Duke of Bridgewater focused his energies on pioneering the building of a canal in 1761 from his coal mine to Manchester. His success ignited a national canal-building boom that transformed England’s economy.

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America’s visionary canal builder was New York’s De Witt Clinton (29), who celebrated the 1825 completion of the Erie Canal with a ceremonial wedding of the Lake Erie’s water with the Atlantic Ocean at the Hudson River’s mouth. By providing an economical east-west route across the Appalachian Mountains, the 363-mile-long Erie Canal (30) transformed America’s destiny by linking New York and the eastern seaboard to the Mississippi Valley and the vast resources of the continental interior.

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The arrival of abundant, clean freshwater from a new aqueduct network in upstate Croton in 1842 relieved celebratory New Yorkers of their chronic water scarcity and affliction by waterborne diseases.

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English leader Benjamin Disraeli championed the sanitary reforms that triggered the industrial world’s public health revolution. Disraeli later seized the opportunity that enabled England to gain influence over the vitally strategic Suez Canal, which linked the Mediterranean to the Red Sea and the Indian Ocean.

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The entrepreneurial genius behind the 1869 Suez Canal was French Viscount Ferdinand de Lesseps. De Lesseps’ later effort to build an interoceanic canal between the Atlantic and Pacific Oceans failed, but galvanized events that ultimately led to the creation of the Panama Canal.

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The driving force behind the Panama Canal was America’s greatest water president, Teddy Roosevelt (35), who got behind the controls of huge steam shovel (34) during his heralded visit to the canal zone to make good on his promise to make “the dirt fly.” The first steamer sailed through the canal’s famous Culebra Cut in August 1914 (36).

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Dust storms, like the one of April 14, 1935, approaching Rollo, Kansas, and created partly by man’s mismanagement of a fragile water environment, ravaged the plains during the Great Depression. Pumping water accumulated over eons in huge, deep underground aquifers soon transformed the Great Plains into one of world history’s great breadbaskets, but raised doubts about its long-term sustainability.

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“I came, I saw, I was conquered . . .” President Franklin Roosevelt’s September 30, 1935, dedication (38) of the Boulder (later renamed Hoover) Dam (39) inaugurated one of the great eras of water history. Giant, multipurpose dams transformed America’s arid Far West, helped the country win World War II, and spread the worldwide Green Revolution.

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Egyptian President Gamal Abdel Nasser was adulated by Arabs throughout the Middle East. He triggered a crisis with the great Western powers when he nationalized the Suez Canal in 1956 and contracted with the Soviet Union to construct the multipurpose high dam on the Nile at Aswan, a project he likened to the great pyramids.

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Like great dynastic founders throughout Chinese history, Mao Zedong launched massive development waterworks to reengineer China. Today, the nation has nearly half the world’s 45,000 large dams, including the controversial super giant at Three Gorges on the Yangtze, and a continentalscale south-to-north river water diversion scheme.

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Water development has come much more slowly for two poor rural Kenyan villagers, who in 2004 laid a two-mile-long water pipe that finally brought clean, fresh water to their village from a rural well after a thirty-year wait.

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Rachel Carson’s (43) Silent Spring, highlighting the extensive toxic pollution of waterways, was one of the seminal birth moments of the modern environmental movement. Congress was finally galvanized to enact comprehensive clean water regulations after Cleveland’s filthy Cuyahoga River, seen burning in 1952 with industrial pollution (44), again burst into spectacular flames in June 1969.

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Climate change, energy, and food issues are intimately interconnected with water. Retreating mountain glaciers from global warming, such as those that sustain Asia’s great rivers and a fourth of humanity, threaten catastrophic droughts and hydroelectricity shortages in the dry season and devastating floods during the monsoons.

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One fifth of humanity still lacks access to enough clean, fresh water for basic domestic needs and two-fifths for adequate sanitation, compelling hundreds of millions, especially children (46) and women, to forgo education and productive work to walk several miles each day to fetch water for daily survival. Billions in poor regions with inadequate water infrastructure, like Ethiopia’s highlands near Lake Tana (47) at the source of the Blue Nile, try to endure water’s natural destructive excesses, such as floods, mudslides, and droughts.

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With freshwater use increasing twice as fast as soaring world population growth, a perilous new planetary era of water scarcity is dividing global society and politics between fresh-water Haves and Have-Nots, and establishing a fifth, vital historical use for water—to sustain the earth’s lifegiving water ecosystems.

Another major water fragility that undermined Islamic civilization was its shortage of small rivers. Islam’s “stream deficit” not only inhibited its development of a speedy, safe, and extensive internal transport network. It also handicapped Islam in exploiting one of the rising sources of potential competitive advantage during the Middle Ages—waterpower. Although Muslim hydraulic engineering knowledge was more advanced than in Europe, the waterwheel never played as important a role simply because of its natural shortage of fast-flowing streams. At a time when rival Europe was learning to apply the abundant waterpower and transport potential of its many small rivers to the development of the early industry that helped drive its historical ascendancy, Islamic Spain continued to use the waterwheel almost exclusively for grinding grain and lifting water. The use of energy derived from waterpower was a seminal factor in the development of early industry. By the mid-twelfth century, Europeans had already attained parity with Islam in waterpower.

Islam’s inability to maintain its early command of the high seas was also another key factor in its rapid decline after the twelfth century. In hindsight, the first mortal blow was its failure to defeat Constantinople in 718 and thus monopolize the Mediterranean as an Islamic Lake. This left the door open for European maritime states to build up their sea power. By the late eleventh century, they began to take over the key trade routes. Gradual expulsion from Mediterranean sea trade eliminated a major source of wealth and forced Islamic civilization to rely more extensively on its water-scarce, desert resources and propelled the abruptness of Islam’s reversal of fortune.

Yet Islam also failed to fully consolidate its greatest opportunity of all—its control of the rich, long-distance Indian Ocean trade. In the Indian Ocean, the Muslims proved to be timid, shore-hugging sailors. They ventured into the open seas only when absolutely necessary. Nor were they intrepid explorers of the unknown. In Africa they traveled south as far as the treacherous Mozambique Channel between the mainland and the large island of Madagascar, but no farther. Ironically, the channel became known in Arab history as “the passage of the Franks” through which the Europeans—whom the Muslims called “Franks”—sailed when they transformed history by rounding the cape of south Africa and bursting into the Indian Ocean at the end of the fifteenth century. Why Muslim seamen already preeminent in those waters did not try to push on around the African cape into the Atlantic long before Europeans made the breakthrough voyage in the opposite direction may appear in hindsight to be one of world history’s great missed strategic opportunities. Yet, in fact, it was simple enough to understand. They had little economic incentive to do so—they already controlled the most profitable trade routes in the world.

Islam’s decline at sea more broadly was due to its failure to transform itself into a true maritime civilization. While it occupied the second frontier of its seas, it never genuinely absorbed it into a dynamic new synthesis with its original desert-borne civilization. Alexandria, despite all the advantages of its wonderful large harbor and its central location at the trade interstices of the Mediterranean and routes east, never became a Muslim Venice. Islam coped with its deficit of streams, good harbors, and dangerous coastlines, but it did not truly overcome it. Culturally, Islam remained fundamentally land-oriented. It thus left itself vulnerable to being outflanked when Christian infidels mounted their great challenge to Islam at sea.

One recurrent lesson of history is that societies that passively live too long off old water engineering accomplishments are routinely overtaken by states and civilizations that find innovative ways to exploit water’s ever-evolving balance of challenges and opportunities. Thus Muslims failed to meet the challenges posed, first by Chinese junks and then, after China’s voluntary withdrawal from the seas, by the spectacular entrance in early 1498 of the Portuguese explorer Vasco da Gama into the Indian Ocean. As often is the case in hindsight, one civilization seems to surpass another, as Muslims did in displacing the Byzantines and Persians, with startling abruptness because advantages have been quietly building up for some time and then express themselves with full force all at once. Advances in navigation, shipbuilding, and sea weaponry had been steadily expanding the opportunities for cheaper, quicker, and safer sea transport and trade. But the ascendancy of sea power was not awesomely displayed until the moment da Gama’s fleet rounded Africa’s cape and crossed the Indian Ocean and pulled into the port at Calicut, India. In little more than a decade, sturdy Portuguese ocean vessels, armed with cannons that had an effective range of 200 yards, seized control of the Muslims’ richest sea routes across the Indian Ocean to the Spice Islands. Portugal’s opening of the all-water spice route to India also broke the long-standing Venice-Alexandria stranglehold on the trade of oriental goods throughout the Mediterranean. Venetian overtures to Egypt’s rulers to reopen Pharaoh Neko’s old Red-Sea-to-Nile “Suez” canal route as a countermeasure came to nought. As a result, the traditional overland camel and sea caravan routes that had yielded so much of Islam’s wealth went into accelerated, lasting decline.

Sea power also emerged as the weakest link of Islam’s militant revival under the Turks from the fifteenth century. The Turks were originally Far Eastern nomadic steppe cousins of the Mongols. Between the ninth and eleventh centuries, many Turkish tribes entered Islamic territories in the Middle East and converted to Islam, often serving as mercenary soldiers. Over time they became the military backbone, and then the political masters, of Islam. When the era of Mongol hegemony ended, the Ottoman Turks embarked on a military expansion into the Anatolian highlands of modern Turkey.

In 1453, Turks under the command of the young Mehmet II, thereafter “the Conqueror,” sent a shudder through all European Christendom by finally taking Constantinople and making it their new capital. The final assault against the historic city was won with the help of a gigantic cannon built by a Hungarian engineer and by Mehmet’s own master stroke against the nearly impregnable Golden Horn. His forces dragged 70 galleys overland and launched them behind the Byzantine imperial squadron guarding the Horn’s entrance. For the next 200 years, the Turks spearheaded a new Islamic jihad against Christian Europe. In the sixteenth century formidable Turkish Islamic armies stormed through Greece, the Balkans, and Hungary and in 1529 laid siege to Vienna on the Danube in central Europe. During the peak of their power under Sultan Süleyman the Magnificent, who ruled from 1520 to 1566, even Rome itself felt threatened. As late as 1683 Turkish armies were capable of besieging Vienna a second time.

Europe had reacted to the first Arab-led Islamic expansion by launching the Crusades to retake the Holy Land; its response to the Turkish-led second clash of civilizations included a series of sea battles for control of the Mediterranean. Although the Turks’ new fleets had reestablished Muslim sea power and had captured the strategic eastern Mediterranean island of Cyprus in 1570–1571, the Turkmen were no match for European vessels, sailing skills, and naval tactics developed in rough gales and currents of the Atlantic Ocean. In 1541, Lufti Pasha, a former grand vizier to Süleyman, became concerned that while the Ottomans were powerful on land, they were vulnerable to their Christian enemies at sea. His assessment was proven correct in the climactic sea battle between the combined fleets of Christendom and the Turks on October 7, 1571, off the Greek coast at Lepanto, not far from the site of the Battle of Actium that had ended Rome’s civil wars. The bloody, four hour Battle of Lepanto is celebrated not just for signaling Christian Europe’s decisive triumph over resurgent Islam at sea, but also for marking a turning point in the history of naval warfare—it was the first major sea battle in which gunpowder was important. The Turkmen fought mainly the way most major sea battles had been fought since antiquity—they tried to re-create the conditions of a land battle aboard ship. Their soldiers were armed mainly with bows and arrows and swords for close combat; their pilots and oarsmen tried to ram their galleys into enemy vessels or maneuver them alongside close enough for grappling hooks to draw them together to permit boarding and hand-to-hand fighting. The Christian fleets, by contrast, fought with weapons that presaged the dawning new era of naval warfare. Their galleys had cannons mounted on their bows and their soldiers were armed with muskets or arquebuses that could fire at and hit the enemy from a distance. The Venetians also unveiled an entirely new class of warship, a galleass, that was much bigger than traditional galleys, with 50-foot oars manned by half a dozen men, and large swivel guns. History’s next great sea battle, the British defeat of the Spanish Armada seventeen years later in 1588, would complete the transformation to modern artillery-based sea warfare from a distance. At Lepanto, a total of 30,000 men died in the Christians’ bloody victory over Islam. Among the Christian wounded was Miguel Cervantes, the author of the novel Don Quixote,who through his life proudly displayed his maimed left hand as proof of his role in the battle. Lepanto crippled the expansionist ambitions of the Turkish Empire by curtailing its mobility at sea and its access to the vital resources that moved along the world’s sea-lanes.

The sea battle with Europe illustrated that Islam’s demise from international preeminence was only partly due to its own absolute response to its internal water resource fragilities. What its neighbors were doing with their water resources determined outcomes too. Civilizations’ responses to their water challenges throughout history were variable and always in flux. Some civilizations rose sooner because water conditions in their habitat were more favorable to being exploited by available technologies and forms of organization. Hydraulic civilizations, for instance, arose earliest because semiarid, flooding river valleys offered opportunities for irrigation they had the ready means to exploit. The development of Islam’s trade, using camels to carry goods through its harsher desert habitat, took much longer. Still other regions with even more inauspicious water resource endowments faced challenges so daunting as to all but relegate their native societies to subordinated starting positions in the ongoing competition among societies.

Such was the destiny of much of sub-Saharan Africa, where geography presented formidable hurdles. Its equatorial rain forest regions, like tropical lowlands everywhere, were ecologically precarious habitats particularly inimical to the development of large, advanced civilizations. Its soils were permanently saturated sponges, extremely difficult to clear for farming and unhealthy for human settlement. Travel was hard, except by river. Nonetheless, impressive civilizations did develop in the surrounding drier, more hospitable tropical forests and transitional savanna lands, such as the successive empires that flourished around the Niger River and the headwaters of the Senegal and Gambia rivers. But for a long time these civilizations developed in isolation behind the barrier of large deserts and the impenetrable ocean that limited their ability to engage on equal terms with other societies in the cultural and economic exchange that has stimulated civilization in every age. It was not surprising that the external barriers of sub-Saharan African empires were breeched first by neighboring civilizations propelled by superior competitive advantages in water technology—camel caravans by Arab traders and later by the oceangoing vessels of the Europeans. Following international history’s inexorable progression from trade to raid and domination, the Muslims and Europeans pressed their advantages by imposing exploitative relationships upon Africans through trade, conquest, and colonization. The ultimate symbol of this inequity was the large slave trade in black human beings. For centuries this was a monopoly of the Arabs. But when European ships appeared on the Atlantic coast of Africa and offered cheaper and safer sea routes, as well as new markets in the New World, domination of the slave trade shifted from the Arabs to the Europeans.

The Europeans on the ocean-bounded, cold, and wet northwestern edge of the civilized Old World had also inherited water resources that were extremely challenging to tap and harness. For millennia non-Mediterranean northern Europe remained an impoverished backwater. But when its inhabitants finally broke out of the ocean-bound confines of their peninsula-shaped continent with the innovation of open sea sailing, they gained command over one of the most dynamic water advantages in all world history. For much of previous history, sea power mainly had helped small states survive defensively against much larger land-based states with powerful armies; naval prowess equalized the balance of power by enlisting the formidable difficulty of navigating the sea itself into the battlefield, and by stretching and harassing enemy supply lines. But with the advent of open sea sailing, control of the oceanic highways of the entire world suddenly was transformed into an overwhelming offensive advantage. With China’s voluntary turn inward and propelled by their leadership at sea, Europeans were able to exert an extraordinary, global dominance that was to last half a millennium.