IN 1961, as a young academic, I called on President Harry S. Truman when I found myself in Kansas City delivering a speech. To the question of what in his presidency had made him most proud, Truman replied, “That we totally defeated our enemies and then brought them back to the community of nations. I would like to think that only America would have done this.” Conscious of America’s vast power, Truman took pride above all in its humane and democratic values. He wanted to be remembered not so much for America’s victories as for its conciliations.

All of Truman’s successors have followed some version of this narrative and have taken pride in similar attributes of the American experience. And for most of this period, the community of nations that they aimed to uphold reflected an American consensus—an inexorably expanding cooperative order of states observing common rules and norms, embracing liberal economic systems, forswearing territorial conquest, respecting national sovereignty, and adopting participatory and democratic systems of governance. American presidents of both parties have continued to urge other governments, often with great vehemence and eloquence, to embrace the preservation and enhancement of human rights. In many instances, the defense of these values by the United States and its allies has ushered in important changes in the human condition.

Yet today this “rules-based” system faces challenges. The frequent exhortations for countries to “do their fair share,” play by “twenty-first-century rules,” or be “responsible stakeholders” in a common system reflect the fact that there is no shared definition of the system or understanding of what a “fair” contribution would be. Outside the Western world, regions that have played a minimal role in these rules’ original formulation question their validity in their present form and have made clear that they would work to modify them. Thus while “the international community” is invoked perhaps more insistently now than in any other era, it presents no clear or agreed set of goals, methods, or limits.

Our age is insistently, at times almost desperately, in pursuit of a concept of world order. Chaos threatens side by side with unprecedented interdependence: in the spread of weapons of mass destruction, the disintegration of states, the impact of environmental depredations, the persistence of genocidal practices, and the spread of new technologies threatening to drive conflict beyond human control or comprehension. New methods of accessing and communicating information unite regions as never before and project events globally—but in a manner that inhibits reflection, demanding of leaders that they register instantaneous reactions in a form expressible in slogans. Are we facing a period in which forces beyond the restraints of any order determine the future?

Varieties of World Order

No truly global “world order” has ever existed. What passes for order in our time was devised in Western Europe nearly four centuries ago, at a peace conference in the German region of Westphalia, conducted without the involvement or even the awareness of most other continents or civilizations. A century of sectarian conflict and political upheaval across Central Europe had culminated in the Thirty Years’ War of 1618–48—a conflagration in which political and religious disputes commingled, combatants resorted to “total war” against population centers, and nearly a quarter of the population of Central Europe died from combat, disease, or starvation. The exhausted participants met to define a set of arrangements that would stanch the bloodletting. Religious unity had fractured with the survival and spread of Protestantism; political diversity was inherent in the number of autonomous political units that had fought to a draw. So it was that in Europe the conditions of the contemporary world were approximated: a multiplicity of political units, none powerful enough to defeat all others, many adhering to contradictory philosophies and internal practices, in search of neutral rules to regulate their conduct and mitigate conflict.

The Westphalian peace reflected a practical accommodation to reality, not a unique moral insight. It relied on a system of independent states refraining from interference in each other’s domestic affairs and checking each other’s ambitions through a general equilibrium of power. No single claim to truth or universal rule had prevailed in Europe’s contests. Instead, each state was assigned the attribute of sovereign power over its territory. Each would acknowledge the domestic structures and religious vocations of its fellow states as realities and refrain from challenging their existence. With a balance of power now perceived as natural and desirable, the ambitions of rulers would be set in counterpoise against each other, at least in theory curtailing the scope of conflicts. Division and multiplicity, an accident of Europe’s history, became the hallmarks of a new system of international order with its own distinct philosophical outlook. In this sense the European effort to end its conflagration shaped and prefigured the modern sensibility: it reserved judgment on the absolute in favor of the practical and ecumenical; it sought to distill order from multiplicity and restraint.

The seventeenth-century negotiators who crafted the Peace of Westphalia did not think they were laying the foundation for a globally applicable system. They made no attempt to include neighboring Russia, which was then reconsolidating its own order after the nightmarish “Time of Troubles” by enshrining principles distinctly at odds with Westphalian balance: a single absolute ruler, a unified religious orthodoxy, and a program of territorial expansion in all directions. Nor did the other major power centers regard the Westphalian settlement (to the extent they learned of it at all) as relevant to their own regions.

The idea of world order was applied to the geographic extent known to the statesmen of the time—a pattern repeated in other regions. This was largely because the then-prevailing technology did not encourage or even permit the operation of a single global system. With no means of interacting with each other on a sustained basis and no framework for measuring the power of one region against another, each region viewed its own order as unique and defined the others as “barbarians”—governed in a manner incomprehensible to the established system and irrelevant to its designs except as a threat. Each defined itself as a template for the legitimate organization of all humanity, imagining that in governing what lay before it, it was ordering the world.

At the opposite end of the Eurasian landmass from Europe, China was the center of its own hierarchical and theoretically universal concept of order. This system had operated for millennia—it had been in place when the Roman Empire governed Europe as a unity—basing itself not on the sovereign equality of states but on the presumed boundlessness of the Emperor’s reach. In this concept, sovereignty in the European sense did not exist, because the Emperor held sway over “All Under Heaven.” He was the pinnacle of a political and cultural hierarchy, distinct and universal, radiating from the center of the world in the Chinese capital outward to all the rest of humankind. The latter were classified as various degrees of barbarians depending in part on their mastery of Chinese writing and cultural institutions (a cosmography that endured well into the modern era). China, in this view, would order the world primarily by awing other societies with its cultural magnificence and economic bounty, drawing them into relationships that could be managed to produce the aim of “harmony under heaven.”

In much of the region between Europe and China, Islam’s different universal concept of world order held sway, with its own vision of a single divinely sanctioned governance uniting and pacifying the world. In the seventh century, Islam had launched itself across three continents in an unprecedented wave of religious exaltation and imperial expansion. After unifying the Arab world, taking over remnants of the Roman Empire, and subsuming the Persian Empire, Islam came to govern the Middle East, North Africa, large swaths of Asia, and portions of Europe. Its version of universal order considered Islam destined to expand over the “realm of war,” as it called all regions populated by unbelievers, until the whole world was a unitary system brought into harmony by the message of the Prophet Muhammad. As Europe built its multistate order, the Turkish-based Ottoman Empire revived this claim to a single legitimate governance and spread its supremacy through the Arab heartland, the Mediterranean, the Balkans, and Eastern Europe. It was aware of Europe’s nascent interstate order; it considered it not a model but a source of division to be exploited for westward Ottoman expansion. As Sultan Mehmed the Conqueror admonished the Italian city-states practicing an early version of multipolarity in the fifteenth century, “You are 20 states . . . you are in disagreement among yourselves . . . There must be only one empire, one faith, and one sovereignty in the world.”

Meanwhile, across the Atlantic the foundations of a distinct vision of world order were being laid in the “New World.” As Europe’s seventeenth-century political and sectarian conflicts raged, Puritan settlers had set out to redeem God’s plan with an “errand in the wilderness” that would free them from adherence to established (and in their view corrupted) structures of authority. There they would build, as Governor John Winthrop preached in 1630 aboard a ship bound for the Massachusetts settlement, a “city upon a hill,” inspiring the world through the justness of its principles and the power of its example. In the American view of world order, peace and balance would occur naturally, and ancient enmities would be set aside—once other nations were given the same principled say in their own governance that Americans had in theirs. The task of foreign policy was thus not so much the pursuit of a specifically American interest as the cultivation of shared principles. In time, the United States would become the indispensable defender of the order Europe designed. Yet even as the United States lent its weight to the effort, an ambivalence endured—for the American vision rested not on an embrace of the European balance-of-power system but on the achievement of peace through the spread of democratic principles.

Of all these concepts of order, Westphalian principles are, at this writing, the sole generally recognized basis of what exists of a world order. The Westphalian system spread around the world as the framework for a state-based international order spanning multiple civilizations and regions because, as the European nations expanded, they carried the blueprint of their international order with them. While they often neglected to apply concepts of sovereignty to the colonies and colonized peoples, when these peoples began to demand their independence, they did so in the name of Westphalian concepts. The principles of national independence, sovereign statehood, national interest, and noninterference proved effective arguments against the colonizers themselves during the struggles for independence and protection for their newly formed states afterward.

The contemporary, now global Westphalian system—what colloquially is called the world community—has striven to curtail the anarchical nature of the world with an extensive network of international legal and organizational structures designed to foster open trade and a stable international financial system, establish accepted principles of resolving international disputes, and set limits on the conduct of wars when they do occur. This system of states now encompasses every culture and region. Its institutions have provided the neutral framework for the interactions of diverse societies—to a large extent independent of their respective values.

Yet Westphalian principles are being challenged on all sides, sometimes in the name of world order itself. Europe has set out to depart from the state system it designed and to transcend it through a concept of pooled sovereignty. And ironically, though Europe invented the balance-of-power concept, it has consciously and severely limited the element of power in its new institutions. Having downgraded its military capacities, Europe has little scope to respond when universal norms are flouted.

In the Middle East, jihadists on both sides of the Sunni-Shia divide tear at societies and dismantle states in quest of visions of global revolution based on the fundamentalist version of their religion. The state itself—as well as the regional system based on it—is in jeopardy, assaulted by ideologies rejecting its constraints as illegitimate and by terrorist militias that, in several countries, are stronger than the armed forces of the government.

Asia, in some ways the most strikingly successful of the regions to adopt concepts of sovereign statehood, still recalls alternative concepts of order with nostalgia and churns with rivalries and historical claims of the kind that dashed Europe’s order a century ago. Nearly every country considers itself to be “rising,” driving disagreements to the edge of confrontation.

The United States has alternated between defending the Westphalian system and castigating its premises of balance of power and noninterference in domestic affairs as immoral and outmoded, and sometimes both at once. It continues to assert the universal relevance of its values in building a peaceful world order and reserves the right to support them globally. Yet after withdrawing from three wars in two generations—each begun with idealistic aspirations and widespread public support but ending in national trauma—America struggles to define the relationship between its power (still vast) and its principles.

All of the major centers of power practice elements of Westphalian order to some degree, but none considers itself the natural defender of the system. All are undergoing significant internal shifts. Can regions with such divergent cultures, histories, and traditional theories of order vindicate the legitimacy of any common system?

Success in such an effort will require an approach that respects both the multifariousness of the human condition and the ingrained human quest for freedom. Order in this sense must be cultivated; it cannot be imposed. This is particularly so in an age of instantaneous communication and revolutionary political flux. Any system of world order, to be sustainable, must be accepted as just—not only by leaders, but also by citizens. It must reflect two truths: order without freedom, even if sustained by momentary exaltation, eventually creates its own counterpoise; yet freedom cannot be secured or sustained without a framework of order to keep the peace. Order and freedom, sometimes described as opposite poles on the spectrum of experience, should instead be understood as interdependent. Can today’s leaders rise above the urgency of day-to-day events to achieve this balance?

An answer to these questions must deal with three levels of order. World order describes the concept held by a region or civilization about the nature of just arrangements and the distribution of power thought to be applicable to the entire world. An international order is the practical application of these concepts to a substantial part of the globe—large enough to affect the global balance of power. Regional orders involve the same principles applied to a defined geographic area.

Any one of these systems of order bases itself on two components: a set of commonly accepted rules that define the limits of permissible action and a balance of power that enforces restraint where rules break down, preventing one political unit from subjugating all others. A consensus on the legitimacy of existing arrangements does not—now or in the past—foreclose competitions or confrontations, but it helps ensure that they will occur as adjustments within the existing order rather than as fundamental challenges to it. A balance of forces does not in itself secure peace, but if thoughtfully assembled and invoked, it can limit the scope and frequency of fundamental challenges and curtail their chance of succeeding when they do occur.

No book can hope to address every historic approach to international order or every country now active in shaping world affairs. This volume attempts to deal with the regions whose concepts of order have most shaped the evolution of the modern era.

The balance between legitimacy and power is extremely complex; the smaller the geographic area to which it applies and the more coherent the cultural convictions within it, the easier it is to distill a workable consensus. But in the modern world the need is for a global world order. An array of entities unrelated to each other by history or values (except at arm’s length), and defining themselves essentially by the limit of their capabilities, is likely to generate conflict, not order.

During my first visit to Beijing, undertaken in 1971 to reestablish contact with China after two decades of hostility, I mentioned that to the American delegation, China was a “land of mystery.” Premier Zhou Enlai responded, “You will find it not mysterious. When you have become familiar with it, it will not seem so mysterious as before.” There were 900 million Chinese, he observed, and it seemed perfectly normal to them. In our time, the quest for world order will require relating the perceptions of societies whose realities have largely been self-contained. The mystery to be overcome is one all peoples share—how divergent historic experiences and values can be shaped into a common order.

The history of most civilizations is a tale of the rise and fall of empires. Order was established by their internal governance, not through an equilibrium among states: strong when the central authority was cohesive, more haphazard under weaker rulers. In imperial systems, wars generally took place at the frontiers of the empire or as civil wars. Peace was identified with the reach of imperial power.

In China and Islam, political contests were fought for control of an established framework of order. Dynasties changed, but each new ruling group portrayed itself as restoring a legitimate system that had fallen into disrepair. In Europe, no such evolution took hold. With the end of Roman rule, pluralism became the defining characteristic of the European order. The idea of Europe loomed as a geographic designation, as an expression of Christianity or of court society, or as the center of enlightenment of a community of the educated and of modernity. Yet although it was comprehensible as a single civilization, Europe never had a single governance, or a united, fixed identity. It changed the principles in the name of which its various units governed themselves at frequent intervals, experimenting with a new concept of political legitimacy or international order.

In other regions of the world, a period of competing rulers came by posterity to be regarded as a “time of troubles,” a civil war, or a “warlord period”—a lamented interlude of disunity that had been transcended. Europe thrived on fragmentation and embraced its own divisions. Distinct competing dynasties and nationalities were perceived not as a form of “chaos” to be expunged but, in the idealized view of Europe’s statesmen—sometimes conscious, sometimes not—as an intricate mechanism tending toward a balance that preserved each people’s interests, integrity, and autonomy. For more than a thousand years, in the mainstream of modern European statecraft order has derived from equilibrium, and identity from resistance to universal rule. It is not that European monarchs were more immune to the glories of conquest than their counterparts in other civilizations or more committed to an ideal of diversity in the abstract. Rather, they lacked the strength to impose their will on each other decisively. In time, pluralism took on the characteristics of a model of world order. Has Europe in our time transcended this pluralistic tendency—or do the internal struggles of the European Union affirm it?

For five hundred years, Rome’s imperial rule had ensured a single set of laws, a common defense, and an extraordinary level of civilization. With the fall of Rome, conventionally dated in 476, the empire disintegrated. In what historians have called the Dark Ages, nostalgia for the lost universality flourished. The vision of harmony and unity focused increasingly on the Church. In that worldview, Christendom was a single society administered by two complementary authorities: civil government, the “successors of Caesar” maintaining order in the temporal sphere; and the Church, the successors of Peter tending to universal and absolute principles of salvation. Augustine of Hippo, writing in North Africa as Roman rule crumbled, theologically concluded that temporal political authority was legitimate to the extent that it furthered the pursuit of a God-fearing life and with it man’s salvation. “There are two systems,” Pope Gelasius I wrote to the Byzantine Emperor Anastasius in A.D. 494, “under which this world is governed, the sacred authority of the priests and the royal power. Of these, the greater weight is with the priests in so far as they will answer to the Lord, even for kings, in the Last Judgment.” The real world order was in this sense not in this world.

This all-encompassing concept of world order had to contend with an anomaly from the start: in the post–Roman Europe, dozens of political rulers exercised sovereignty with no clear hierarchy among them; all invoked fealty to Christ, but their link to the Church and its authority was ambiguous. Fierce debates attended the delineation of Church authority, while kingdoms with separate militaries and independent policies maneuvered for advantage in a manner that bore no apparent relationship to Augustine’s City of God.

Aspirations to unity were briefly realized on Christmas Day 800, when Pope Leo III crowned Charlemagne, the Frankish King and conqueror of much of present-day France and Germany, as Imperator Romanorum (Emperor of the Romans), and awarded him theoretical title to the former eastern half of the erstwhile Roman Empire, at that point the lands of Byzantium. The Emperor pledged to the Pope “to defend on all sides the holy church of Christ from pagan incursion and infidel devastation abroad, and within to add strength to the Catholic faith by our recognition of it.”

But Charlemagne’s empire did not fulfill its aspirations: in fact it began to crumble almost as soon as it was inaugurated. Charlemagne, beset by tasks closer to home, never attempted to rule the lands of the erstwhile Eastern Roman Empire the Pope had allotted him. In the west, he made little progress in recapturing Spain from its Moorish conquerors. After Charlemagne’s death, his successors sought to reinforce his position by appeal to tradition, by naming his possessions the Holy Roman Empire. But debilitated by civil wars, less than a century after its founding, Charlemagne’s empire passed from the scene as a coherent political entity (though its name remained in use throughout a shifting series of territories until 1806).

China had its Emperor; Islam had its Caliph—the recognized leader of the lands of Islam. Europe had the Holy Roman Emperor. But the Holy Roman Emperor operated from a much weaker base than his confreres in other civilizations. He had no imperial bureaucracy at his disposal. His authority depended on his strength in the regions he governed in his dynastic capacity, essentially his family holdings. His position was not formally hereditary and depended on election by a franchise of seven, later nine, princes; these elections were generally decided by a mixture of political maneuvering, assessments of religious piety, and vast financial payoffs. The Emperor theoretically owed his authority to his investiture by the Pope, but political and logistical considerations often excluded it, leaving him to rule for years as “Emperor-Elect.” Religion and politics never merged into a single construct, leading to Voltaire’s truthful jest that the Holy Roman Empire was “neither Holy, nor Roman, nor an Empire.” Medieval Europe’s concept of international order reflected a case-by-case accommodation between the Pope and the Emperor and a host of other feudal rulers. A universal order based on the possibility of a single reign and a single set of legitimating principles was increasingly drained of any practicality.

A full flowering of the medieval concept of world order was envisioned only briefly with the rise of the sixteenth-century Habsburg prince Charles (1500–1558); his rule also ushered in its irrevocable decay. The stern and pious Flemish-born prince was born to rule; except for a widely noted taste for spiced food, he was generally perceived to be without vices and immune to distraction. He inherited the crown of the Netherlands as a child and that of Spain—with its vast and expanding array of colonies in Asia and the Americas—at sixteen. Shortly after, in 1519, he prevailed in the election for the post of Holy Roman Emperor, making him Charlemagne’s formal successor. The coincidence of these titles meant that the medieval vision seemed poised to be fulfilled. A single, pious ruler now governed territories approximately equivalent to today’s Austria, Germany, northern Italy, Czech Republic, Slovakia, Hungary, eastern France, Belgium, Netherlands, Spain, and much of the Americas. (This massive agglomeration of political power was accomplished almost entirely through strategic marriages and gave rise to the Habsburg saying “Bella gerant alii; tu, felix Austria, nube!”—“Leave the waging of wars to others; you, happy Austria, marry!”) Spanish explorers and conquistadores—Magellan and Cortés sailed under Charles’s auspices—were in the process of destroying the ancient empires of the Americas and carrying the sacraments together with European political power across the New World. Charles’s armies and navies were engaged in the defense of Christendom against a new wave of invasions, by the Ottoman Turks and their surrogates in southeastern Europe and North Africa. Charles personally led a counterattack in Tunisia, with a fleet funded by gold from the New World. Caught up in these heady developments, Charles was hailed by his contemporaries as the “greatest emperor since the division of the empire in 843,” destined to return the world to “a single shepherd.”

In the tradition of Charlemagne, at his coronation Charles vowed to be “the protector and defender of the Holy Roman Church,” and crowds paid him obeisance as “Caesare” and “Imperio”; Pope Clement affirmed Charles as the temporal force for “seeing peace and order reestablished” in Christendom.

A Chinese or Turkish visitor to Europe at that time might well have perceived a seemingly familiar political system: a continent presided over by a single dynasty imbued with a sense of divine mandate. If Charles had been able to consolidate his authority and manage an orderly succession in the vast Habsburg territorial conglomerate, Europe would have been shaped by a dominant central authority like the Chinese Empire or the Islamic caliphate.

It did not happen; nor did Charles try. In the end, he was satisfied to base order on equilibrium. Hegemony might be his inheritance but not his objective, as he proved when, after capturing his temporal political rival the French King Francis I in the Battle of Pavia in 1525, he released him—freeing France to resume a separate and adversarial foreign policy at the heart of Europe. The French King repudiated Charles’s grand gesture by taking the remarkable step—so at odds with the medieval concept of Christian statecraft—of proposing military cooperation to the Ottoman Sultan Suleiman, who was then invading Eastern Europe and challenging Habsburg power from the east.

The universality of the Church Charles sought to vindicate was not to be had. He proved unable to prevent the new doctrine of Protestantism from spreading through the lands that were the principal base of his power. Both religious and political unity were fracturing. The effort to fulfill his aspirations inherent in his office was beyond the capabilities of a single individual. A haunting portrait by Titian from 1548 at Munich’s Alte Pinakothek reveals the torment of an eminence who cannot reach spiritual fulfillment or manipulate the, to him, ultimately secondary levers of hegemonic rule. Charles resolved to abdicate his dynastic titles and divide his vast empire, and did so in a manner reflecting the pluralism that had defeated his quest for unity. To his son Philip, he bequeathed the Kingdom of Naples and Sicily, then the crown of Spain and its global empire. In an emotional 1555 ceremony in Brussels, he reviewed the record of his reign, attested to the diligence with which he had fulfilled his duties, and in the process handed the States-General of the Netherlands to Philip as well. The same year, Charles concluded a landmark treaty, the Peace of Augsburg, which recognized Protestantism within the Holy Roman Empire. Abandoning the spiritual foundation of his empire, Charles afforded princes the right to choose the confessional orientation of their territory. Shortly afterward, he resigned his title as Holy Roman Emperor, passing responsibility for the empire, its upheavals, and its external challenges to his brother Ferdinand. Charles retired to a monastery in a rural region of Spain, to a life of seclusion. He spent his last days in the company of his confessor and of an Italian clock maker, whose works lined the walls and whose trade Charles attempted to learn. When Charles died in 1558, his will expressed regret for the fracturing of doctrine that had taken place during his reign and charged his son to redouble the Inquisition.

Three events completed the disintegration of the old ideal of unity. By the time Charles V died, revolutionary changes had raised Europe’s sights from a regional to a global enterprise while fragmenting the medieval political and religious order: the beginning of the age of discovery, the invention of printing, and the schism in the Church.

A map depicting the universe, as comprehended by educated Europeans in the medieval age, would have shown Northern and Southern Hemispheres stretching from India in the east to Iberia and the islands of Britain in the west, with Jerusalem in the center. In the medieval perception, this was not a map for travelers but a stage divinely ordained for the drama of human redemption. The world, it was believed on biblical authority, was six-sevenths land and one-seventh water. Because the principles of salvation were fixed and could be cultivated through efforts in the lands known to Christendom, there was no reward for venturing past the fringes of civilization. In the Inferno, Dante described Ulysses’ sailing out through the Pillars of Hercules (the Rock of Gibraltar and the adjacent heights of North Africa, at the western edge of the Mediterranean Sea) in search of knowledge, and being punished for his transgression against God’s plan by a whirlwind that dooms his ship and all its crew.

The modern era announced itself when enterprising societies sought glory and wealth by exploring the oceans and whatever lay beyond them. In the fifteenth century, Europe and China ventured forth almost contemporaneously. Chinese ships, then the world’s largest and technologically most advanced, undertook journeys of exploration reaching Southeast Asia, India, and the east coast of Africa. They exchanged presents with local dignitaries, enrolled princes in China’s imperial “tribute system,” and brought home with them cultural and zoological curiosities. Yet following the head navigator Zheng He’s death in 1433, the Chinese Emperor put an end to overseas adventures, and the fleet was abandoned. China continued to insist on the universal relevance of its principles of world order, but it would henceforth cultivate them at home and with the peoples along its borders. It never again attempted a comparable naval effort—until perhaps our own time.

Sixty years later, the European powers sailed from a continent of competing sovereign authorities; each monarch sponsored naval exploration largely in the hope of achieving a commercial or strategic edge over his rivals. Portuguese, Dutch, and English ships ventured to India; Spanish and English ships journeyed to the Western Hemisphere. Both began to displace the existing trade monopolies and political structures. The age of three centuries of preponderant European influence in world affairs had been launched. International relations, once a regional enterprise, would henceforth be geographically global, with the center of gravity in Europe, in which the concept of world order was defined and its implementation determined.

A revolution of thinking about the nature of the political universe followed. How was one to conceive of the inhabitants of regions no one had known existed? How did they fit into the medieval cosmology of empire and papacy? A council of theologians summoned by Charles V in 1550–51 in the Spanish city of Valladolid had concluded that the people living in the Western Hemisphere were human beings with souls—hence eligible for salvation. This theological conclusion was, of course, also a maxim justifying conquest and conversion. Europeans were enabled to increase their wealth and salve their consciences simultaneously. Their global competition for territorial control changed the nature of international order. Europe’s perspective expanded—until successive colonial efforts by various European states covered most of the globe and concepts of world order merged with the operation of the balance of power in Europe.

The second seminal event was the invention of movable-type printing in the middle of the fifteenth century, which made it possible to share knowledge on a hitherto-unimaginable scale. Medieval society had stored knowledge by memorizing or laboriously hand-copying religious texts or by understanding history through epic poetry. In the age of exploration, what was being discovered needed to be understood, and printing permitted accounts to be disseminated. The exploration of new worlds inspired as well a quest to rediscover the ancient world and its verities, with special emphasis on the centrality of the individual. The growing embrace of reason as an objective force of illumination and explication began to shake existing institutions, including the hitherto-unassailable Catholic Church.

The third revolutionary upheaval, that of the Protestant Reformation, was initiated when Martin Luther posted ninety-five theses on the door of the Wittenberg Castle Church in 1517, insisting on the individual’s direct relationship with God; hence individual conscience—not established orthodoxy—was put forward as the key to salvation. A number of feudal rulers seized the opportunity to enhance their authority by embracing Protestantism, imposing it on their populations, and enriching themselves by seizing Church lands. Each side regarded the other as heretical, and disagreements turned into life-or-death struggles as political and sectarian disputes commingled. The barrier separating domestic and foreign disputes collapsed as sovereigns backed rival factions in their neighbors’ domestic, often bloody, religious struggles. The Protestant Reformation destroyed the concept of a world order sustained by the “two swords” of papacy and empire. Christianity was split and at war with itself.

A century of intermittent wars attended the rise and spread of the Protestant critique of Church supremacy: the Habsburg Empire and the papacy both sought to stamp out the challenge to their authority, and Protestants resisted in defense of their new faith.

The period labeled by posterity as the Thirty Years’ War (1618–48) brought this turmoil to a climax. With an imperial succession looming and the Catholic King of Bohemia, the Habsburg Ferdinand, emerging as the most plausible candidate, the Protestant Bohemian nobility attempted an act of “regime change,” offering their crown—and its decisive electoral vote—to a Protestant German prince, an outcome in which the Holy Roman Empire would have ceased to be a Catholic institution. Imperial forces moved to crush the Bohemian rebellion and then pressed their advantage against Protestantism generally, triggering a war that devastated Central Europe. (The Protestant princes were generally located in the north of Germany, including the then relatively insignificant Prussia; the Catholic heartland was the south of Germany and Austria.)

In theory, the Emperor’s fellow Catholic sovereigns were obliged to unite in opposition to the new heresies. Yet faced with a choice between spiritual unity and strategic advantage, more than a few chose the latter. Foremost among them was France.

In a period of general upheaval, a country that maintains domestic authority is in a position to exploit chaos in neighboring states for larger international objectives. A cadre of sophisticated and ruthless French ministers saw their opportunity and moved decisively. The Kingdom of France began the process by giving itself a new governance. In feudal systems, authority was personal; governance reflected the ruler’s will but was also circumscribed by tradition, limiting the resources available for a country’s national or international actions. France’s chief minister from 1624 to 1642, Armand-Jean du Plessis, Cardinal de Richelieu, was the first statesman to overcome these limitations.

A man of the cloth steeped in court intrigue, Richelieu was well adapted to a period of religious upheaval and crumbling established structures. As the youngest of three sons from a minor noble family, he embarked on a military career but then switched to theology after his brother’s unexpected resignation from the bishopric of Luçon, considered a family birthright. Lore holds that Richelieu completed his religious studies so swiftly that he was below the normal minimum age for a clerical appointment; he resolved this obstacle by traveling to Rome and personally lying to the Pope about his age. His credentials obtained, he launched himself into factional politics at the French royal court, becoming first a close aide to the queen mother, Marie de’ Medici, and then a trusted advisor to her chief political rival, her minor son King Louis XIII. Both evinced a strong distrust of Richelieu, but wracked by internal conflicts with France’s Huguenot Protestants, they could not bring themselves to forgo his political and administrative genius. The young cleric’s mediation between these contending royals won him a recommendation to Rome for a cardinal’s hat; when given it, he became the highest-ranking member of the King’s privy council. Maintaining the role for nearly two decades, the “red eminence” (so called because of his flowing red cardinal’s robes) became France’s chief minister, the power behind the throne, and the charting genius of a new concept of centralized statecraft and foreign policy based on the balance of power.

When Richelieu conducted the policies of his country, Machiavelli’s treatises on statesmanship circulated. It is not known whether Richelieu was familiar with these texts on the politics of power. He surely practiced their essential principles. Richelieu developed a radical approach to international order. He invented the idea that the state was an abstract and permanent entity existing in its own right. Its requirements were not determined by the ruler’s personality, family interests, or the universal demands of religion. Its lodestar was the national interest following calculable principles—what later came to be known as raison d’état. Hence it should be the basic unit of international relations.

Richelieu commandeered the incipient state as an instrument of high policy. He centralized authority in Paris, created so-called intendants or professional stewards to project the government’s authority into every district of the kingdom, brought efficiency to the gathering of taxes, and decisively challenged traditional local authorities of the old nobility. Royal power would continue to be exercised by the King as the symbol of the sovereign state and an expression of the national interest.

Richelieu saw the turmoil in Central Europe not as a call to arms to defend the Church but as a means to check imperial Habsburg preeminence. Though France’s King had been styled as the Rex Catholicissimus, or the “Most Catholic King,” since the fourteenth century, France moved—at first unobtrusively, then openly—to support the Protestant coalition (of Sweden, Prussia, and the North German princes) on the basis of cold national-interest calculation.

To outraged complaints that, as a cardinal, he owed a duty to the universal and eternal Catholic Church—which would imply an alignment against the rebellious Protestant princes of Northern and Central Europe—Richelieu cited his duties as a minister to a temporal, yet vulnerable, political entity. Salvation might be his personal objective, but as a statesman he was responsible for a political entity that did not have an eternal soul to be redeemed. “Man is immortal, his salvation is hereafter,” he said. “The state has no immortality, its salvation is now or never.”

The fragmentation of Central Europe was perceived by Richelieu as a political and military necessity. The basic threat to France was strategic, not metaphysical or religious: a united Central Europe would be in a position to dominate the rest of the Continent. Hence it was in France’s national interest to prevent the consolidation of Central Europe: “If the [Protestant] party is entirely ruined, the brunt of the power of the House of Austria will fall on France.” France, by supporting a plethora of small states in Central Europe and weakening Austria, achieved its strategic objective.

Richelieu’s design would endure through vast upheavals. For two and a half centuries—from the emergence of Richelieu in 1624 to Bismarck’s proclamation of the German Empire in 1871—the aim of keeping Central Europe (more or less the territory of contemporary Germany, Austria, and northern Italy) divided remained the guiding principle of French foreign policy. For as long as this concept served as the essence of the European order, France was preeminent on the Continent. When it collapsed, so did France’s dominant role.

Three conclusions emerge from Richelieu’s career. First, the indispensable element of a successful foreign policy is a long-term strategic concept based on a careful analysis of all relevant factors. Second, the statesman must distill that vision by analyzing and shaping an array of ambiguous, often conflicting pressures into a coherent and purposeful direction. He (or she) must know where this strategy is leading and why. And, third, he must act at the outer edge of the possible, bridging the gap between his society’s experiences and its aspirations. Because repetition of the familiar leads to stagnation, no little daring is required.

In our time, the Peace of Westphalia has acquired a special resonance as the path breaker of a new concept of international order that has spread around the world. The representatives meeting to negotiate it were more focused at the time on considerations of protocol and status.

By the time representatives of the Holy Roman Empire and its two main adversaries, France and Sweden, agreed in principle to convene a peace conference, the conflict had ground on for twenty-three years. Another two years of battle transpired before the delegations actually met; in the meantime, each side maneuvered to strengthen its allies and internal constituencies.

Unlike other landmark agreements such as the Congress of Vienna in 1814–15 or the Treaty of Versailles in 1919, the Peace of Westphalia did not emerge from a single conference, and the setting was not one generally associated with a gathering of statesmen pondering transcendent questions of world order. Mirroring the variety of contenders in a war that had ranged from Spain to Sweden, the peace emerged from a series of separate arrangements made in two different Westphalian towns. Catholic powers, including 178 separate participants from the different states constituting the Holy Roman Empire, gathered in the Catholic city of Münster. Protestant powers gathered in the mixed Lutheran and Catholic city of Osnabrück, roughly thirty miles away. The 235 official envoys and their staffs took up residence in whatever rooms they could find in the two small cities, neither of which had ever been considered suitable for a large-scale event, let alone a congress of all European powers. The Swiss envoy “lodged above a wool weaver’s shop in a room that stank of sausage and fish oil,” while the Bavarian delegation secured eighteen beds for its twenty-nine members. With no official conference head or mediator and no plenary sessions, representatives met on an ad hoc basis and traveled in a neutral zone between the two cities to coordinate positions, sometimes meeting informally in towns in the middle. Some of the major powers stationed representatives in both cities. Combat continued in various parts of Europe throughout the talks, with shifting military dynamics affecting the course of the negotiations.

Most representatives had come with eminently practical instructions based on strategic interests. While they employed almost identical high-minded phrases about achieving a “peace for Christendom,” too much blood had been spilled to conceive of reaching this lofty goal through doctrinal or political unity. It was now taken for granted that peace would be built, if at all, through balancing rivalries.

The Peace of Westphalia that emerged from these convoluted discussions is probably the most frequently cited diplomatic document in European history, though in fact no single treaty exists to embody its terms. Nor did the delegates ever meet in a single plenary session to adopt it. The peace is in reality the sum of three separate complementary agreements signed at different times in different cities. In the January 1648 Peace of Münster, Spain recognized the independence of the Dutch Republic, capping an eight-decades-long Dutch revolt that had merged with the Thirty Years’ War. In October 1648, separate groupings of powers signed the Treaty of Münster and the Treaty of Osnabrück, with terms mirroring each other and incorporating key provisions by reference.

Both of the main multilateral treaties proclaimed their intent as “a Christian, universal, perpetual, true, and sincere peace and friendship” for “the glory of God and the security of Christendom.” The operative terms were not substantially different from other documents of the period. Yet the mechanisms through which they were to be reached were unprecedented. The war had shattered pretensions to universality or confessional solidarity. Begun as a struggle of Catholics against Protestants, particularly after France’s entry against the Catholic Holy Roman Empire it had turned into a free-for-all of shifting and conflicting alliances. Much like the Middle Eastern conflagrations of our own period, sectarian alignments were invoked for solidarity and motivation in battle but were just as often discarded, trumped by clashes of geopolitical interests or simply the ambitions of outsized personalities. Every party had been abandoned at some point during the war by its “natural” allies; none signed the documents under the illusion that it was doing anything but advancing its own interests and prestige.

Paradoxically, this general exhaustion and cynicism allowed the participants to transform the practical means of ending a particular war into general concepts of world order. With dozens of battle-hardened parties meeting to secure hard-won gains, old forms of hierarchical deference were quietly discarded. The inherent equality of sovereign states, regardless of their power or domestic system, was instituted. Newly arrived powers, such as Sweden and the Dutch Republic, were granted protocol treatment equal to that of established great powers like France and Austria. All kings were referred to as “majesty” and all ambassadors “excellency.” This novel concept was carried so far that the delegations, demanding absolute equality, devised a process of entering the sites of negotiations through individual doors, requiring the construction of many entrances, and advancing to their seats at equal speed so that none would suffer the ignominy of waiting for the other to arrive at his convenience.

The Peace of Westphalia became a turning point in the history of nations because the elements it set in place were as uncomplicated as they were sweeping. The state, not the empire, dynasty, or religious confession, was affirmed as the building block of European order. The concept of state sovereignty was established. The right of each signatory to choose its own domestic structure and religious orientation free from intervention was affirmed, while novel clauses ensured that minority sects could practice their faith in peace and be free from the prospect of forced conversion. Beyond the immediate demands of the moment, the principles of a system of “international relations” were taking shape, motivated by the common desire to avoid a recurrence of total war on the Continent. Diplomatic exchanges, including the stationing of resident representatives in the capitals of fellow states (a practice followed before then generally only by Venetians), were designed to regulate relations and promote the arts of peace. The parties envisioned future conferences and consultations on the Westphalian model as forums for settling disputes before they led to conflict. International law, developed by traveling scholar-advisors such as Hugo de Groot (Grotius) during the war, was treated as an expandable body of agreed doctrine aimed at the cultivation of harmony, with the Westphalian treaties themselves at its heart.

The genius of this system, and the reason it spread across the world, was that its provisions were procedural, not substantive. If a state would accept these basic requirements, it could be recognized as an international citizen able to maintain its own culture, politics, religion, and internal policies, shielded by the international system from outside intervention. The ideal of imperial or religious unity—the operating premise of Europe’s and most other regions’ historical orders—had implied that in theory only one center of power could be fully legitimate. The Westphalian concept took multiplicity as its starting point and drew a variety of multiple societies, each accepted as a reality, into a common search for order. By the mid-twentieth century, this international system was in place on every continent; it remains the scaffolding of international order such as it now exists.

The Peace of Westphalia did not mandate a specific arrangement of alliances or a permanent European political structure. With the end of the universal Church as the ultimate source of legitimacy, and the weakening of the Holy Roman Emperor, the ordering concept for Europe became the balance of power—which, by definition, involves ideological neutrality and adjustment to evolving circumstances. The nineteenth-century British statesman Lord Palmerston expressed its basic principle as follows: “We have no eternal allies, and we have no perpetual enemies. Our interests are eternal and perpetual, and those interests it is our duty to follow.” Asked to define these interests more specifically in the form of an official “foreign policy,” the acclaimed steward of British power professed, “When people ask me . . . for what is called a policy, the only answer is that we mean to do what may seem to be best, upon each occasion as it arises, making the Interests of Our Country one’s guiding principle.” (Of course this deceptively simple concept worked for Britain in part because its ruling class was trained in a common, almost intuitive sense of what the country’s enduring interests were.)

Today these Westphalian concepts are often maligned as a system of cynical power manipulation, indifferent to moral claims. Yet the structure established in the Peace of Westphalia represented the first attempt to institutionalize an international order on the basis of agreed rules and limits and to base it on a multiplicity of powers rather than the dominance of a single country. The concepts of raison d’état and the “national interest” made their first appearance, representing not an exaltation of power but an attempt to rationalize and limit its use. Armies had marched across Europe for generations under the banner of universal (and contradictory) moral claims; prophets and conquerors had unleashed total war in pursuit of a mixture of personal, dynastic, imperial, and religious ambitions. The theoretically logical and predictable intermeshing of state interests was intended to overcome the disorder unfolding in every corner of the Continent. Limited wars over calculable issues would replace the era of contending universalisms, with its forced expulsions and conversions and general war consuming civilian populations.

With all its ambiguities, the balancing of power was thought an improvement over the exactions of religious wars. But how was the balance of power to be established? In theory, it was based on realities; hence every participant in it should see it alike. But each society’s perceptions are affected by its domestic structure, culture, and history and by the overriding reality that the elements of power—however objective—are in constant flux. Hence the balance of power needs to be recalibrated from time to time. It produces the wars whose extent it also limits.

With the Treaty of Westphalia, the papacy had been confined to ecclesiastical functions, and the doctrine of sovereign equality reigned. What political theory could then explain the origin and justify the functions of secular political order? In his Leviathan,published in 1651, three years after the Peace of Westphalia, Thomas Hobbes provided such a theory. He imagined a “state of nature” in the past when the absence of authority produced a “war of all against all.” To escape such intolerable insecurity, he theorized, people delivered their rights to a sovereign power in return for the sovereign’s provision of security for all within the state’s borders. The sovereign state’s monopoly on power was established as the only way to overcome the perpetual fear of violent death and war.

This social contract in Hobbes’s analysis did not apply beyond the borders of states, for no supranational sovereign existed to impose order. Therefore:

Concerning the offices of one sovereign to another, which are comprehended in that law which is commonly called the law of nations, I need not say anything in this place, because the law of nations and the law of nature is the same thing. And every sovereign hath the same right, in procuring the safety of his people, that any particular man can have, in procuring the safety of his own body.

The international arena remained in the state of nature and was anarchical because there was no world sovereign available to make it secure and none could be practically constituted. Thus each state would have to place its own national interest above all in a world where power was the paramount factor. Cardinal Richelieu would have emphatically agreed.

The Peace of Westphalia in its early practice implemented a Hobbesian world. How was this new balance of power to be calibrated? A distinction must be made between the balance of power as a fact and the balance of power as a system. Any international order—to be worthy of that name—must sooner or later reach an equilibrium, or else it will be in a constant state of warfare. Because the medieval world contained dozens of principalities, a practical balance of power frequently existed in fact. After the Peace of Westphalia, the balance of power made its appearance as a system; that is to say, bringing it about was accepted as one of the key purposes of foreign policy; disturbing it would evoke a coalition on behalf of equilibrium.

The rise of Britain as a major naval power by early in the eighteenth century made it possible to turn the facts of the balance of power into a system. Control of the seas enabled Britain to choose the timing and scale of its involvement on the Continent to act as the arbiter of the balance of power, indeed the guarantor that Europe would have a balance of power at all. So long as England assessed its strategic requirements correctly, it would be able to back the weaker side on the Continent against the stronger, preventing any single country from achieving hegemony in Europe and thereby mobilizing the resources of the Continent to challenge Britain’s control of the seas. Until the outbreak of World War I, England acted as the balancer of the equilibrium. It fought in European wars but with shifting alliances—not in pursuit of specific, purely national goals, but by identifying the national interest with the preservation of the balance of power. Many of these principles apply to America’s role in the contemporary world, as will be discussed later.

There were in fact two balances of power being conducted in Europe after the Westphalian settlement: The overall balance, of which England acted as a guardian, was the protector of general stability. A Central European balance essentially manipulated by France aimed to prevent the emergence of a unified Germany in a position to become the most powerful country on the Continent. For more than two hundred years, these balances kept Europe from tearing itself to pieces as it had during the Thirty Years’ War; they did not prevent war, but they limited its impact because equilibrium, not total conquest, was the goal.

The balance of power can be challenged in at least two ways: The first is if a major country augments its strength to a point where it threatens to achieve hegemony. The second occurs when a heretofore-secondary state seeks to enter the ranks of the major powers and sets off a series of compensating adjustments by the other powers until a new equilibrium is established or a general conflagration takes place. The Westphalian system met both tests in the eighteenth century, first by thwarting the thrust for hegemony by France’s Louis XIV, then by adjusting the system to the insistence of Prussia’s Frederick the Great for equal status.

Louis XIV took full control of the French crown in 1661 and developed Richelieu’s concept of governance to unprecedented levels. The French King had in the past ruled through feudal lords with their own autonomous claims to authority based on heredity. Louis governed through a royal bureaucracy dependent entirely on him. He downgraded courtiers of noble blood and ennobled bureaucrats. What counted was service to the King, not rank of birth. The brilliant Finance Minister Jean-Baptiste Colbert, son of a provincial draper, was charged with unifying the tax administration and financing constant war. The memoirs of Saint-Simon, a duke by inheritance and man of letters, bear bitter witness to the social transformation:

He [Louis] was well aware that though he might crush a nobleman with the weight of his displeasure, he could not destroy him or his line, whereas a secretary of state or other such minister could be reduced together with his whole family to those depths of nothingness from which he had been elevated. No amount of wealth or possessions would avail him then. That was one reason why he liked to give his ministers authority over the highest in the Land, even over the Princes of the Blood.

In 1680, Louis symbolized the nature of his all-embracing rule by assuming the title “the Great” to go with his earlier self-granted appellation as “the Sun King.” In 1682, France’s North American territories were named “Louisiana.” The same year, Louis’s court moved to Versailles, where the King oversaw in elaborate detail a “theater monarchy” dedicated, above all, to the performance of his own majesty.

With a unified kingdom spared the ravages of internal war, possessing a skilled bureaucracy and a military surpassing that of any neighboring state, France was for a while in a position to seek dominance in Europe. Louis’s reign resolved itself into a series of almost continuous wars. In the end, as was the case with all later aspirants to European hegemony, each new conquest galvanized an opposing coalition of nations. At first, Louis’s generals won battles everywhere; ultimately, they were defeated or checked everywhere, most signally in the first decade of the eighteenth century by John Churchill, later Duke of Marlborough and forebear of the great twentieth-century Prime Minister Winston Churchill. Louis’s legions could not overcome the basic resilience of the Westphalian system.

Decades after Richelieu’s death, the demonstrated effectiveness of a consolidated, centralized state pursuing a secular foreign policy and centralized administration inspired imitators that united to counterbalance French power. England, Holland, and Austria created the Grand Alliance, joined later by Spain, Prussia, Denmark, and several German principalities. The opposition to Louis was not ideological or religious in nature: French remained the language of diplomacy and high culture through much of Europe, and the Catholic-Protestant divide ran through the allied camp. Rather, it was inherent in the Westphalian system and indispensable to preserve the pluralism of the European order. Its character was defined in the name contemporary observers gave it: the Great Moderation. Louis sought what amounted to hegemony in the name of the glory of France. He was defeated by a Europe that sought its order in diversity.

• • •

THE FIRST HALF of the eighteenth century was dominated by the quest to contain France; the second was shaped by Prussia’s effort to find a place for itself among the major powers. Where Louis had fought wars to translate power into hegemony, Prussia’s Frederick II went to war to transmute latent weakness into great-power status. Situated on the harsh North German plain and extending from the Vistula across Germany, Prussia cultivated discipline and public service to substitute for the larger population and greater resources of better-endowed countries. Split into two noncontiguous pieces, it jutted precariously into the Austrian, Swedish, Russian, and Polish spheres of influence. It was relatively sparsely populated; its strength was the discipline with which it marshaled its limited resources. Its greatest assets were civic-mindedness, an efficient bureaucracy, and a well-trained army.

When Frederick II ascended the throne in 1740, he seemed an unlikely contender for the greatness history has vouchsafed him. Finding the dour discipline of the position of Crown Prince oppressive, he had attempted to flee to England accompanied by a friend, Hans Hermann von Katte. They were apprehended. The King ordered von Katte decapitated in front of Frederick, whom he submitted to a court-martial headed by himself. He cross-examined his son with 178 questions, which Frederick answered so deftly that he was reinstated.

Surviving this searing experience was possible only by adopting his father’s austere sense of duty and developing a general misanthropic attitude toward his fellow man. Frederick saw his personal authority as absolute but his policies as limited rigidly by the principles of raison d’état Richelieu had put forward a century earlier. “Rulers are the slaves of their resources,” his credo held, “the interest of the State is their law, and this law may not be infringed.” Courageous and cosmopolitan (Frederick spoke and wrote French and composed sentimental French poetry even on military campaigns, subtitling one of his literary efforts “Pas trop mal pour la veille d’une grande bataille”), he embodied the new era of Enlightenment governance by benevolent despotism, which was legitimized by its effectiveness, not ideology.

Frederick concluded that great-power status required territorial contiguity for Prussia, hence expansion. There was no need for any other political or moral justification. “The superiority of our troops, the promptitude with which we can set them in motion, in a word the clear advantage we have over our neighbors” was all the justification Frederick required to seize the wealthy and traditionally Austrian province of Silesia in 1740. Treating the issue as a geopolitical, not a legal or moral, one, Frederick aligned himself with France (which saw in Prussia a counter to Austria) and retained Silesia in the peace settlement of 1742, nearly doubling Prussia’s territory and population.

In the process, Frederick brought war back to the European system, which had been at peace since 1713 when the Treaty of Utrecht had put an end to the ambitions of Louis XIV. The challenge to the established balance of power caused the Westphalian system to begin to function. The price for being admitted as a new member to the European order turned out to be seven years of near-disastrous battle. Now the alliances were reversed, as Frederick’s previous allies sought to quash his operations and their rivals tried to harness Prussia’s disciplined fighting force for their own aims. Russia, remote and mysterious, for the first time entered a contest over the European balance of power. At the edge of defeat, with Russian armies at the gates of Berlin, Frederick was saved by the sudden death of Czarina Elizabeth. The new Czar, a longtime admirer of Frederick, withdrew from the war. (Hitler, besieged in encircled Berlin in April 1945, waited for an event comparable to the so-called Miracle of the House of Brandenburg and was told by Joseph Goebbels that it had happened when President Franklin D. Roosevelt died.)

The Holy Roman Empire had become a facade; no rival European claimant to universal authority had arisen. Almost all rulers asserted that they ruled by divine right—a claim not challenged by any major power—but they accepted that God had similarly endowed many other monarchs. Wars were therefore fought for limited territorial objectives, not to overthrow existing governments and institutions, nor to impose a new system of relations between states. Tradition prevented rulers from conscripting their subjects and severely constrained their ability to raise taxes. The impact of wars on civilian populations was in no way comparable to the horrors of the Thirty Years’ War or what technology and ideology would produce two centuries later. In the eighteenth century, the balance of power operated as a theater in which “lives and values were put on display, amid splendor, polish, gallantry, and shows of utter self-assurance.” The exercise of that power was constrained by the recognition that the system would not tolerate hegemonic aspirations.

International orders that have been the most stable have had the advantage of uniform perceptions. The statesmen who operated the eighteenth-century European order were aristocrats who interpreted intangibles like honor and duty in the same way and agreed on fundamentals. They represented a single elite society that spoke the same language (French), frequented the same salons, and pursued romantic liaisons in each other’s capitals. National interests of course varied, but in a world where a foreign minister could serve a monarch of another nationality (every Russian foreign minister until 1820 was recruited abroad), or when a territory could change its national affiliation as the result of a marriage pact or a fortuitous inheritance, a sense of overarching common purpose was inherent. Power calculations in the eighteenth century took place against this ameliorating background of a shared sense of legitimacy and unspoken rules of international conduct.

This consensus was not only a matter of decorum; it reflected the moral convictions of a common European outlook. Europe was never more united or more spontaneous than during what came to be perceived as the age of enlightenment. New triumphs in science and philosophy began to displace the fracturing European certainties of tradition and faith. The swift advance of the mind on multiple fronts—physics, chemistry, astronomy, history, archaeology, cartography, rationality—bolstered a new spirit of secular illumination auguring that the revelation of all of nature’s hidden mechanisms was only a question of time. “The true system of the world has been recognized, developed, and perfected,” wrote the brilliant French polymath Jean Le Rond d’Alembert in 1759, embodying the spirit of the age:

In short, from the earth to Saturn, from the history of the heavens to that of insects, natural philosophy has been revolutionized; and nearly all other fields of knowledge have assumed new forms . . . [T]he discovery and application of a new method of philosophizing, the kind of enthusiasm which accompanies discoveries, a certain exaltation of ideas which the spectacle of the universe produces in us—all these causes have brought about a lively fermentation of minds. Spreading through nature in all directions like a river which has burst its dams, this fermentation has swept with a sort of violence everything along with it which stood in its way.

This “fermentation” based itself on a new spirit of analysis and a rigorous testing of all premises. The exploration and systematization of all knowledge—an endeavor symbolized by the twenty-eight-volume Encyclopédie that d’Alembert co-edited between 1751 and 1772—proclaimed a knowable, demystified universe with man as its central actor and explicator. Prodigious learning would be combined, d’Alembert’s colleague Denis Diderot wrote, with a “zeal for the best interests of the human race.” Reason would confront falsehoods with “solid principles [to] serve as the foundation for diametrically opposed truths,” whereby “we shall be able to throw down the whole edifice of mud and scatter the idle heap of dust” and instead “put men on the right path.”

Inevitably, this new way of thinking and analysis was applied to concepts of governance, political legitimacy, and international order. The political philosopher Charles-Louis de Secondat, Baron of Montesquieu, applied the principles of the balance of power to domestic policy by describing a concept of checks and balances later institutionalized in the American Constitution. He went on from there into a philosophy of history and of the mechanisms of societal change. Surveying the histories of various societies, Montesquieu concluded that events were never caused by accident. There was always an underlying cause that reason could discover and then shape to the common good:

It is not fortune which rules the world . . . There are general intellectual as well as physical causes active in every monarchy which bring about its rise, preservation, and fall. All [seeming] accidents are subject to these causes, and whenever an accidental battle, that is, a particular cause, has destroyed a state, a general cause also existed which led to the fall of this state as a result of a single battle. In short, it is the general pace of things which draws all particular events along with it.

The German philosopher Immanuel Kant, probably the greatest philosopher of the Enlightenment period, took Montesquieu a step further by developing a concept for a permanent peaceful world order. Pondering the world from the former Prussian capital of Königsberg, casting his gaze on the period of the Seven Years’ War, the American Revolutionary War, and the French Revolution, Kant dared to see in the general upheaval the faint beginnings of a new, more peaceful international order.

Humanity, Kant reasoned, was characterized by a distinctive “unsocial sociability”: the “tendency to come together in society, coupled, however, with a continual resistance which constantly threatens to break this society up.” The problem of order, particularly international order, was “the most difficult and the last to be solved by the human race.” Men formed states to constrain their passions, but like individuals in the state of nature each state sought to preserve its absolute freedom, even at the cost of “a lawless state of savagery.” But the “devastations, upheavals and even complete inner exhaustion of their powers” arising from interstate clashes would in time oblige men to contemplate an alternative. Humanity faced either the peace of “the vast graveyard of the human race” or peace by reasoned design.

The answer, Kant held, was a voluntary federation of republics pledged to non-hostility and transparent domestic and international conduct. Their citizens would cultivate peace because, unlike despotic rulers, when considering hostilities, they would be deliberating about “calling down on themselves all the miseries of war.” Over time the attractions of this compact would become apparent, opening the way toward its gradual expansion into a peaceful world order. It was Nature’s purpose that humanity eventually reason its way toward “a system of united power, hence a cosmopolitan system of general political security” and “a perfect civil union of mankind.”

The confidence, verging on brashness, in the power of reason reflected in part a species of what the Greeks called hubris—a kind of spiritual pride that bore the seeds of its own destruction within itself. The Enlightenment philosophers ignored a key issue: Can governmental orders be invented from scratch by intelligent thinkers, or is the range of choice limited by underlying organic and cultural realities (the Burkean view)? Is there a single concept and mechanism logically uniting all things, in a way that can be discovered and explicated (as d’Alembert and Montesquieu argued), or is the world too complicated and humanity too diverse to approach these questions through logic alone, requiring a kind of intuition and an almost esoteric element of statecraft?

The Enlightenment philosophers on the Continent generally opted for the rationalist rather than the organic view of political evolution. In the process, they contributed—unintentionally, indeed contrary to their intention—to an upheaval that rent Europe for decades and whose aftereffects reach to this day.

Revolutions are most unsettling when least expected. So it was with the French Revolution, which proclaimed a domestic and world order as different from the Westphalian system as it was possible to be. Abandoning the separation between domestic and foreign policy, it resurrected—and perhaps exceeded—the passions of the Thirty Years’ War, substituting a secular crusade for the religious impulse of the seventeenth century. It demonstrated how internal changes within societies are able to shake the international equilibrium more profoundly than aggression from abroad—a lesson that would be driven home by the upheavals of the twentieth century, many of which drew explicitly on the concepts first advanced by the French Revolution.

Revolutions erupt when a variety of often different resentments merge to assault an unsuspecting regime. The broader the revolutionary coalition, the greater its ability to destroy existing patterns of authority. But the more sweeping the change, the more violence is needed to reconstruct authority, without which society will disintegrate. Reigns of terror are not an accident; they are inherent in the scope of revolution.

The French Revolution occurred in the richest country of Europe, even though its government was temporarily bankrupt. Its original impetus is traceable to leaders—mostly aristocrats and upper bourgeoisie—who sought to bring the governance of their country into conformity with the principles of the Enlightenment. It gained a momentum not foreseen by those who made the Revolution and inconceivable to the prevailing ruling elite.

At its heart was a reordering on a scale that had not been seen in Europe since the end of the religious wars. For the revolutionaries, human order was the reflection of neither the divine plan of the medieval world, nor the intermeshing of grand dynastic interests of the eighteenth century. Like their progeny in the totalitarian movements of the twentieth century, the philosophers of the French Revolution equated the mechanism of history with the unadulterated operation of the popular will, which by definition could accept no inherent or constitutional limitation—and which they reserved to themselves the monopoly to identify. The popular will, as conceived in that manner, was altogether distinct from the concept of majority rule prevalent in England or of checks and balances embedded in a written constitution as in the United States. The claims of the French revolutionaries far exceeded Richelieu’s concept of the authority of the state by vesting sovereignty in an abstraction—not individuals but entire peoples as indivisible entities requiring uniformity of thought and action—and then designating themselves the people’s spokesmen and indeed embodiment.

The Revolution’s intellectual godfather, Jean-Jacques Rousseau, formulated this universal claim in a series of writings whose erudition and charm obscured their sweeping implications. Walking readers step by step through a “rational” dissection of human society, Rousseau condemned all existing institutions—property, religion, social classes, government authority, civil society—as illusory and fraudulent. Their replacement was to be a new “rule of administration in the social order.” The populace was to submit totally to it—with an obedience that no ruler by divine right had ever imagined, except the Russian Czar, whose entire populace outside the nobility and the communities on the harsh frontiers beyond the Urals had the status of serfs. These theories prefigured the modern totalitarian regime, in which the popular will ratifies decisions that have already been announced by means of staged mass demonstrations.

In pursuit of this ideology, all monarchies were by definition treated as enemies; because they would not give up power without resisting, the Revolution, to prevail, had to turn itself into a crusading international movement to achieve world peace by imposing its principles. In order to propel the new dispensation across Europe, France’s entire adult male population was made subject to conscription. The Revolution based itself on a proposition similar to that made by Islam a millennium before, and Communism in the twentieth century: the impossibility of permanent coexistence between countries of different religious or political conceptions of truth, and the transformation of international affairs into a global contest of ideologies to be fought by any available means and by mobilizing all elements of society. In doing so, the Revolution again merged domestic and foreign policy, legitimacy and power, whose decoupling by the Westphalian settlement had limited the scope and intensity of Europe’s wars. The concept of an international order with prescribed limits of state action was overthrown in favor of a permanent revolution that knew only total victory or defeat.

In November 1792, the French National Assembly threw down the gauntlet to Europe with a pair of extraordinary decrees. The first expressed an open-ended commitment to extend French military support to popular revolution anywhere. France, it announced, having liberated itself, “will accord fraternity and assistance to all peoples who shall wish to recover their liberty.” The National Assembly gave added weight to this decree and obliged itself to give it force in the proviso that the document be “translated and printed in all languages.” The National Assembly made the break with the eighteenth-century order irrevocable by guillotining France’s deposed King several weeks later. It also declared war on Austria and invaded the Netherlands.

In December 1792, an even more radical decree was issued with an even more universal application. Any revolutionary movement that thought the decree applied to it was invited to “fill in the blank” of a document reading, “The French People to the ____ People,” which applauded in advance the next fraternal revolution and pledged support to “the suppression of all the civil and military authorities which have governed you up to this day.” This process, whose scope was implicitly limitless, was also irreversible: “The French nation declares that it will treat as enemies the people who, refusing liberty and equality, or renouncing them, may wish to preserve, recall, or treat with the prince and the privileged castes.” Rousseau had written that “whoever refuses to obey the general will shall be forced to do so by the whole body . . . [H]e will be forced to be free.” The Revolution undertook to expand this definition of legitimacy to all humanity.

To achieve such vast and universal objectives, the leaders of the French Revolution strove to cleanse their country of all possibility of domestic opposition. “The Terror” killed thousands of the former ruling classes and all suspected domestic opponents, even those who supported the Revolution’s goals while questioning some of its methods. Two centuries later, comparable motivations underlay the Russian purges of the 1930s and the Chinese Cultural Revolution in the 1960s and 1970s.

Eventually, order was restored, as it must be if a state is not to disintegrate. The model once again came from Rousseau’s “great legislator.” Louis XIV had appropriated the state in the service of royal power; the Revolution commandeered the people to underwrite its design. Napoleon, who proclaimed himself “First Consul for Life,” later Emperor, represented a new type: the “Great Man” swaying the world by the force of his will, legitimized by charismatic magnetism and personal success in military command. The essence of the Great Man was his refusal to acknowledge traditional limits and his insistence on reordering the world by his own authority. At the climactic moment of his coronation as Emperor in 1804, Napoleon, unlike Charlemagne, refusing to be legitimized by a power other than his own, took the imperial crown from the Pope’s hands and crowned himself Emperor.

The Revolution no longer made the leader; the leader defined the Revolution. As he tamed the Revolution, Napoleon also made himself its guarantor. But he also saw himself—and not without reason—as the capstone of the Enlightenment. He rationalized France’s system of government, establishing the system of prefectures through which, even at this writing, the French system of administration operates. He created the Napoleonic Code, on which the laws that still prevail in France and other European countries are based. He was tolerant of religious diversity and encouraged rationalism in government, with the end of improving the lot of the French people.

It was as the simultaneous incarnation of the Revolution and expression of the Enlightenment that Napoleon set about to achieve the domination and unification of Europe. By 1809, under his brilliant military leadership, his armies crushed all opposition in Western and Central Europe, enabling him to redraw the map of the Continent as a geopolitical design. He annexed key territories to France and established satellite republics in others, many of them governed by relatives or French marshals. A uniform legal code was established throughout Europe. Thousands of instructions on matters economic and social were issued. Would Napoleon become the unifier of a continent divided since the fall of Rome?

Two obstacles remained: England and Russia. England, in command of the seas after Nelson’s crushing victory at Trafalgar in 1805, was for the moment invulnerable but not strong enough to launch a significant invasion across the English Channel. As it would a century and a half later, England stood alone in Western Europe, aware that a peace with the conqueror would make it possible for a single power to organize the resources of the entire Continent and, sooner or later, overcome its rule of the oceans. England waited behind the channel for Napoleon (and a century and a half later, for Hitler) to make a mistake that would enable it to reappear on the Continent militarily as a defender of the balance of power. (In World War II, Britain was also waiting for the United States to enter the lists.)

Napoleon had grown up under the eighteenth-century dynastic system and, in a strange way, accepted its legitimacy. In it, as a Corsican of minor standing even in his hometown, he was illegitimate by definition, which meant that, at least in his own mind, the legitimacy of his rule depended on the permanence—and, indeed, the extent—of his conquests. Whenever there remained a ruler independent of his will, Napoleon felt obliged to pursue him. Incapable of restraint by concept, temperament, or experience, he launched his forces into Spain and Russia, neither of them essential to a geopolitical design. Napoleon could not live in an international order; his ambition required an empire over at least the length and breadth of Europe, and for that his power fell just barely too short.