Luard designates 1789 as the start of the Age of Nationalism. The players in the preceding Age of Sovereignty had been sprawling dynastic empires that were not pinned to a "nation" in the sense of a group of people sharing a homeland, a language, and a culture. This new age was populated by states that were better aligned with nations and that competed with other nation-states for preeminence. Nationalist yearnings set off thirty wars of independence in Europe and led to autonomy for Belgium, Greece, Bulgaria, Albania, and Serbia. They also inspired the wars of national unification of Italy and of Germany. The peoples of Asia and Africa were not yet deemed worthy of national self-expression, so the European nation-states enhanced their own glory by colonizing them.

Of course, it all went horribly wrong. The French Revolution and the French Revolutionary and Napoleonic Wars caused as many as 4 million deaths, earning the sequence a spot in the twenty-one worst things people have ever done to each other, and poking up a major peak in the graph of war deaths in figure 5-18.

World War I, in this scheme, was a culmination of these nationalist longings. It was ignited by Serbian nationalism against the Habsburg Empire, inflamed by nationalist loyalties that pitted Germanic peoples against Slavic ones (and soon against the British and the French), and ended with the dismemberment of the multiethnic Habsburg and Ottoman empires into the new nation-states of Central and Eastern Europe.

Luard ends his Age of Nationalism in 1917. That was the year the United States entered the war and rebranded it as a struggle of democracy against autocracy, and in which the Russian Revolution created the first communist state. The world then entered the Age of Ideology, in which democracy and communism fought Nazism in World War II and each other during the Cold War. Writing in 1986, Luard dangled a dash after "1917"; today we might close it with "1989."

The concept of an Age of Nationalism is a bit procrustean. The age begins with the French Revolutionary and Napoleonic Wars because they were inflamed by the national spirit of France, but these wars were just as inflamed by the ideological residue of the French Revolution, well before the so-called Age of Ideology. Also, the age is an unwieldy sandwich, with massively destructive wars at each end and two record-breaking intervals of peace (1815-54 and 1871-1914) in the middle.

A better way to make sense of the past two centuries, Michael Howard has argued, is to see them as a battle for influence among four forces -- Enlightenment humanism, conservatism, nationalism, and utopian ideologies -- which sometimes joined up in temporary coalitions. Napoleonic France, because it emerged from the French Revolution, became associated in Europe with the French Enlightenment. In fact it is better classified as the first implementation of fascism. Though Napoleon did implement a few rational reforms such as the metric system and codes of civil law (which survive in many French-influenced regions today), in most ways he wrenched the clock back from the humanistic advances of the Enlightenment. He seized power in a coup, stamped out constitutional government, reinstituted slavery, glorified war, had the Pope crown him emperor, restored Catholicism as the state religion, installed three brothers and a brother-in-law on foreign thrones, and waged ruthless campaigns of territorial aggrandizement with a criminal disregard for human life.

Revolutionary and Napoleonic France, Bell has shown, were consumed by a combination of French nationalism and utopian ideology. The ideology, like the versions of Christianity that came before it and the fascism and communism that would follow it, was messianic, apocalyptic, expansionist, and certain of its own rectitude. And it viewed its opponents as irredeemably evil: as existential threats that had to be eliminated in pursuit of a holy cause. Bell notes that the militant utopianism was a disfigurement of the Enlightenment ideal of humanitarian progress. To the revolutionaries, Kant's "goal of perpetual peace had value not because it conformed to a fundamental moral law but because it conformed to the historical progress of civilization… And so they opened the door to the idea that in the name of future peace, any and all means might be justified -- including even exterminatory war." Kant himself despised this turn, noting that such a war "would allow perpetual peace only upon the graveyard of the whole human race." And the American framers, equally aware of the crooked timber of humanity, were positively phobic about the prospect of imperial or messianic leaders.

After the French ideology had been disseminated across Europe at the point of a bayonet and driven back at enormous cost, it elicited a slew of reactions, which as we saw in chapter 4 are often lumped together as counter-Enlightenments. Howard sees the common denominator as "the view that man is not simply an individual who by the light of reason and observation can formulate laws on the basis of which he can create a just and peaceful society, but rather a member of a community that has moulded him in a fashion he himself cannot fully comprehend, and which has a primary claim on his loyalties."

Recall that there were two counter-Enlightenments, which reacted to the French disruptions in opposite ways. The first was Edmund Burke's conservatism, which held that a society's customs were time-tested implementations of a civilizing process that had tamed humanity's dark side and as such deserved respect alongside the explicit formal propositions of intellectuals and reformers. Burkean conservatism, itself a fine application of reason, represented a small tweaking of Enlightenment humanism. But that ideal was blown to bits in Johann Gottfried von Herder's romantic nationalism, which held that an ethnic group -- in the case of Herder, the German Volk -- had unique qualities that could not be submerged into the supposed universality of humankind, and that were held together by ties of blood and soil rather than by a reasoned social contract.

The Congress of Vienna in 1815, when statesmen from the great powers engineered a system of international relations that would last a century, was a triumph of Burkean conservatism, aiming for stability above all else. Nonetheless, Howard observes, its architects "were as much the heirs of the Enlightenment as had been the French revolutionary leaders. They believed neither in the divine right of kings nor the divine authority of the church; but since church and king were necessary tools in the restoration and maintenance of the domestic order that the revolution had so rudely disturbed, their authority had everywhere to be restored and upheld." More important, "they no longer accepted war between major states as an ineluctable element in the international system. The events of the past twenty-five years had shown that it was too dangerous." The great powers took on the responsibility of preserving peace and order (which they pretty much equated), and their Concert of Europe was a forerunner of the League of Nations, the United Nations, and the European Union. This international Leviathan deserves much of the credit for the long intervals of peace in 19th-century Europe.

According to Howard, "this dialectic between Enlightenment and Counter-Enlightenment, between the individual and the tribe, was to pervade, and to a large extent shape, the history of Europe throughout the nineteenth century, and of the world the century after that." During those two centuries Burkean conservatism, Enlightenment liberalism, and romantic nationalism played off one another in shifting alliances (and sometimes became strange bedfellows).

But the stability was enforced by monarchs who ruled over lumpy amalgams of ethnic groups, which began to clamor for a say in how their affairs were run. The result was a nationalism that, according to Howard, was "based not so much on universal human rights as on the rights of nations to fight their way into existence and to defend themselves once they existed." Peace was not particularly desirable in the short term; it would come about "only when all nations were free. Meanwhile, [nations] claimed the right to use such force as was necessary to free themselves, by fighting precisely the wars of national liberation that the Vienna system had been set up to prevent."

Nationalist sentiments soon intermixed with every other political movement. Once nation-states emerged, they became the new establishment, which the conservatives strove to conserve. As monarchs became icons of their nations, conservatism and nationalism gradually merged. And among many intellectuals, romantic nationalism became entwined with the Hegelian doctrine that history was an inexorable dialectic of progress. As Luard summarized the doctrine, "All history represents the working out of some divine plan; war is the way that sovereign states, through which that plan manifested itself, must resolve their differences, leading to the emergence of superior states (such as the Prussian state), representing the fulfillment of the divine purpose." Eventually the doctrine spawned the messianic, militant, romantic nationalist movements of fascism and Nazism. A similar construction of history as an unstoppable dialectic of violent liberation, but with classes substituted for nations, became the foundation of 20th-century communism.

One might think that the liberal heirs of the British, American, and Kantian Enlightenment would have been opposed to the increasingly militant nationalism. But they found themselves in a pickle: they could hardly defend autocratic monarchies and empires. So liberalism signed on to nationalism in the guise of "self-determination of peoples," which has a vaguely democratic aroma. Unfortunately, the whiff of humanism emanating from that phrase depended on a fatal synecdoche. The term "nation" or "people" came to stand for the individual men, women, and children who made up that nation, and then the political leaders came to stand for the nation. A ruler, a flag, an army, a territory, a language, came to be cognitively equated with millions of fleshand-blood individuals. The liberal doctrine of self-determination of peoples was enshrined by Woodrow Wilson in a 1916 speech and became the basis for the world order after World War I. One of the people who immediately saw the inherent contradiction in the "self-determination of peoples' was Wilson's own secretary of state, Robert Lansing, who wrote in his diary:

The phrase is simply loaded with dynamite. It will raise hopes which can never be realized. It will, I fear, cost thousands of lives. In the end, it is bound to be discredited, to be called the dream of an idealist who failed to realize the danger until too late to check those who attempt to put the principle into force. What a calamity that the phrase was ever uttered! What misery it will cause! Think of the feelings of the author when he counts the dead who died because he uttered a phrase!

Lansing was wrong about one thing: the cost was not thousands of lives but tens of millions. One of the dangers of "self-determination" is that there is really no such thing as a "nation" in the sense of an ethnocultural group that coincides with a patch of real estate. Unlike features of a landscape like trees and mountains, people have feet. They move to places where the opportunities are best, and they soon invite their friends and relatives to join them. This demographic mixing turns the landscape into a fractal, with minorities inside minorities inside minorities. A government with sovereignty over a territory which claims to embody a "nation" will in fact fail to embody the interests of many of the individuals living within that territory, while taking a proprietary interest in individuals living in other territories. If utopia is a world in which political boundaries coincide with ethnic boundaries, leaders will be tempted to hasten it along with campaigns of ethnic cleansing and irredentism. Also, in the absence of liberal democracy and a robust commitment to human rights, the synecdoche in which a people is equated with its political ruler will turn any international confederation (such as the General Assembly of the United Nations) into a travesty. Tinpot dictators are welcomed into the family of nations and given carte blanche to starve, imprison, and murder their citizens.

The grandeur of war lies in the utter annihilation of puny man in the great conception of the State, and it brings out the full magnificence of the sacrifice of fellow-countrymen for one another… the love, the friendliness, and the strength of that mutual sentiment. -- Heinrich von Treitschke

War almost always enlarges the mind of a people and raises their character. -- Alexis de Tocqueville

[War is] life itself… We must eat and be eaten so that the world might live. It is only warlike nations which have prospered: a nation dies as soon as it disarms. --Émile Zola

Another development of the 19th century that would undo Europe's long interval of peace was romantic militarism: the doctrine that war itself was a salubrious activity, quite apart from its strategic goals. Among liberals and conservatives alike, the notion took hold that war called forth spiritual qualities of heroism, self-sacrifice, and manliness and was needed as a cleansing and invigorating therapy for the effeminacy and materialism of bourgeois society. Nowadays the idea that there could be something inherently admirable about an enterprise that is designed to kill people and destroy things seems barking mad. But in this era, writers gushed about it:

Wars are terrible, but necessary, for they save the State from social petrifaction and stagnation. -- Georg Wilhelm Friedrich Hegel

When I tell you that war is the foundation of all the arts, I mean also that it is the foundation of all the high virtues and faculties of man. -- John Ruskin

War is necessary for human progress. -- Igor Stravinsky

[War is] a purging and a liberation. -- Thomas Mann

Peace, in contrast, was "a dream and not a pleasant one at that," wrote the German military strategist Helmuth von Moltke; "without war, the world would wallow in materialism." Friedrich Nietzsche agreed: "It is mere illusion and pretty sentiment to expect much (even anything at all) from mankind if it forgets how to make war." According to the British historian J. A. Cramb, peace would mean "a world sunk in bovine content… a nightmare which shall be realized only when the ice has crept to the heart of the sun, and the stars, left black and trackless, start from their orbits."

Even thinkers who opposed war, such as Kant, Adam Smith, Ralph Waldo Emerson, Oliver Wendell Holmes, H. G. Wells, and William James, had nice things to say about it. The title of James's 1906 essay "The Moral Equivalent of War" referred not to something that was as bad as war but to something that would be as good as it. He began, to be sure, by satirizing the military romantic's view of war:

But then he conceded that "we must make new energies and hardihoods continue the manliness to which the military mind so faithfully clings. Martial virtues must be the enduring cement; intrepidity, contempt of softness, surrender of private interest, obedience to command, must still remain the rock upon which states are built." And so he proposed a program of compulsory national service in which "our gilded youths [would] be drafted off… to get the childishness knocked out of them" in coal mines, foundries, fishing vessels, and construction sites.

Romantic nationalism and romantic militarism fed off each other, particularly in Germany, which came late to the party of European states and felt that it deserved an empire too. In England and France, romantic militarism ensured that the prospect of war was not as terrifying as it should have been. On the contrary, Hillaire Belloc wrote, "How I long for the Great War! It will sweep Europe like a broom!" Paul Valéry felt the same way: "I almost desire a monstrous war." Even Sherlock Holmes got into the act; in 1914 Arthur Conan Doyle had him say, "It will be cold and bitter, Watson, and a good many of us may wither before its blast. But it's God's own wind none the less, and a cleaner, better, stronger land will lie in the sunshine when the storm has cleared." Metaphors proliferated: the sweeping broom, the bracing wind, the pruning shears, the cleansing storm, the purifying fire. Shortly before he joined the British navy, the poet Rupert Brooke wrote:

Its "horrors" are a cheap price to pay for rescue from the only alternative supposed, of a world of clerks and teachers, of co-education and zo-ophily, of "consumer's leagues' and "associated charities," of industrialism unlimited, and feminism unabashed. No scorn, no hardness, no valor any more! Fie upon such a cattleyard of a planet!

Now, God be thanked Who has matched us with His hour,

With hand made sure, clear eye, and sharpened power,

And caught our youth, and wakened us from sleeping,

To turn, as swimmers into cleanness leaping.

"Of course, the swimmers weren't leaping into clean water but wading into blood." So commented the critic Adam Gopnik in a 2004 review of seven new books that were still, almost a century later, trying to figure out exactly how World War I happened. The carnage was stupefying --8.5 million deaths in combat, and perhaps 15 million deaths overall, in just four years. Romantic militarism by itself cannot explain the orgy of slaughter. Writers had been glorifying war at least the since the 18th century, but the post-Napoleonic 19th had had two unprecedented stretches without a great power war. The war was a perfect storm of destructive currents, brought suddenly together by the iron dice of Mars: an ideological background of militarism and nationalism, a sudden contest of honor that threatened the credibility of each of the great powers, a Hobbesian trap that frightened leaders into attacking before they were attacked first, an overconfidence that deluded each of them into thinking that victory would come swiftly, military machines that could deliver massive quantities of men to a front that could mow them down as quickly as they arrived, and a game of attrition that locked the two sides into sinking exponentially greater costs into a ruinous situation -- all set off by a Serbian nationalist who had a lucky day.