For many years, German leaders had been struggling to cope with an influx of peoples across their borders. While the crisis was one that had afflicted much of Europe, it was Germany that bore the brunt. Year after year they had been coming, crossing from the steppes of the Carpathian Basin into Swabia and Bavaria, a relentless tide of migrants who, while they shared neither the religion nor the customs of the native Germans, were drawn by rumors of their wealth. Various policies had been attempted to stem the flow. Carrots, in the form of financial subsidies, and sticks, in the form of refurbished border controls, had been judiciously applied. Nothing, though, seemed to work. The determination of those beyond the limits of Germany to cross its frontiers appeared, if anything, to be stiffening. As a result, for the German authorities, the moment of truth was drawing near. The choice they faced was a stark one: solve the crisis, or lose control of their borders altogether.

The storm finally broke in the summer of 955. “A multitude of Hungarians, such as no living person can remember having seen in any one region before, invaded the realm of the Bavarians which they devastated and occupied simultaneously from the Danube to the dark forest on the rim of the mountains,” wrote Gerhard von Augsburg in his chronicle. It was not only the scale of the invasion force that filled the Germans with dread, though, but the evident scope of its preparations. Previously, when the Hungarians had raced out of their steppe-lands, they had done so exclusively on horseback, setting a premium on speed, the better to strip a landscape bare and retreat back to the ­Danube before the more heavily armored German cavalry could corner them. Plunder, not territorial acquisition, had been their goal. Now, it seemed they had a different strategy. Crossing into German territory, the horsemen rode at a measured pace. Alongside them marched huge columns of infantry. Siege engines creaked and rumbled in their train. This time the Hungarians had come to conquer.

Early in August, they arrived before the walls of Augsburg. The city, rich and strategically vital though it was, stood perilously exposed. Otto, the German king, had been campaigning far in the north, and no one knew when he might come to its relief. Ulrich, the city’s formidably learned bishop, took command. While men labored to shore up the walls, and women walked in procession, raising up fearful prayers, Ulrich toured the battlements, inspiring the garrison to trust in Christ. Yet so overwhelming were the forces besieging the city, and so menacing their preparations, that it seemed to many that ­Augsburg was bound to fall. On August 8, as siege engines crawled toward the fortifications and infantry were driven forward under the lash, a gateway above the river Lech was breached. Gerhard von Augsburg records that Ulrich, “wearing only his vestments, protected by neither shield, nor chain mail, nor helmet,” rode on his horse to block the Hungarians’ path. Miraculously, despite the hissing of arrows all around him, and the thudding of stones, he succeeded in holding the attackers at bay. The open gate was secured. The Hungarians did not enter Augsburg.

Relief for the imperiled city was on its way. Otto, informed of the invasion, rode south to confront it. With him he brought three thousand heavily armored cavalry and the single most potent treasure in his entire realm: the very spear which had pierced the side of Christ. Adorned as it was by the nails used in the Crucifixion, it served, as Liudprand of Cremona wrote, to “join the realm of the mortal to that of heaven.” In the terrible battle that followed, these advantages would prove sufficient to gain Otto a stunning victory. A great surging cavalry charge crushed the Hungarians; the German horsemen, pursuing them across the floodplain of the Lech, hacked and speared them; of the mighty force that had laid siege to Augsburg almost nothing was left. Such was the glory of Otto’s feat that his troops, standing on the battlefield amid the tangle of corpses and banners, hailed their triumphant king as “emperor.” Sure enough, within seven years, he was being crowned by the pope in Rome. The line of emperors that began with him would continue unbroken until 1806.

The battle of the Lech was decisive in another way, too. The Hungarians were merely the latest in a succession of nomadic peoples who, possessed of such speed as to seem barely human and the devilish ability to fire arrows even while on the gallop, had menaced the settled realms of Europe. Back in the fifth century, the onslaught of a steppe people named the Huns had overwhelmed the defenses of the Roman Empire and helped to precipitate the implosion of its entire western half. Now, by laying claim to the title of Caesar, Otto was declaring that the age of such invasions was past, that the frontiers of Christendom were stable, and that never again would the ululations of horse archers be permitted to chill the souls of decent Christians. A line had been drawn under the age of mass migrations. The Hungarians who had survived the killing fields of the Lech withdrew to the Carpathian Basin, there to lick their wounds and put down roots themselves. Fifty years on from the great battle, their chieftain, graced with the name of Stephen, was welcomed into the ranks of Christian kings. Sent a diadem by the pope, he was presented by Otto’s grandson with a replica of that most awesome of all the weapons in the possession of the German monarchy: the Holy Lance itself.

Elsewhere, too, Christendom was rallying against its foes. Both the Slavs, whom Otto had been fighting when first informed of the Hungarian invasion, and the pagans of Viking Scandinavia, who preyed on Britain, Ireland, and northern France, were increasingly being brought to Christ. Along the southern flank of Christendom, the enduring menace of Arab slavers, which had prompted one pope in the ninth century to lament that the whole of Italy was being “stripped bare of its inhabitants,” had likewise begun to be tamed. Not that the warriors charged with the securing of Christendom’s frontiers were content to confine themselves merely to defense. A hundred years on from the battle of the Lech, the tramping of their heavy war-horses was becoming a thing of dread to Muslim and pagan leaders alike.

Over the centuries that followed, a great wave of conquest, colonization, and evangelization reclaimed territory lost to Islam in southern Italy and Spain, and gained new land in Eastern Europe. Mosques were converted into churches; pagan shrines put to the torch. Nowhere else in Eurasia was there a civilization quite so religiously monocultural; nowhere else in Eurasia was there one quite so secure against the armies of mounted archers who tended otherwise to dominate the medieval battlefield. Even the Mongols, who in the thirteenth century put much of Eastern Europe in their shadow, failed to penetrate the heartlands of Latin Christendom. Only with the expansion of Ottoman power, which saw Muslim rule established over the Balkans and much of Hungary, did the civilization of Christian Europe face a serious menace from adversaries who did not subscribe to its own faith. After the failure in 1683 of a second Ottoman attempt to capture Vienna, it, too, ended in retreat. By the eighteenth century, with their fleets sweeping distant oceans, their flags fluttering over distant colonies, and their emigrants settling across the world, Europeans could take for granted the impregnability of their own continent. Mass migration, it had come to be assumed, was something that they inflicted upon the lands of non-Europeans—not the other way round.

The lethal talent displayed by Europeans for war and empire building in the world beyond did not preclude them from unleashing it against one another as well. The same Normans who wrested Sicily from Muslim rule had only a few years earlier conquered the thoroughly Christian kingdom of England. Otto, despite the greatness of his achievements and the splendor of his coronation, had failed to mold his empire into a new Rome. The dream of a pan-European imperium, far from joining the peoples of the continent within a single political order, perpetuated the hatreds and rivalries that divided them. The termination in 1806 of the line of emperors founded by Otto the Great came amid the convulsions of Napoleon’s own attempt to found a great empire. Despite the astonishing sweep of his conquests, he ultimately left Europe more riven than ever. In 1870, and then again in 1914, hostility between France and Germany exploded into war. The second conflict engulfed Europe in a war more ruinous and terrible than any in its history.

“For a moment the water below him looked like some window, glazed with grimy glass, through which he was peering. Wrenching his hands out of the bog, he sprang back with a cry. ‘There are dead things, dead faces in the water,’ he said with horror. ‘Dead faces!’” This terrifying vision, of corpses drowned in the mud of a battlefield, and left to float for all eternity, appeared in the novel that has probably done more to define a particular vision of European history than any other published in the last century. Its author, who had joined the British army in 1915 and fought in the Battle of the Somme, was one of many writers and artists who sought to make sense of the calamity that had engulfed Europe.

That horrors conjured up from both the distant past and the age of fascism should merge in The Lord of the Rings makes it no less a product of Europe’s mid-century agony than are, say, Guernica or Doctor Faustus. What did render Tolkien exceptional, though—and indeed, perhaps, the last of a kind—was the degree to which he took literally notions that were already venerable in the age of Otto the Great. Tolkien, devout Catholic that he was, believed in evil, not as an allegory or as a metaphor, but as something literal: a satanic force. The character of his faith was of a kind that Bishop Ulrich of Augsburg might have recognized: one that took literally the intervention of angels in human affairs, the legitimacy of sacral kingship, and the potency of sanctified weapons. The Return of the King, Tolkien titled the last volume of The Lord of the Rings; and when Aragorn, claimant to the throne of Minas Tirith, appears before the walls of the city at the head of a great host, and leads the slaughter of those besieging it, he is armed—just as Otto had been at the battle of the Lech—with a token of his supernatural mandate. “But before all,” Tolkien writes, “went Aragorn with the Flame of the West, Andúril like a new fire kindled, Narsil re-forged as deadly as of old.” The ideal is that of the Christian warrior, dressed in the armor of God’s favor. Sure enough, when Sauron is finally overthrown, and Aragorn’s return as king thereby rendered certain, Tolkien makes clear the theological context for this dramatic climax. The fall of Mordor occurs on the twenty-fifth of March: the very date on which, back in the age of Otto the Great, it was conventionally believed that Christ had been crucified.

Such theological subtleties, it is true, have rarely been noted by the millions around the globe who have helped to make The Lord of the Rings the single bestselling European novel of the past century. Though it sprang from Tolkien’s incomparable knowledge of the languages, literature, and history of early medieval Europe, it requires no specialist knowledge to be enjoyed. As a result, and by an irony that would doubtless have appalled Tolkien, it has inspired a repackaging of the culture of the early Middle Ages in a form that has been largely drained of historical specificities. Magical weapons and warlocks with staffs have become the common currency of an entire new global genre. The very word used to describe it, “fantasy,” suggests how much it has been severed from the moorings so treasured by Tolkien. When Peter Jackson, a New Zealander working for an American studio, made a three-part film adaptation of The Lord of the Rings, its massive global success demonstrated just how universal was the appeal of narratives garbed in the armor and samite of Europe’s medieval past; but it demonstrated as well just how deracinated even those directly inspired by Tolkien had become.

It is hardly surprising, in a continent that has witnessed as many social and ideological upheavals as Europe has over the past millennium, that the world of Otto the Great should now appear as fantastical as that of Aragorn. We are separated from the ideals and convictions that inspired him at the battle of the Lech by the Reformation and the Enlightenment, and by both the French and the Industrial Revolutions. Nothing has done more to prevent Europeans—and Germans in particular—from eulogizing the martial exploits of Otto and his ilk than the calamitous events of the past century. In 1946, even as Tolkien was writing his account of the siege of Minas Tirith, the trial opened in Nuremberg of the most prominent surviving members of the Nazi leadership. A year on from the liberation of Bergen-Belsen and Auschwitz, details of the proceedings made clear to the world the full genocidal scale of the Third Reich’s crimes.

The image of the First Reich, founded by Otto the Great in the wake of the battle of the Lech, could not help but be contaminated by the uses to which Nazi propagandists had put it. Himmler had enshrined Otto’s father, a warrior-king named Heinrich, as the supreme model of Germanic heroism, and was darkly rumored to have believed himself the king’s reincarnation. Hitler, although privately contemptuous of Himmler’s more mystical leanings, had himself been obsessed by Wagner’s opera Parsifal, which gave a prominent role to the Holy Lance. The wellsprings of German history could hardly have been more poisoned. The warrior traditions of the First Reich, which had long provided Germans with a source of patriotic pride, were utterly tarnished. Only if recast as fantasy could their glamor be enjoyed. In the mythology of postwar Europe, it is no longer the kings of the First Reich who are associated with the Holy Lance, but Hitler.

The guilt, though, was not the Germans’ alone. “To write poetry after Auschwitz,” Theodor Adorno famously wrote, “is barbarism.” It was the history and culture of Europe as a whole that had led to the Holocaust, and so it was the history and culture of Europe as a whole that stood on trial. European self-loathing was compounded by two further developments: the collapse of the British, French, and Dutch empires, and the arrival in Western Europe of large numbers of immigrants from non-European countries. Britain’s painting the globe red and France’s mission civilisatrice were transformed in the course of only a couple of generations from causes for national self-congratulation to embarrassments. As Western Europe—for the first time since the expulsion of Spain’s Moors in 1492—came to play host to large numbers of Muslims, the history of the West’s interactions with Islam provided scope for particular revisionism. The involvement of numerous European countries in the U.S.-led invasion of Iraq in 2003 was placed firmly and understandably by its critics in the context of two centuries of British and French weight-throwing in the Muslim world. The Reconquista, long celebrated by Spaniards as the redemption of the country from alien conquerors, was recast as the destruction of an oasis of sophistication and tolerance, in which Jews, Christians, and Muslims had all happily sat next to tinkling fountains, snacking on oranges and discussing Aristotle. National heroes such as Godfroi de Bouillon, Richard the Lionheart, and Don John of Austria were all quietly retired, and “crusader” rendered a dirty word.

The assumption that the conflict between medieval Christendom and its Arab and Turkish adversaries was merely an expression of inveterate European racism, rather than what it truly was—a desperate, see-sawing struggle for survival—was enshrined as a new orthodoxy. Elites who had once delighted in proclaiming the supremacy of their own culture now pat themselves on the back for scorning it. A continent that had come to pride itself on transcending history had no wish to dwell on the more embarrassing aspects of its own past. In 2003, when the first draft of a putative E.U. constitution was drawn up, its authors were happy to acknowledge Europe’s debt to ancient Greece and Rome, and to salute the achievements of the Enlightenment—but of the Christian roots of European civilization not a mention was made. The implication was obvious: Everything between Marcus Aurelius and Voltaire ranked as backwardness and superstition. Europe’s values had to be reckoned not sectarian, but universal—or they were nothing.

That the European Union owed nothing to Christianity would, of course, have come as news to men like Konrad Adenauer or Robert Schuman: founding fathers of the European project who were at the same time devoutly Catholic. Even today, with pews across Europe increasingly empty, the attempt to fashion an inclusive and multi-faith future for the continent remains shadowed by a paradox: that it has patently been grounded in Christian doctrines. The inheritance of Christendom, even when most assertively repudiated, has proven a hard one to buck. The Bible, for all that it might be deployed to mandate the violence of warrior-kings and crusaders, was not only a tool of the mighty. It served as well to endow the weak, the poor, and the needy with a value that they had never before possessed. “You have heard that it was said, ‘You shall love your neighbor and hate your enemy.’ But I say to you, ‘Love your enemies . . .’” Such a command, like many that Jesus gave, might seem so counterintuitive as to appear impossible to fulfill; and yet for all that, and however little many may have paused to contemplate its ultimate derivation, it has provided elites across Europe, in their efforts to accommodate immigrants from outside the Christian tradition, with their moral lodestar. In the wake of Nazism, no text has done more to underpin the construction of a new and multicultural identity for the continent than the Sermon on the Mount. It is not enough for Europeans to tolerate different cultures: They must learn to respect and embrace them as well. “We don’t have too much Islam,” as German Chancellor Angela Merkel put it, “we have too little Christianity.”

A striking suggestion for Europe’s most powerful leader to float. Merkel made it as she sought to win her party’s support for her policy toward the thousands of migrants and refugees from Muslim countries who, over the course of the summer, had been moving through the Balkans and into Hungary. Merkel had not summoned the heavy cavalry; she had not played at being Otto the Great. Instead, on September 4, she opened up Germany’s borders. Syrians, Afghans, and Pakistanis immediately began crossing into Bavaria. Soon, upwards of 10,000 a day were entering Germany. Crowds gathered at railway stations to cheer them; football fans raised banners at matches to proclaim them welcome. The scenes, Merkel declared, “painted a picture of Germany which can make us proud of our country.” The exorcism of the Nazi years appeared complete. Yet Merkel, although painfully conscious of the shadow cast by her country’s history, was inspired as well by her upbringing as the daughter of a pastor and of a mother no less devout. Rainer Eppelmann, an old political associate of the chancellor’s, and a pastor himself, has emphasized the influence on her as a girl of the Sermon on the Mount. “The daily message was: Love thy neighbor as yourself. Not just German people. God loves everybody.”

Yet, inevitably, not all Merkel’s compatriots have been enthusiasts for her open-door policy, or her acknowledgment that a huge influx of people from very different cultures to that of Germany will inevitably change the country. “That is then a different society.” So the Bavarian leader, Horst Seehofer, has complained. “People don’t want Germany or Bavaria to become a different society.” The irony that German Christians who do their duty toward Muslim refugees may thereby be expediting an eclipse of Europe’s Christian character has not gone unnoted. By a further irony, the man who has pointed this out most intemperately, and thereby invoked something of the martial spirit of Otto the Great, is none other than Prime Minister of Hungary Viktor Orbán. That Orbán himself was until recently a self-avowed atheist has not prevented him from publicly doubting—much as Otto might have done over a millennium ago—whether unbaptized migrants can ever truly be integrated. “That is an important question, because Europe and European culture have Christian roots,” he argues. In countries like Orbán’s, where folk memories of the Ottoman occupation remain strong, and Poland, where the population’s religious complexion retains something of Christendom’s old homogeneity, Muslim immigrants are now openly described by government ministers as a menace. In Germany, too, where street campaigns against “the islamization of the Occident” have swelled over recent months, and in the ranks of nationalist parties from Finland to France, and in angry chatrooms, and on websites much adorned with images of ­magical swords, there is no lack of people to play the role of Tolkien’s Denethor, and warn, “All the East is moving.”

The abiding potency of such a dread, bred as it is of the marrow of European culture, is hardly surprising. If the imagery of knights manning the battlements of a beleaguered city against orcs can be used to sell video games, then why not a political narrative? It is, after all, a multi-player edition. Europeans were not the only ones in the Middle Ages to sacralize violence. The Muslim forces who, shortly after the death of Otto the Great, sacked the Cathedral of Santiago de Compostela in northern Spain and harvested the heads of its defenders were no less convinced of their divinely authored mandate than was Bishop Ulrich as he stood in the breached gate of Augsburg. Muslim corsairs, as they descended on an unsuspecting Italian town, would hunt out slaves in the certainty that they were licensed to do so by God. To Muhammad, and to all who followed him, had been granted the “spoils of war”—and a constituent part of this plunder was human livestock.

So Muslims tended to believe back in the tenth century. That most no longer believe it today demonstrates the degree to which ethical standards in Islam, as in Christianity, have evolved over the centuries. Yet just as the Norwegian mass murderer Anders Breivik, when he denounced Labour party members as representatives of a “multiculturalist regime” deserving of execution, invoked the Knights Templar to justify his rampage, so are there Muslims living in Europe now convinced that decapitations and slavery can readily be justified by the example of Muhammad. “We estimate,” declared the E.U. commissioner for justice last spring, “that 5,000 to 6,000 individuals have left for Syria”—there to join an organization that openly exults in the beheading of prisoners and the enslavement of “pagans.” The past, it turns out, is a nightmare from which Europeans have not woken up, after all.

The conceit that secular liberal democracy embodies an ideal that can transcend its origins in the specific cultural and religious traditions of Europe, and lay claim to a universal legitimacy, is one that has served the continent well. It has helped to heal the grievous wounds inflicted by the calamities of the first half of the twentieth century; to integrate large numbers of people from beyond the borders of Europe; and to provide a degree of equality for women and minorities. What do the sanguinary fantasies of either Breivik or of the jihadists who twice in 2015 brought carnage to the streets of Paris have that can compare? Only one thing, perhaps: a capacity to excite those who find the pieties of Europe’s liberal society boring. The more of these there are, the more—inevitably—the framework for behavior and governance that has prevailed in Western Europe since the end of the Second World War will come under strain. In question is whether the large numbers of migrants who have no familiarity with the norms of a secular and liberal society such as have evolved in a country like Germany will find them appealing enough to adopt; and whether native Europeans, confronted by a vast influx of people from a different cultural background, will themselves be tempted to abandon liberal values, and reach for a Holy Lance.

Otto the Great, despite the brutality with which he trampled down the Hungarians on the plain of the Lech, never doubted that migrants from beyond the limits of Christendom could be integrated into his realm. Baptism offered any pagans who wished to take their place among the ranks of the Christian people a ready entry visa. The defeated Hungarians were not alone in accepting it. In France and England, so did Viking chieftains cornered by their adversaries, and offered lands if they would only bow their necks to Christ. The forefathers of those same Normans who conquered Sicily back from Islam had been worshippers of Odin. Today, though, in a Europe that has ceased to be Christendom, no ritual comparable to baptism exists—nor could possibly exist. The nearest equivalents may be the classes given in Norway to refugees about the principle of sexual consent, or the cards issued by the Austrian government to migrants advising them that it is perfectly permissible for two men to kiss. Whether these rituals will inspire new arrivals to do as the Hungarians and Vikings did, and abandon the convictions and conventions of their homelands, only time will tell. If ideas of freedom and tolerance fail to gain universal acceptance, it may once again become necessary to acknowledge explicitly the Christian faith that was their wellspring and may yet prove to be their mainstay.

Tom Holland is author, most recently, of Dynasty: The Rise and Fall of the House of Caesar.

