A brief golden age: Trajan, Hadrian and Antoninus Pius, AD 98–161

After the crisis of AD 66–70, it had been hoped that the Flavian victory might herald another century of peace and security like that after Actium. Rebels, mutineers and civil-war factions had been crushed, and, during the 70s AD, with order and discipline restored under strong rulers, the army pushed forwards again on the frontiers – in Britain, in Germany, in the East. Then things seemed to unravel in the mid-80s. The Dacians had invaded Roman territory and defeated Roman armies. Domitian had punished them, but left them unbroken, a great kingdom just over the Danube, a skulking menace in the vastness of the Carpathians. Instead of settling with Decebalus, he had been provoked by plotters into turning on his own people, and blood had flowed among the rulers of Rome in the 90s. From great victories to punitive raids and civil strife: the later years of Flavian rule seemed to follow a depressing, downward trajectory. Was Roman power waning?

Two of Rome’s greatest emperors, ruling in succession, Trajan (AD 98– 117) and Hadrian (AD 117–138), offered radically different solutions to the crisis of empire in the early 2^nd century. The contrast reveals the uncertainty of an imperial ruling class past its peak: the uncertainty that occurs when unexpected weakness is exposed and the attempt to continue in the old way falters. The history, traditions and values of Old Rome denied this possibility: was it not the divinely ordained destiny of the race of Romulus to rule the world, ‘to command the nations, to impose peace, to spare the submissive, to crush the proud’? Yet a different image of the future had intruded, one in which shadowy forms of barbarian hordes and insurgent masses appeared in the frame. Perhaps the priority was to stiffen the empire’s defences, and to foster the loyalty, unity and commitment of those standing behind them; to draw a line across the world, ‘separating Romans and barbarians’, them and us, rallying all the human and material forces of the empire in the cause of civilization. To continue to conquer in the old way, or to build a new commonwealth of peoples: this was the choice represented, respectively, by Trajan and Hadrian.

Trajan’s immediate predecessor, the emperor Nerva (AD 96–98), had been an old man of little account. Representing no one in particular, he had had no particular mission to perform. He had been an historical dud, a convenient fill-in while the Roman governing elite recovered its nerve and found a way forwards. Once they had, Nerva obligingly died. By then, his regime was tottering, propped up at the last minute by one of the few wise decisions he made: naming Marcus Ulpius Traianus his successor. Trajan was a true soldier-emperor. An experienced and successful career officer, he was, at the time of his accession, serving as Governor of Upper Germany, making him one of Rome’s top generals and a man rooted in one of its three major army-groups. Though of Romano-Spanish origin, his family was already established in the Senate, so, if he was a soldiers’ candidate, he was equally acceptable to the politicians. Having named this popular successor, Nerva could be left to die peacefully, which he did just a month or two later. Trajan, still in Germany, was immediately hailed emperor without opposition.

Like Tiberius or Vespasian – but unlike Caligula or Domitian – Trajan did not have to prove his fitness to rule, and happily dispensed with the flummery of power that lesser men found necessary. His court was simple, the etiquette minimal, his person approachable, straight-talking, on the level. In this respect he was a Roman of the old school. So, too, in other, more important respects: for Trajan was, above all, a general and a conqueror.

Strangely – for he is one of Rome’s greatest emperors – our written sources for his reign are poor. Our principal source for his two great campaigns of conquest in Dacia is his own victory monument – Trajan’s Column, which still stands in the centre of Rome, its outer surface adorned with a spiralling ribbon of carved stone, just under a metre wide, some 200 m in length, depicting more than 2,500 separate figures engaged in the successive stages of war. It is, of course, a tainted source. It depicts only Dacians dead and dying, never Romans, and we can guess that much else about the imagery is selective. Yet, close reading of the ribbon, of one image following another – supplemented by fragments of evidence from elsewhere – allows a tentative reconstruction of events in Dacia in AD 101–102 and 105–106.

A force of perhaps 100,000 men was involved. Their supply was a logistical challenge of the highest order. The key was to use the Danube to ship grain from the Black Sea, but the rapids at the Iron Gates were an insuperable barrier to up-river navigation until Trajan’s engineers cut a canal to bypass the worst, and restored a towpath that was part-carved into the cliff-face and part-projecting on a cantilevered timber frame. Then troops, transports and equipment were concentrated, new store-bases, forts and signal-stations constructed. Finally, the army crossed on pontoon bridges, the legionaries wearing new reinforced helmets and arm-guards, amply supplied with high-tech artillery, and supported by numerous auxiliaries, including archers, slingers and armoured cavalry.

But Decebalus was a cunning old fighter. He withdrew deep into his mountains, burning the ground behind him, until he reached Tapae, where, posting his warriors on the slopes above the pass, soon turned into slides of mud by torrential rain, he held shut the gates of Dacia. The following year, Trajan attacked again, this time in two columns, one to hold the enemy at Tapae, the other to force a way through by a second route, outflanking the main Dacian defence. The Column shows the native hill-forts on the approach reduced one by one – testimony to the fort-busting power of Roman siege-assaults – as the protective shell around Decebalus’s capital at Sarmizegethusa was cracked open. Then, at the eleventh hour, Decebalus sued for peace. He saved his kingdom from annexation, but it was reduced to client status, and he was compelled to demolish his remaining hill-forts and accept a Roman garrison at his capital. Presumably the Dacian resistance had been strong enough to prevent outright victory, the capital perhaps just beyond Trajan’s grasp at the end of a second summer.

Three years later, Decebalus felt strong enough to break free. He first took the commander of the Roman garrison at Sarmizegethusa hostage. But the general, an old friend of Trajan, killed himself to leave the emperor free to act. Again, two columns invaded, moving fast, reducing hill-forts in rapid succession, fighting with greater brutality than ever against men now deemed rebels. This time the Dacian capital was besieged and captured, though the king fled into the mountains, hotly pursued by Roman cavalry. The images on the Column are graphic: we see the king on the ground, isolated, surrounded, knife poised to take his own life, as so many of his followers had already done; meantime, towns and villages are torched, fugitives cut down, captives rounded up and dragged into slavery; and then an image of the dead king’s head, held aloft before Trajan’s assembled army.

In 1965, in a field in northern Greece, the tombstone of a Roman soldier was found: it was that of the man who had captured Decebalus and carried his severed head to Trajan. It read: ‘He was made a duplicarius [junior NCO] by the divine Trajan in the Second Pannonian Cavalry, and then an explorator [scout]. He was decorated twice in Trajan’s Dacian and Parthian wars. He was promoted to decurio [senior NCO] in the same cavalry regiment because he captured Decebalus and brought his head to Trajan at Rannistorum. He was honourably discharged by Terentius Scaurianus.’(13) This, of course, was the ultimate victory: the enemy dispersed; his capital taken; his leader slain; his territory plundered, laid waste, stripped of men. Dacia was ethnically cleansed, its people enslaved, at least 50,000 of them, though possibly, if there is no error in transmission of the written source, as many as 500,000; others, no doubt, were driven into the wilderness, where they perished. New settlers were introduced, and a new Roman province built, with roads, towns, pastures, salt-works and gold-mines.

The conquest of Dacia was celebrated in the old-fashioned way. A corrupted written source records the haul as 2.25 million kg of gold, 4.5 million kg of silver, and 500,000 slaves. Assume a simple transmission error and we might reduce these astronomical figures to a tenth of the size; even then, they represent, at the equivalent of around 675 million denarii, more than the whole sum of disbursements recorded by Augustus in the Res Gestae. We see something of this booty still preserved in surviving monuments of stone. A new commercial harbour, nearly one kilometre across, with berthing for 100 ships, ringed by great warehouses, was built at Portus near the Tiber mouth: a guarantee of the city’s grain-supply. A massive public bath-house was erected, no doubt with deliberate symbolic intent, on the ruins of Nero’s Golden House on the Esquiline Hill. Ancient slums were cleared in the zone immediately north of the Forum, and a great chunk of the Quirinal Hill, to a maximum depth of 38 m, was cut away, creating a wide open space, 200 m by 120 m, for the greatest of Trajan’s buildings. The space was filled by a new imperial forum and basilica, the latter 80 m long by 25 m wide and lavishly decorated with imported marble columns. Beyond the basilica, on the western side of the complex, was a pair of libraries, and these framed the famous Column, allowing visitors to the library a close view of the sculpted scenes of the emperor’s Dacian wars. Behind the imperial forum, resting against the cut-away hill to the north, a multi-storey complex of vaulted passageways, arcaded shops and luxury flats was built. Trajan’s Markets still survive as the best place in the modern city to get a sense of what it was like to walk the streets of ancient Rome. There was a message in all of this. Trajan’s answer to the crisis of empire was the familiar one: war is glorious, and it is conquest that yields security and riches. The empire was not weakening: Rome was still an earth-shaking colossus striding the globe.

But the richest rewards, as always, glittered beyond the haze of the eastern deserts. Here, the Flavian policy of border annexations had brought the legions up to the Parthian frontier. Then Trajan had ordered the annexation of Nabataean Arabia (centred on the great caravan city of Petra) in AD 105–108. Soon a new road was being built, linking Syria with Petra, Aqaba and the Red Sea. Tension mounted. In AD 110, Osroes succeeded to the throne of Parthia, a king committed to aggressive defence. The pro-Roman puppet ruler of Armenia was ejected and replaced by a kinsman of the Parthian king. Trajan, no less aggressive than Osroes, champion of traditional imperialism, victor over Decebalus, set himself the ultimate challenge: a great war of conquest in the East to eliminate the Parthian threat forever. Concentrating massive force – eight legions plus supporting auxiliaries (80,000 men) – he unleashed a military blitzkrieg in AD 114, overrunning Armenia, descending into northern Mesopotamia, sweeping up hasty declarations of allegiance from the Parthian client-kings in his path. The following year, his army raised to 13 legions (130,000 men), he pushed on south, down the lower Tigris and Euphrates, finally to reach the Gulf, the whole of Mesopotamia under his control. It was a dizzying achievement. The Land of Two Rivers was among the oldest, richest and most heavily populated centres of civilization in the world. It had been the supply-base of numerous great empires over millennia of time, but no Roman – not Sulla, Crassus, Pompey, Caesar, Antony or Octavian-Augustus – had ever come nearly so far. That winter of AD 115/116, Trajan appeared greater than them all: a new Alexander.

But Alexander had fought two great battles of annihilation against the armies of the Persian Empire before he marched on Babylon. His enemies’ military power had been broken before he took their capital cities. Trajan’s achievement was puny by comparison. He had not yet faced the Parthian army at all – that enemy was still very much at large. His communications stretched back over hundreds of miles of river, desert and mountain. Vast populations were held in thrall by relative handfuls of soldiers. The Roman defence-line was wafer-thin. In the vast expanses of the East, the social and military weight of eastern humanity threatened to swamp the scattered pockets of Roman officials and soldiers among them. And so it came to pass. In AD 116, the Parthian Empire struck back. The main royal army, mustered on the Iranian plateau, swept down the passes of the Zagros Mountains, assailed the Roman supply-line, and crushed the battle groups sent against them. The ancient cities of Mesopotamia exploded into revolt: Roman garrisons were massacred, and Trajan was soon embroiled in a war of sieges to hold and retake key strategic centres. Meantime, deep in the Roman rear, a revolt among the Jews of Cyrene quickly spread to Jewish communities in Egypt, Cyprus and eventually Palestine itself. Finally, gut-wrenching news filtered through to the embattled army commanders in Mesopotamia that there was trouble in Britain and on the Danube: frontiers stripped of men for Trajan’s eastern war were now exposed to attack as enemies learned that the army was bogged down. Trajan headed for home, leaving Hadrian, his principal lieutenant, in charge in the East. But on the way, in August AD 117, he fell ill and died. And, with the whole East in flames, his attempt to resolve the crisis of imperial overstretch by a return to untrammelled expansionism had died with him. Roman imperialism had lurched forwards, kangarooed and crashed.

The roots of Trajan’s failure were deep. Ancient military imperialism was dynamically expansionist because it paid for itself and yielded a profit: it generated in plunder and tribute more than it cost. If this had not been so, it would have ruined the states that engaged in aggressive war, and impoverished their ruling classes – in which case there would have been neither the incentive nor capacity to wage it. Quite simply, war and empire were profitable. But only up to a point.

Everything depended on whether the land fought over could yield a return. Empire and civilization were based, broadly, on plough agriculture. Regions of intensive cultivation, supporting large populations and numerous settlements, produced surpluses that could be expropriated as booty, taxes, rents, tithes, interest and labour services. But the lower the level of agricultural development, the more marginal the potential gains. Beyond the plough-lands, in the marshes, forests, mountains and deserts of truebarbaricum, regions populated sparsely by nomads, pastoralists and scattered crofters, there was little portable wealth. Here, moreover, armies could be swallowed up in great tracts of uncharted wilderness, starving at the end of long, fragile supply-lines, harassed by elusive guerrilla bands, bogged down in unwinnable and pointless wars. Heavy investment in men and hardware might count for little in such environments, even be liabilities. War and empire in the wilderness were not profitable, for there was little profit to be had; they were merely a drain on the plough-lands of the hinterland required to support the effort of conquest. Everywhere, the Roman Empire reached its natural limits where the ploughed met the unploughed, ancient agriculture bordered primitive wasteland, civilization confronted barbarism – in the mountain ranges of north-west Africa, at the desert fringes of Libya, Egypt, Palestine and Syria, along the Danube and in the Rhineland of continental Europe, and in the hill-country of northern Britain.

Almost everywhere: the exception was the narrow border with Parthia. Here, in contrast, the enemy was a rival empire, another super-power based on plough-agriculture. Rome and Parthia confronted one another in a corridor of cultivated land which ran north-west to southeast along the river lines of the upper Tigris and Euphrates. Invasions on this route were hedged with hazard. Elsewhere, on every other frontier, Rome now held the outer line of the plough-lands, and her army was stretched thin along it, often dangerously so. Yet to mount an invasion of Parthia, she had to mass great forces, for the strength of any army was sapped with each march forwards, by attrition in the field, and by the guards and garrisons that had to be left in the rear. Parthia’s vast spaces, the great distance to her heartlands, the invincibility of her armoured cavalry and horse-archers on the open steppe, these things made a Roman conquest of the Orient a supreme military challenge. Repeatedly, since Crassus at Carrhae in 53 BC, the limits of Roman imperial power had been tested against the Parthian Empire, and each time they had been reached far short of any final victory. Rome was at an impasse on the eastern front: though able to contain it, she lacked the means to overthrow the Parthian Empire. Trajan had tried harder than any of his predecessors: his failure in consequence was more complete.

Publius Aelius Hadrianus, like Trajan, was Romano-Spanish. The two men were, in fact, related, and after Hadrian’s father had died when the boy was ten, he had been entrusted to Trajan’s care. Much later, he was married to Trajan’s great-niece, Sabina, a loveless marriage without affection or issue, but one convenient in fixing Hadrian’s position at the centre of his patron’s network. Close family ties made Hadrian trustworthy, but he was also intelligent, well educated and energetic, a man suited to high responsibility. By the time of his elevation in AD 117, he was already a veteran general, having served in all three of Trajan’s wars – as a staff officer in the Second Dacian War, a legionary commander in the Third, and, successively, as Governor of Syria and then commander-in-chief during the Parthian War. Even so, the accession was murky and contested. Nor is it difficult to guess what issue lay at the heart of the bloody clash at the top that inaugurated Hadrian’s principate.

The written sources for Hadrian’s reign are little better than those for Trajan’s, and we have few details of the generals’ plot of AD 117. Before reaching his capital, Hadrian’s Praetorian Prefect had arrested, condemned and executed four of Trajan’s leading marshals, charged with plotting against the new emperor. Probably, with some reason, they had argued that Hadrian was neither the appointed successor, nor an appropriate candidate. Trajan’s death had been sudden. No heir had been publicly announced – perhaps for fear of igniting animosities among the army commanders. But Hadrian was the late emperor’s ward, favourite, nephew by marriage, and commander-in-chief in the East, so perhaps his inheritance was implicit. The formal announcement, however, and the passing on of the imperial signet-ring had been a death-bed scene witnessed only by Trajan’s wife, Hadrian’s mother-in-law, the Praetorian Prefect, and a personal servant of the emperor – who, suspiciously, died suddenly soon after the event. The succession document bore his wife’s, not Trajan’s, signature. Was Hadrian, perhaps, a usurper? The new emperor was certainly at pains to win approval. He spent almost a month among the soldiers before arriving in the capital, determined first to show his face to the frontier legions and collect their acclamations. Then, a shower of largesse: large donatives were paid to the soldiers and the city mob; ‘coronation gold’, a tax traditionally paid at the accession of a new emperor, was remitted for Italy and reduced in the provinces; and all debts to the state were cancelled, at the spectacular cost of 225 million denarii.

The root of both the plotters’ malevolence and the emperor’s anxiety lay, almost certainly, in a deep split within the army command about the military débâcle in the East and the future direction of the empire. For Hadrian had resolved to pull out and consolidate. More than that: to stamp this policy on the empire forever. The contrast between the politics of Trajan and those of his protégé could not have been more radically different. Two men, both reared in the same stable, the one the pampered favourite and intimate of the other, reached diametrically opposed conclusions about how the empire should be governed. And while both were ideologically driven, Trajan’s vision was a reactionary one, an attempt to return to the glory days of war and conquest, whereas Hadrian was a radical trying to make sense of new realities and fashion a new model empire. It was perhaps crucial that he was a provincial emperor. Reared in Spain, he had travelled during his career in Gaul, Germany, the Balkans, Asia Minor, the Levant and Mesopotamia. Italy, for him, was just one among the many provinces of the empire. He was the first emperor for whom the traditional imperial title pater patriae (father of his country) – which, like his model, Augustus, he adopted only at the end of his reign – meant not merely protector and patron of Rome and Italy, but of all the provinces of the empire. He wished to raise all to the same level of peace, prosperity, good governance, urban life and classical culture; to create a commonwealth of peoples enjoying the benefits of thePax Romana and united by their allegiance to emperor, empire and Roman values. Thus would the empire grow stronger within. Thus would its people more willingly shoulder the burden of defence. Thus would the frontiers – now better defined, fortified and garrisoned – more easily be held. Hadrian set out to create a dichotomous world, in which the difference between civilization and barbarism was to be made sharper, the boundaries between them more rigid and immutable. It was a vision and a policy for an empire that had reached its limits.

Hadrian spent much of his reign travelling. But while his predecessors had sometimes done this in order to make war, Hadrian travelled in order to govern. The restless energy of the top commander that he had been became that of the visionary statesman, the nation-builder, the modernizing reformer, determined to see everything for himself, to make assessments on the spot, and to set in train the great projects needed to remake the world. He first toured the western provinces – the Rhineland, Britain, Gaul, Spain and Mauretania (Morocco) – in AD 120–123. Then he visited the Greek cities of Asia Minor, Old Greece and Sicily in AD 124–126. After two years in Rome, his third trip took him to Africa in AD 128. His fourth, in AD 129–131, was again to the East, to revisit Athens, and then on to Antioch, to Palmyra and Damascus, to Jerash and Petra, to Jerusalem, to Alexandria in Egypt and Cyrene in Libya.

Everywhere he went the emperor seems to have left an indelible mark: the archaeology of the Roman Empire still bears, on the frontiers and in the great classical cities, the imprint of Hadrian the Builder. He had made himself known already to the legions in the East and on the Danube, so in the early years of his reign he visited the men stationed on the Rhine, in Britain and in North Africa. Over some ten years Hadrian completed a great tour of inspection of the entire army and frontier system. ‘He personally viewed and investigated absolutely everything,’ explained Dio Cassius, ‘not merely the usual installations of the camps, such as weapons, engines, trenches, ramparts and palisades, but also the private affairs of everyone, both of the men serving in the ranks and of the officers themselves – their lives, their quarters, their habits – and he reformed and corrected in many cases practices and arrangements for living that had become too luxurious. He drilled the men for every kind of battle, honouring some and reproving others, and he taught them all what should be done.’(14) The praises of the commander-in-chief, witness to a military tattoo at Lambaesis legionary fortress in North Africa, were proudly recorded on the base of a stone column: ‘You did everything in orderly fashion. You filled the field with manoeuvres. Your javelin hurling was not without grace, although you use javelins which are short and stiff. Several of you hurled your lances equally well. And your mounting was smart just now and lively yesterday. If there was anything lacking, I should notice it; if there were anything conspicuously bad, I should point it out. But you pleased me uniformly throughout the whole exercise. My legate Catullinus, vir clarissimus, devotes equal care to all the branches he commands … Your prefect evidently looks after you carefully. I bestow upon you a largesse …’(15)

But it is the frontier defences that most visibly record the emperor’s passing. Open lines controlled by forts, signal-stations and patrols were replaced by continuous linear barriers formed of ditches, palisades and walls. Hadrian’s Wall in Britain is the supreme and best-studied example. Extending 73 miles (117 km) from Newcastle to Carlisle, it comprised a stone wall up to 3 m thick and perhaps 4.5 m high, with small forts for around 30 men every mile, and observation turrets every third of a mile. It was fronted by a wide, deep, V-shaped ditch, and between wall and ditch was an entanglement of forked and sharpened branches – the Roman equivalent of barbed wire. Gateways at the milecastles provided the only approved crossing-places, such that traffic over the border could be controlled and tolls perhaps levied on traders. Outpost forts were built north of the wall to facilitate long-range patrolling. The system of mile-castles and turrets – though without the wall between – was extended far down the Cumberland coast. As work progressed, plans were modified: the thickness of the wall was reduced; sections built originally of turf were replaced in stone; a continuous linear earthwork (the Vallum) was dug to the south, defining a broad belt of land behind the wall as a ‘military zone’; and, most importantly, a series of regimental forts were built along the line of the wall, at first 12, eventually 16, putting 6 or 7,000 auxiliary troops on the frontier line itself.

Debate about the purpose of the wall continues. The recent discovery of the thicket of spikes along its front implies a military purpose. But contemporary Roman military doctrine had it that pre-emptive and punitive aggression was the best form of defence, so the wall was more likely intended as a police and customs barrier. Even this, perhaps, is to over-rationalize a profoundly political project. If Trajan offered battles and military glory, Hadrian offered instead great buildings, monuments to imperial grandeur, a symbolic marking out of boundaries, a way of ‘separating the Romans from the barbarians’. Hadrian’s frontier works, moreover, were part of a larger package. It had been necessary to settle the soldiers – with bribes, flattery and hard work. But then, having ritually charged the boundaries of the empire by marking them with lines of earth and stone, Hadrian turned his attention to the people within, the subjects of Rome, all of whom were now to become stakeholders and loyalists in an imperial commonwealth. The showcases of the new world order would be, of course, the cities of the empire.

Here, not only was Hadrian’s the vision, but very often so too were the plans, the blueprints, the engineering needed to monumentalize it in stone. Hadrian, it seems, was something of an architect. His masterpiece was the Pantheon in Rome. In it, the structurally redundant pillars of Greek temple architecture were abandoned, and the central shrine, released from its cage, became the whole building. But instead of a traditional box, the full potential of the Roman vault was realized, and the shrine was built as a huge dome, one describing a complete and perfect circle from apex to floor and from side to side. The huge span, an awesome 43.20 m, has been surpassed only in modern times, an achievement made possible by having an immense ring of concrete as foundation, by the use of top-quality Roman mortar, and by a careful grading of the thickness and types of material used in constructing the dome from top to bottom.

Rome, as ever, was intended as a model for the provinces. Hadrian, as he travelled, initiated great building projects in city after city. Today, when we visit ruined Roman cities around the Mediterranean, a good proportion of what we see belongs to the ‘golden age’ of Hadrian and Antoninus Pius, his immediate successor. Over several decades, the downtown areas of scores of imperial cities were transformed into building sites and recast with new complexes of monumental classical architecture and baroque decoration. Take Athens, for example, an old Greek university town that was a special favourite of the philhellene emperor. Close to the ancient agora, he built a library complex, more than 120 m by 80 m in extent, complete with walled garden, lily-pond, surrounding colonnades, and sitting-out places. On the edge of the city, he completed – 600 years after the foundations were laid – the Temple of Olympian Zeus, one of the largest classical temples in the world, of which 17 towering Corinthian columns still stand. More than that, in the area around the temple, he laid out an entire new city suburb, memorializing this achievement in a stone arch positioned between the old and new cities: ‘This is Athens, the ancient city of Theseus’ reads the inner face, ‘This is the city of Hadrian, not of Theseus’ reads the outer. The past – the glory that was Greece, the fount of classical civilization, the foundation on which Hadrian planned to build – this was honoured. But it was added to, made yet grander, renewed by Hadrianic monuments which appropriated that past to the exigencies of the present. Here, however, in his great projects of acculturation, no less than Trajan in his of subjugation, Hadrian discovered that empire had limits.

Not for the first time in the history of the Empire, the Jews of Palestine proved themselves the hardest rock of resistance. For 200 years, the peasants of Galilee and Judaea had rejected the temptations of Romanitas, and withstood the insults and bullying of its local agents. At root, they knew, Rome meant the rule of landlords, tax-collectors and government soldiers. The trinkets and trappings were mainly for the rich. The new gods were pagan idols offensive to the righteous. Here, for Hadrian, on the other hand, was a worm of corruption within his commonwealth, a class of men whose boorishness could feed an irrational opposition and a weakening of the body-politic. In AD 70, the Jewish Temple in Jerusalem had been destroyed, the Temple tithe diverted to Jupiter, and a Roman legion stationed on the Temple Mount. Yet, Judaism and a Jewish national identity had survived, even in Roman-occupied Jerusalem, where at least seven synagogues remained. The race, the monotheism and the nationalism of the Jews made them an enemy within, and Hadrian came to Jerusalem in AD 130 determined to destroy them, to ethnically cleanse his empire, to obliterate an ideological alternative, to impose by force the Graeco-Roman norms that had become compulsory.

Jerusalem was re-founded as a Roman colony – Aelia Capitolina – and a temple for the worship of Hadrian-Jupiter was built on the Temple Mount. The practice of circumcision – the single most distinctive marker of Semitic identity – was banned on pain of death. Hadrian declared himself successor to Antiochus Epiphanes, the Greek ruler who had tried to destroy Judaism three centuries before, and he erected a monument to Pompey, the first Roman enemy of the Jews. Alexandria and Cyrene, Greek cities devastated in the Jewish Revolt of AD 115–118, were conspicuously reconstructed. By AD 132 the Jews had been goaded into revolt. In scale, duration and ferocity, the resistance fully matched that of AD 66–73. Led by Bar-Kokhba, ‘Son of the Star’, a new Jewish messiah who was to prove himself a brilliant guerrilla commander, and by the radical-nationalist rabbi Akiba, the revolutionaries took immediate control of Jerusalem, restored the worship of Yahweh, and issued coins announcing the ‘Redemption of Israel’. Quickly reinforced by returning emigrés and a general rising in the countryside, the rebels overwhelmed local Roman forces. Two legions were not enough. The empire was trawled for troops. With fresh legions poured into the war zone, Jerusalem was retaken; but the rebels re-established themselves at Herodium and various remote desert cave-complexes. It took four years to crush the revolt entirely. By the time it ended, in AD 136, 50 fort-resses and 1,000 villages had been destroyed, and 500,000 people killed or enslaved; Palestine, Dio Cassius tells us, was left a wilderness of wolves and hyenas feeding on corpses.

By now, Hadrian, back in Italy, was embittered and dying. His vision of a commonwealth of peoples had been consumed in the Palestinian apocalypse: all that remained there was the arrogance of foreign overlords and pagan gods. His relations with his commanders and officials had soured. The emperor’s philhellenism, his open homosexuality, his public affair with the beautiful Greek youth Antinoös, the creation of a cult in his honour after he was drowned in the Nile: all this offended the sensibilities of conservative members of the Roman governing class. It seemed to many to symbolize the decadence of the regime. The withdrawal from Mesopotamia, the failure to advance elsewhere, the freezing of the frontier lines, the favouritism towards Greeks, the diluting of Roman citizenship, the spilling out of imperial wealth on the embellishment of provincial cities: all highly questionable. It was not just Jewish freedom-fighters who contested the Hadrianic vision; so, too, did the Old Guard at home.

Hadrian retreated to the grand country residence he had built for himself at Tivoli, in the hills a short distance from Rome, a palace and garden-city modelled on Athens and Alexandria, sprawling across some 300 hectares (making it not much smaller than Rome itself). He seemed no longer to care. He named as successor a handsome young fop with a reputation for idleness, self-indulgence, and reading love poetry and cookery books while reclining on scented cushions strewn with flowers. Presumably he was the old man’s fancy. The fop predeceased his master. Hadrian then adopted an old friend: Titus Antoninus – soon to be Antoninus Pius – and thereafter relapsed into bitter apathy and derangement, awaiting death – sometimes, it is said, trying unsuccessfully to hasten it – a man psychologically and politically broken by the contradictions of an empire at bay.

Antoninus Pius (AD 138–161) was mercifully free of ambition, whether of Trajanic or Hadrianic type. The spirit of the age was mediocrity, and Antoninus was a fitting figurehead. Neither great generals, nor revolutionary leaders, nor reforming ministers were needed; merely an administrator who would do nothing to upset the geopolitical equilibrium. Expansion had ended, but retreat had not yet begun. This was the essence of Gibbon’s golden age: ‘In the second century of the Christian era, the empire of Rome comprehended the fairest part of the earth, and most civilised portion of mankind. The frontiers of that extensive monarchy were guarded by ancient renown and disciplined valour. The gentle, but powerful, influence of laws and manners, had gradually cemented the union of the provinces. Their peaceful inhabitants enjoyed and abused the advantages of wealth and luxury. The image of a free constitution was preserved with decent reverence: the Roman Senate appeared to possess the sovereign authority, and devolved on the emperors all the executive powers of government. During a happy period of more than fourscore years, the public administration was conducted by the virtue and abilities of Nerva, Trajan, Hadrian, and the two Antonines.’(16) Peace, order, wealth, civilization: the 2^nd century empire certainly offered these. But all the while the mole of history was at work. Several phases passed in quick succession: the exhaustion of expansion under Trajan; the consolidation of frontiers under Hadrian; an equilibrium of forces under Antoninus; and then, under Marcus, a collapse along the upper Danube and a great flood of German tribesmen into northern Italy.

On the surface, all seemed calm. Almost everywhere there was peace. The only major campaign of Antoninus’s reign was in northern Britain, a push forwards to take in the Southern Uplands and form a new line between the Forth and the Clyde. The reasons are obscure, but they were surely to do with improving frontier security; not that it worked, whatever the plan may have been, for the Romans were back on Hadrian’s Wall a generation later. Elsewhere, it was a matter of small local campaigns and police operations – the straightening out of a stretch of frontier in Germany, a war against mountain ‘brigands’ in Mauretania, a tax revolt in Egypt: routine stuff. Meantime, across the empire, materialized in the archaeology of ten thousand Roman sites, the imperial economy was booming. Basilicas, temples, bath-houses, theatres, amphitheatres and shopping malls went up in town centres. Grand town-houses filled the suburbs, while villas were built on nearby country estates. Local aristocrats thus equipped themselves to shuttle comfortably between the amenities, social round and public duties of the town, and the relative tranquillity of their rural seats. A Mediterranean ambience was universal. A single Graeco-Roman cultural koine defined the elites of the empire. Everywhere it was colonnaded courtyards, frescoed and mosaic-floored living rooms, gardens filled with classical statuary, box-hedges and marble fountains. People drank wine, conversed in Greek or Latin, made offerings to Jupiter, and read – or claimed to read – the classics. Trade and the crafts flourished, and so did the larger farms with a surplus to sell and good roads or waterways to take it to market: for the empire and its civilization, the soldiers and the elite, the forts and the towns, all needed an unceasing supply of grain, meat, salt, cloth, leather, timber, stone, pottery, ironwork, bronze, silver, gold, and much else.

Yet the true stakeholders were a minority. The majority were slaves, serfs, poor peasants, or at best middling peasants with enough for themselves and their families but little to spare. These were perhaps three-quarters or more of the empire’s people. They were the producers from whom surplus was creamed in tax, rent, interest and forced labour – the surplus that was invested in forts, towns and villas, the surplus that made empire and civilization possible. As things stood, though the empire brought no benefit, though it offered only a life of toil and trouble to the mass of rural people, nonetheless it generally left them enough to carry on, enough for some sort of life. But the balance was a fine one. The margin of safety for millions – the margin between how much went in tax and what was needed to feed a family and stock a farm – was perilously narrow. Tip the balance just a little, and millions might plunge to ruin.

For the state, too, the balance was fine, the margin of safety narrow: it currently took just enough in tax to support the minimum of soldiers needed to man the empire’s defences. But the line – thousands of miles of stone, earth, iron and flesh – was stretched thin. Dangerously thin, as the skies darkened in the far north.