The Military of Rome III

■ Military Standards and Banners

Another of Marius’ innovations was the introduction of a single silver eagle (aquila), mounted on a staff, as a legionary standard. It is difficult to know just what significance should be attached to this change, because we have no clear information about the military standards which were previously in use. The eagle was a bird sacred to Jupiter. According to one source, there had previously been five legionary standards. Apart from the eagle, these exhibited the forms of wolves, bears, minotaurs and horses, and they were carried severally before the several ranks of the army in battle. But from Marius’ time, they were relegated to subordinate and ceremonial usages.

The legionary eagles were later made of gold and they were embellished with wreaths and other ornaments. In peacetime, they were kept in the state treasury (aerarium) at Rome, the old temple of Saturn. In wartime, they were carried with the legion and had a little sanctuary allotted to them in the camp. They were objects of quasi-religious veneration.

This quasi-religious function of the standards was in conflict with their practical purpose. In so far as the standard was a sacred object symbolizing the corporate existence of a military unit, it qualified for the care and protection of the soldiers whom it represented and could not properly be exposed to danger of capture by the enemy in battle. Its loss was, in fact, regarded as a great disgrace. The standard therefore had to be placed behind the front line and surrounded by troops who would defend it.

Schoolboys are – or used to be – familiar with Caesar’s anecdote of the standard-bearer who leapt down from his ship as it beached on the Kentish coast, with an exhortation to the hesitant legionaries to follow him if they did not intend the betrayal of their eagle into enemy hands. An earlier example of the same attitude occurs in Plutarch’s account of the battle of Pydna. On this occasion, a captain of one of the Italian contingents seized his unit’s ensign and flung it into the enemy phalanx. Thus blackmailed by the threat of dishonour, his men redoubled their efforts to break the phalanx. For, as Plutarch observes, the Italians in particular regarded it as ignominious to desert their standards.

If, however, the standard was a sacred object which required protection, it could not discharge its practical function – which was to serve as a rallying point. As such, its place was in the forefront of the battle. The legionaries could not be expected to look over their shoulders to discover where they should take their stand. The very name of the standards in Latin, signa, suggests that they were in fact signals, and as tactics became increasingly mobile and less uniform, the need for them increased. Incidentally, the Greeks of the fifth century BC had made no corresponding use of military standards in their compact phalanx battles.

A study of ancient references to the position of the standards on the battlefield suggests that they may have been located immediately behind the front line. They were thus protected, and yet at the same time sufficiently far advanced to serve as marking signals for the greater part of the army. On the other hand, the whole point of Marius’ innovation may have been to confer a single standard on the legion, which would serve its emotional needs, at the same time leaving the standards of the smaller units free to be used, without sentimental inhibitions, for practical purposes. By contrast with legionary standards, the old signalling staves of the maniples had embodied no sacred animals. They had exhibited the open palm of a hand on a raised spear, but were later decorated with garlands and other emblems. When maniples were absorbed into cohorts, the cohort took the leading maniple’s standard.

Similarly, the cavalry standards (vexilla), consisting of flags suspended from a kind of yard-arm and identifying units, would lose their more emotional significance with the adoption of the uniform legionary emblem. By Marius’ time, the Italian cavalry had largely been superseded by overseas cavalry forces (auxilia), who perhaps did not share the Italian veneration for standards and banners. The eagle remained a permanent symbol throughout later centuries of military development. But other forms of standard were also imitated from the usage of outlying peoples on Rome’s frontiers. An interesting example is the draco, which was a windsock of coloured silk, with the silver head and gaping jaws of a dragon.

The Italian captain distinguished by his gesture at Pydna had been a Pelignian. Marius came from Arpinum, a town which had enjoyed full Roman citizen rights since the beginning of the second century BC. Arpinum was not far from the territory of the Peligni, and Marius was perhaps acutely conscious of the importance of military standards and banners in terms of local sentiment. As an eminently practical commander, he must also have been aware of the difficulties which such sentiments created. It is possible to regard the silver eagle as his solution.

■ The Frontiers of Empire

The Roman navy, at such times as it could be said to exist at all, was always the junior service. However, Augustus was at pains to maintain it, for he needed to preserve lines of communication between Italy and the provinces. Of no small account were the naval forces whose allegiances had been transferred to him after the defeat of Antony and Cleopatra, and he was able to establish fleets in the eastern and western Mediterranean and in the Black Sea. Other naval squadrons operated on the Danube, the Rhine and in the English Channel.

Campaigns in Illyricum, under Augustus’ destined successor, Tiberius, had safeguarded the route to the east by the Via Egnatia and Thessalonica, and the freedom of the Adriatic from pirates was further assured by the construction of the naval base at Ravenna. The Mediterranean in general was well policed under Augustus, and his was the last Roman administration to take effective measures against piracy.

Preoccupation with sea routes was the logical accompaniment of provincial road-building which proceeded under the Empire. Italy in the time of the Republic had acquired a good road system. Apart from that, the Via Egnatia, referred to above, and the Via Domitia, which led from the Rhône to the Pyrenees, were also Republican achievements. In Augustus’ time, new Alpine roads were made and communications facilitated with the Danube. The characteristically straight Roman roads, adhering where possible to high ground, were planned to satisfy military requirements. But at the same time, of course, they opened the way to trade and assisted official contacts.

The legions which in the first century AD extended and, later, defended the frontiers of the Empire were distinguished by names and numbers, though some of the numbers were duplicated. The names commemorated the patrons or creators of the legions, as for example the Legio Angusta, or else they referred to some event in regimental history, or marked a local connection, as in Macedonica or Gallica. Augustus’ army originally contained 28 legions. But three of these were annihilated in the great Roman military disaster of AD 9, when Augustus’ general, Publius Quinctilius Varus, was treacherously ambushed by the German chief Arminius in the Teutoburgian Forest. The numbers of these three ill-starred legions were as a consequence never allotted to Roman legions at a later date.

A Roman governor, in charge of an imperial province, ordinarily ranked as a legatos of the emperor. Legions apart auxiliary troops including cavalry contingents were an important element in the garrison of a province. Under Augustus, auxiliaries, which during the first century BC had been composed of foreign troops, once more began to recruit Roman citizens. This was in part because Roman citizenship itself had by now been conferred on many communities and individuals outside Italy. The social distinction being lost, auxiliaries tended to be integrated with legions. In permanent frontier stations auxiliary cavalry and infantry were posted at first from distant provinces. But as a matter of convenience, auxiliaries came to be recruited locally and the distinction between the legionaries and auxilia was accordingly once more obscured. However, military policy favoured independent cavalry tactics. From the reign of Trajan onwards, tribal non-Romanized units, known as numeri, were recruited; their role corresponded in some ways to that of auxilia in more ancient times.

The disaster which the Romans suffered in Germany under Varus was the result of an attempt to establish frontiers farther east, on the Elbe. Its effect was that Roman emperors were from that time onward content, as Julius Caesar had been, to rely on punitive and retaliatory action in order to assert a Roman presence on the Rhine. Augustus himself, at the end of his life, made it quite clear that his territorial ambitions were not unlimited. Defence, however, often entails offensive initiative, and he had been at great pains to secure the line of the Danube.

The most suitable location of frontiers was a question which left room for uncertainty, above all in the reign of an emperor of unbalanced mind, such as Gaius (Caligula) proved to be. His inexplicable vacillations could well have been damaging to Roman prestige, and the expansionist policies of the mild-mannered Claudius, who succeeded him, may have been necessary to ensure that enemies beyond the frontier were left with no illusions about the reality of Roman strength. Claudius, in need of a military reputation, added first Mauretania, then Britain to the Empire. Roman domination was carried farther by Trajan, who annexed Armenia and temporarily occupied much of Parthia. Rome, however, was never able to impose itself finally on the Parthians.

■ The Stabilization of Frontiers

The murder of Domitian in the year AD 96 was the outcome of domestic discord. Nevertheless, it gave great public satisfaction. Apart from his other shortcomings, the tyrant had failed to make adequate arrangements for a successor. The Senate appointed a new princeps, Marcus Cocceius Nerva, and Tacitus was pleased to see in this constitutional gesture a revival of Republican sentiment. Nerva was an old man at the time of his elevation. He was also childless, and after one year of power he appointed a loyal and able officer, Marcus Ulpius Traianus (Trajan), as his colleague and successor. The appointment was timely, for Nerva died early in the following year. Under Trajan, imperial expansion was renewed, and as one of Rome’s greatest soldier emperors, he was shrewd enough to nominate an equally great successor. The formal nomination and adoption which usually secured the imperial succession was much more satisfactory than the common hereditary process. It generally ensured that the successor would be a military commander, for with exceptions, one of which we have just recorded, none but a soldier could hope to survive. The Empire depended for defence and government upon military force. As for the principle of adoption itself, Roman reverence for legal forms lent it all the sanctity of a blood-tie. One may compare the relationship of patron and protégé (cliens), which we have already had occasion to notice.

Hadrian (Publius Aelius Hadrianus) who, as a connection by marriage, was Trajan’s ward and became emperor on his death, in many ways reversed the policies of his predecessor. But this does not prove that either he or Trajan was wrong. Times were changing. The steady westward migration of peoples in Asia and Europe meant that pressure on Rome’s frontiers was steadily mounting. Under Trajan, those frontiers had attained unprecedentedly wide dimensions. Hadrian saw the need for contraction and consolidation, and this policy was marked in vulnerable areas by the construction of fixed fortifications, signal posts and entrenchments. A line of forts linked by palisades, protected the intrusive salient of territory between the upper reaches of the Rhine and the Danube. Hadrian’s name is notably associated with the Roman frontier works across north Britain from the Tyne to the Solway. The line of forts and base camps, connected by a mural barrier, replaced an earlier linked chain of forts slightly to the south. “Hadrian’s Wall” was initiated as the result of the Emperor’s visit to Britain in AD 122; Hadrian spent a great deal of his reign in visiting outlying provinces. The Wall exemplifies the principles of Roman frontier defence as they existed in many sectors of the Empire. A chain of strong-points was connected by a well-defined communicating road (limes) along which troops could move with efficiency and speed.

Antoninus Pius (138–161), who succeeded Hadrian, presided over an epoch of comparative peace and plenty in the Mediterranean core of the Empire. But the price of social well-being was continual vigilance and preparedness on the frontiers. In Britain, Antoninus tried to advance the frontier – as he did in Germany – and built another wall in the form of a turf embankment on a cobblestone base, farther north, from the Forth to the Clyde. But the time came when this could no longer be defended, and after only 23 years it was decided to withdraw southwards once more and rely solely on Hadrian’s stone structure for the defence of Roman Britain.

The recourse to engineering skills in order to solve manpower problems had been Julius Caesar’s answer. Rome’s wars against the barbarians were a continual struggle against numerical odds, and with the help of technology the Romans strove to make good what they lacked in numbers. Twenty-eight legions had been all too few for Augustus’ original ambitions, and when he lost three of them in Varus’ disaster, he saw the need to reduce military commitments and shorten the perimeter of the imperial frontiers.

The military garrisons which manned frontier areas were (as a matter of policy on which we have already commented) not all nationally homogeneous. But they tended to form settled communities as a result of relationships with local women, and the resulting settled habits and lack of mobility in themselves constituted a disadvantage. However, legions were withdrawn from Britain at various dates during the centuries of Roman rule, to meet pressures in other parts of the Empire, and such withdrawals, even though the legions by this time were not all first-line troops, opened the way inevitably to northern or seaborne invaders to make incursions.

■ The Task of Marcus Aurelius

Marcus Aurelius Antoninus, who succeeded to the principate at the death of Antoninus Pius in AD 161, was also of a quiet and philosophic disposition, but unlike his predecessor he was faced with the necessity for continual warfare. The fact that he was able to meet the challenge of military duty with energy and unbroken resolve indicates some kind of spiritual triumph over his natural temperament, at the same time making him a practising as distinct from a purely academic philosopher.

War against Parthia (162–3) was only a prelude to barbarian incursions on the Danube front (166). It was already well recognized that responsibility for imperial defence was more than a single emperor could support. An emperor’s nominated successor, who now ordinarily received the title of “Caesar”, was also a colleague. Marcus Aurelius was not very fortunate in his colleague Lucius Verus, whose adoption derived from a decision of Hadrian. Marcus, showing perhaps poor judgment of character, arranged that the task of imperial government should be shared, and Verus, ruling as an equal on a collegiate basis, took command of the war against Parthia, which was won for him by his able officer Avidius Cassius.

The major cities of Parthia were captured, but this victory, like that of Trajan, though westward territories were annexed, could not lead to permanent Roman occupation of Parthia. The days were past when Romans and Parthians fought each other with characteristic national weapons and battles were a conflict of highly disciplined legionaries with incalculable swarms of mounted bowmen. Arrian, writing on military tactics in the time of Hadrian, testifies to the diversification of arms and armour and the variety of combatant methods employed by the Roman army at that epoch. Trajan’s Column and other monuments tell the same story. The Romans had among their own contingents heavily mailed horsemen on the Parthian model; nor did they lack archers who could retaliate against the Parthians. If they were never able to bring the Parthian Empire within the bounds of their own, this was probably because they lacked sufficient troops to hold what had been conquered. Such vast deserts were in any case ungovernable.

Lack of numbers also told heavily against Roman defence on the Danube, and it should be stressed that Rome was now seriously on the defensive in this area. Various barbarian tribes, forced westwards and southwards by migratory pressures, crossed the Alps and reached Aquileia at the northern extremity of the Adriatic Sea. Italy was threatened as it never had been since the days of the Cimbric invasion, but the barbarians did not capture Aquileia, lacking the equipment for assaults on fortified towns. Marcus Aurelius, despite the inferior ability of his colleague, was well served by his generals on the Danube front. Lucius Verus in any case died on active service in 169, and Marcus was left in sole command.

There seems to have been a good deal of collaboration between the German tribes of the upper Danube and the Sarmatians farther east. Roman armies, relying simply on mobility and speed, had to turn abruptly from one threat to another. The invaders were defeated in a series of arduous campaigns, forced back across the Danube and reduced to quiescence. But such warfare spelt an end to current methods of frontier defence and, in years which followed, Roman strategists had to think increasingly in terms of fortified zones rather than defensible lines.

Unfortunately, the manpower problem in the time of Marcus Aurelius became all the more critical on account of a devastating plague which the army brought back from its eastern wars. Sheer lack of manpower obliged Marcus to establish a German militia, settled within the imperial frontiers, as a way of combating German threats from without. Military service was the price of the land which the settlers occupied. As the frontiers became less distinct, so also did the definition of Roman nationality. The operations of Marcus Aurelius and his officers secured the line of the Danube, but in the large frontier province of Dacia to the north of the river, which Trajan had previously annexed, a right of way was granted to the barbarian tribes, allowing them to preserve communications with their eastward compatriots. In some sense, the Empire was now provided with insulating zones but – to press the metaphor – this insulation could become a semiconductor of extraneous forces.

Marcus Aurelius would probably have rendered the territory beyond the Danube more secure, but in AD 175 he had to meet the revolt of his eastern deputy Avidius Cassius. It would seem that Cassius had been deceived by a false report that Marcus was dead, and his dissident action hardly had time to gather impetus before he was murdered by one of his own centurions. Avidius Cassius would in any case have been a preferable alternative to the Emperor’s ineffective son Commodus, who eventually filled the role of official colleague and successor.

■ Septimius Severus and his Army

The principate of Commodus lasted 12 years, which should have been long enough to secure the succession, but Commodus did not allow the matter to trouble him. He was eventually murderer as the result of a conspiracy hatched by his Praetorian Guard commander, who had for some time shared the real power with other favourites, and at last decided that the present emperor was no longer necessary. During the next year, two emperors were proclaimed and then murdered, while the Praetorians tried to make up their minds. At last, they gave support to Septimius Severus, who commanded the Danube legions. The legions themselves, in fact, provided a firmer backing than Praetorian caprice.

Septimius had to fight for the imperial throne against other contenders, who were also supported by provincial armies. He was victorious in the ensuing struggle, partly because he commanded more troops than his adversaries and partly because he was nearer to Rome – still the key point. He temporarily came to terms with his northern rival Clodius Albinus, governor of Britain, recognizing him as a colleague. It is surprising that Albinus was deceived so easily. Septimius had time to march eastward and defeat his other opponent, Pescennius Niger, in a series of battles in Asia Minor and Syria. He was then in a position to renew hostilities against Albinus, who had advanced into Gaul and rallied the western provinces of the Empire in his favour. Perhaps Albinus also had been playing for time. The numbers engaged in the decisive battle near Lugdumum (Lyon) are reported as being equal, and the issue for long hung in the balance, but Septimius was completely victorious, deciding the battle by his use of cavalry as an independent arm.

Septimius Severus’ military ability was allied to shrewd political insight. On being proclaimed emperor, he had been quick to occupy Rome and disband the Praetorian Guard. He then re-established the Praetorians to suit his own convenience. In the past, the Praetorian cohorts had normally been recruited from Italy, but Septimius threw membership open to all legionaries. This meant in practice that Praetorians were picked from the Illyrian legions which had supported him. They continued to serve him admirably as an imperial corps d’élite in the course of his eastern campaign.

Having eliminated other imperial pretenders, Septimius undertook an effective punitive expedition against the Parthians, who had given support to Niger, his eastern rival. He also had to act promptly in Britain, for the province, stripped of troops by Albinus for his continental adventure, was badly exposed to Caledonian invaders from the north. But Septimius’ British campaign was incomplete and he was preparing to renew hostilities when he died at Eburacum (York) in AD 211.

Septimius Severus admired soldiers and believed in them, particularly in the soldiers of the Roman army. For him, their welfare was a paramount consideration, and one cannot help feeling that his attitude, despite its serious economic implications, was right. Roman civilization had come to depend completely on military power capable of defending the frontiers, and citizens who enjoyed the peace and comfort of metropolitan territories could at least be expected to support the defence effort with their tax contributions. Septimius, in fact, made sure that they did so.

Among other reforms which favoured the soldiers, he legislated that they should be able to marry legally while on service. This facility had not previously existed, though emperors in the past had given some sort of recognition to the relations which soldiers contracted with local women and to the children which resulted. Official attitudes on this subject seem to have been in conflict. On the one hand, the serving soldier was discouraged from forming local ties which might divert him from his principal allegiance to Rome. On the other, it was desired that he should feel at home in the army. The new legislation rectified anomalies. In any case Septimius’ son, colleague and successor, Marcus Aurelius Antoninus (known by the nickname of Caracalla) in subsequent years recognized the Roman citizenship of all freeborn provincials. The new constitutional enactment was not credited by an unimpressed posterity with generous motives, but regarded rather as a means of widening liability to tax. But it meant that civilians in general made a greater contribution to the defence budget. Of such a policy, Septimius would have approved.

Military and Civil Reorganization

The decade following Aurelian’s death was marked by another sequence of short-lived emperors. The year AD 284, however, saw the proclamation of the Emperor Diocletian (Gaius Aurelius Valerius Diocletianus) by troops in Asia Minor. Diocletian won the war against his rival and appointed Maximian (Marcus Aurelius Valerius Maximianus) as his colleague.

In 286, Diocletian permitted to Maximian the title “Augustus”, which indicated possession of the supreme power. From that time on, they ruled jointly, and in 293 each “Augustus” appointed himself a colleague who bore the title of “Caesar”. Four Imperial Headquarters, with their staffs, thus resulted. By regularizing procedures which had proved expedient in the past, Diocletian was in fact giving recognition to the inevitability of the collegiate principle. The Empire was too big for a single command. Troops might be transferred from Britain to the Danube in two months: perhaps less, if full use were made of Rhine river transport. But the Euphrates frontier was another matter. East and West were two Empires within a single civilization, and Diocletian wished to ensure that they should remain collegiate, not rival Empires. To some extent, their mutual independence was an accomplished fact which he was forced to recognise.

In re-establishing a co-optive procedure as the basis of imperial succession, Diocletian invoked another traditional expedient. Heredity notably in the family of Septimius Severus – based simply on blood-ties – had been productive of some grotesque results. Similarly, “praetorianism”, whether practised by the Guard itself or by the provincial legions, was simply an invitation to mutiny and murder. Because an emperor needed to be a soldier, it was too easily assumed that he needed to be nothing else. As in the first century AD, a blend of two principles was now expected to give best results. Co-option was confirmed by family affinities. The daughter of Diocletian and the step-daughter of Maximian married Galerius and Constantius, the two co-opted “Caesars”.

It was also arranged that the two “Augusti” should retire from office after 20 years and give place to their “Caesars”, who, assuming the supreme title, should appoint new “Caesars” as junior colleagues. Diocletian himself retired to his palace at Salonae (near modern Split in Jugoslavia). His choice of residence is itself significant. The imperial centre of gravity now lay in the Balkan peninsula and southeast Europe. Diocletian, like several of his imperial predecessors, had been of Balkan extraction. Rome was rapidly becoming no more than the ceremonial capital of empire. In practice, it was already merely a provincial capital, and the Senate was treated by Diocletian as if it were a body of town councillors. He never entered Rome during the first 20 years of his reign.

With his stern eye for realities and disregard for empty forms, Diocletian also realities and disregard for empty forms, Diocletian also relegated the old names of Republican magistracies to purely civil functions, and increasingly used distinct titles for military appointments. Like Septimius Severus, he realized that Rome’s greatest problem was one of recruiting, and he seems to have almost doubled the number of soldiers by increasing their pay. In order to do this, it was necessary to combat the monetary inflation which had long been associated with debasement of the Roman coinage. Diocletian went to the heart of the problem by exacting taxes in kind and maintaining his army with the proceeds.

Above all, Diocletian was an administrator and organizer, but it must not therefore be inferred that he was an “armchair” strategist. His reforms were worked out in the course of action and, like most Roman emperors who survived the first months of power, he had been obliged to fight for his position, suppress revolts and restrain barbarians. Maximian, his fellow “Augustus”, was an ambitious man, but he knew better than to challenge Diocletian on the field of battle.

Maximian, as Emperor of the West, had in fact his own military problems. Of these, the most intractable was presented by Carausius, a rebellious admiral of the British Channel fleet. Irrepressible, Carausius was for some time endured by the two “Augusti” as a kind of supernumerary colleague in Britain and north Gaul. Eventually, Maximian’s “Caesar”, Constantius, drove him from Boulogne and, continuing the war against Carausius’ murderer and successor, restored Britain to its former allegiance.