Table of Contents
References & Edit History Quick Facts & Related Topics
Quick Facts

The consolidation of the empire under the Julio-Claudians

The establishment of the principate under Augustus

Actium left Octavian the master of the Roman world. This supremacy, successfully maintained until his death more than 40 years later, made him the first of the Roman emperors. Suicide removed Antony and Cleopatra and their potential menace in 30 bc, and the annexation of Egypt with its Ptolemaic treasure brought financial independence. With these reassurances Octavian could begin the task of reconstruction.

Roman emperors*
*For a list of the Eastern emperors after the fall of Rome, see Byzantine Empire.
Augustus (Augustus Caesar) 27 BC–AD 14
Tiberius (Tiberius Caesar Augustus) 14–37
Caligula (Gaius Caesar Germanicus) 37–41
Claudius (Tiberius Claudius Caesar Augustus Germanicus) 41–54
Nero (Nero Claudius Caesar Augustus Germanicus) 54–68
Galba (Servius Galba Caesar Augustus) 68–69
Otho (Marcus Otho Caesar Augustus) 69
Vitellius (Aulus Vitellius) 69
Vespasian (Caesar Vespasianus Augustus) 69–79
Titus (Titus Vespasianus Augustus) 79–81
Domitian (Caesar Domitianus Augustus) 81–96
Nerva (Nerva Caesar Augustus) 96–98
Trajan (Caesar Divi Nervae Filius Nerva Traianus Optimus Augustus) 98–117
Hadrian (Caesar Traianus Hadrianus Augustus) 117–138
Antoninus Pius (Caesar Titus Aelius Hadrianus Antoninus Augustus Pius) 138–161
Marcus Aurelius (Caesar Marcus Aurelius Antoninus Augustus) 161–180
Lucius Verus (Lucius Aurelius Verus) 161–169
Commodus (Caesar Marcus Aurelius Commodus Antoninus Augustus) 177–192
Pertinax (Publius Helvius Pertinax) 193
Didius Severus Julianus (Marcus Didius Severus Julianus) 193
Septimius Severus (Lucius Septimius Severus Pertinax) 193–211
Caracalla (Marcus Aurelius Severus Antoninus Augustus) 198–217
Septimius Geta (Publius Septimius Geta) 209–212
Macrinus (Caesar Marcus Opellius Severus Macrinus Augustus) 217–218
Elagabalus (Caesar Marcus Aurelius Antoninus Augustus) 218–222
Alexander Severus (Marcus Aurelius Severus Alexander) 222–235
Maximinus (Gaius Julius Verus Maximinus) 235–238
Gordian I (Marcus Antonius Gordianus Sempronianus Romanus) 238
Gordian II (Marcus Antonius Gordianus Sempronianus Romanus Africanus) 238
Pupienus Maximus (Marcus Clodius Pupienus Maximus) 238
Balbinus (Decius Caelius Calvinus Balbinus) 238
Gordian III (Marcus Antonius Gordianus) 238–244
Philip (Marcus Julius Philippus) 244–249
Decius (Gaius Messius Quintus Trianus Decius) 249–251
Hostilian (Gaius Valens Hostilianus Messius Quintus) 251
Gallus (Gaius Vibius Trebonianus Gallus) 251–253
Aemilian (Marcus Aemilius Aemilianus) 253
Valerian (Publius Licinius Valerianus) 253–260
Gallienus (Publius Licinius Egnatius Gallienus) 253–268
Claudius (II) Gothicus (Marcus Aurelius Claudius Gothicus) 268–270
Quintillus (Marcus Aurelius Claudius Quintillus) 269–270
Aurelian (Lucius Domitius Aurelianus) 270–275
Tacitus (Marcus Claudius Tacitus) 275–276
Florian (Marcus Annius Florianus) 276
Probus (Marcus Aurelius Probus) 276–282
Carus (Marcus Aurelius Carus) 282–283
Carinus (Marcus Aurelius Carinus) 283–285
Numerian (Marcus Aurelius Numerius Numerianus) 283–284
Diocletian (Gaius Aurelius Valerius Diocletianus) East only 284–305
Maximian (Marcus Aurelius Valerius Maximianus) West only 286–305
306–308
Galerius (Gaius Galerius Valerius Maximianus) East only 305–311
Constantius I Chlorus (Marcus Flavius Valerius Constantius) West only 305–306
Severus (Flavius Valerius Severus) West only 306–307
Maxentius (Marcus Aurelius Valerius Maxentius) West only 306–312
Licinius (Valerius Licinianus Licinius) East only 308–324
Constantine I (Flavius Valerius Constantinus) 312–337
Constantine II (Flavius Claudius Constantinus) 337–340
Constans I (Flavius Julius Constans) 337–350
Constantius II (Flavius Julius Constantius) 337–361
Magnentius (Flavius Magnus Magnentius) 350–353
Julian (Flavius Claudius Julianus) 361–363
Jovian (Flavius Jovianus) 363–364
Valentinian I (Flavius Valentinianus) West only 364–375
Valens (Flavius Valens) East only 364–378
Procopius East only 365–366
Gratian (Flavius Gratianus Augustus) West only 375–383
Valentinian II (Flavius Valentinianus) West only 375–392
Theodosius I (Flavius Theodosius) 379–395
Arcadius (Flavius Arcadius) East only 395–408
Honorius (Flavius Honorius) West only 395–423
Theodosius II East only 408–450
Constantius III West only 421
Valentinian III (Flavius Placidius Valentinianus) West only 425–455
Marcian (Marcianus) East only 450–457
Petronius Maximus (Flavius Ancius Petronius Maximus) West only 455
Avitus (Flavius Maccilius Eparchius Avitus) West only 455–456
Leo I (Leo Thrax Magnus) East only 457–474
Majorian (Julius Valerius Majorianus) West only 457–461
Libius Severus (Libius Severianus Severus) West only 461–467
Anthemius (Procopius Anthemius) West only 467–472
Olybrius (Anicius Olybrius) West only 472
Glycerius West only 473–474
Julius Nepos West only 474–475
Leo II East only 474
Zeno East only 474–491
Romulus Augustulus (Flavius Momyllus Romulus Augustulus) West only 475–476

Law and order had vanished from the Roman state when its ruling aristocrats refused to curb their individual ambitions, when the most corrupt and violent persons could gain protection for their crimes by promising their support to the ambitious, and when the ambitious and the violent together could thus transform a republic based on disciplined liberty into a turbulent cockpit of murderous rivalries. Good government depended on limits being set to unrestrained aspirations, and Octavian was in a position to impose them. But his military might, though sufficiently strong in 31 bc to guarantee orderly political processes, was itself incompatible with them; nor did he relish the role of military despot. The fate of Julius Caesar, an eagerness to acquire political respectability, and his own esteem for ancestral custom combined to dissuade Octavian from it. He wished to be, in his own words, “the author of the best civilian government possible.” His problem was to regularize his own position so as to make it generally acceptable, without simultaneously reopening the door to violent lawlessness. His pragmatic responses not only ensured stability and continuity but also respected republican forms and traditions so far as possible.

Large-scale demobilization allayed people’s fears; regular consular elections raised their hopes. In 29–28 bc Octavian carried out, with Marcus Vipsanius Agrippa, his powerful deputy, the first census of the Roman people since 70; and this involved drawing up an electoral roll for the Centuriate Assembly. Elections followed, and Octavian was inevitably chosen consul. Then, on Jan. 13, 27 bc, he offered to lay down his powers. The Roman Senate rejected this proposal, charging him instead to administer (besides Egypt) Spain, Gaul, and Syria for the next 10 years, while it itself was to supervise the rest of the empire. Three days later, among other honours, it bestowed upon him the name by which he has ever since been known, Augustus.

As most of the troops still under arms were in the regions entrusted to Augustus’ charge, the arrangements of 27 bc hardly affected his military strength. Moreover, so long as he was consul (he was reelected every year until 23 bc), he was civilian head of government as well. In other words, he was still preeminent and all-powerful, even if he had, in his own words, placed the res publica at the disposal of the Senate and the Roman people. Augustus particularly wished to conciliate the senatorial class, without whose cooperation civilian government was impossible. But his monopolization of the consulship offended the Senate, making a different arrangement clearly necessary. Accordingly, in 23 Augustus made a change; he vacated the consulship and never held it again (except momentarily in 5 bc and again in 2 bc, for a limited, specific purpose). In its place he received the tribunician power (tribunicia potestas). He could not become an actual plebeian tribune, because Julius Caesar’s action of making him a patrician had disqualified him for the office. But he could acquire the rights and privileges pertaining to the office; and they were conferred upon him, apparently by the Senate, whose action was then ratified by the popular assembly. He had already been enjoying some of a tribune’s privileges since 36; but he now acquired them all and even some additional ones, such as the right to convene the Senate whenever he chose and to enjoy priority in bringing business before it. Through his tribunician power he could also summon the popular assembly and participate fully in its proceedings. Clearly, although no longer consul, he still retained the legal right to authority in civilian affairs.

The arrangement of 23 entailed an additional advantage. The power of the plebeian tribune was traditionally associated with the protection of citizens, and Augustus’ acquisition of it was therefore unlikely to rouse resentment. Indeed, Augustus thenceforth shrewdly propagated the notion that, if his position in the state was exceptional (which it clearly was), it was precisely because of his tribunician power. Although he held it for only one year at a time, it was indefinitely renewable and was pronounced his for life. Thus, it was both annual and perpetual and was a suitable vehicle for numbering the years of his supremacy. His era (and this is true also of later emperors) was counted officially from the year when he acquired the tribunician power.

The year 23 likewise clarified the legal basis for Augustus’ control of his provincia (the region under his jurisdiction) and its armed forces. The Senate invested him with an imperium proconsulare (governorship and high command), and, while this had a time limit, it was automatically renewed whenever it lapsed (usually every 10 years). This proconsular imperium, furthermore, was pronounced valid inside Italy, even inside Rome and the pomerium (the boundary within which only Roman gods could be worshiped and civil magistrates rule), and it was superior (majus) to the imperium of any other proconsul. Thus, Augustus could intervene legally in any province, even in one entrusted to someone else.

The network of favours owed him that Augustus had cultivated within the state, among people of the greatest authority over their own networks, made his position virtually unassailable, but he avoided provoking this high class of his supporters, senatorial and equestrian, by not drawing attention to the most novel and autocratic of the many grants of power he had received, the imperium proconsulare majus. Instead, he paraded the tribunician power as the expression of his supreme position in the state.

After 23 no fundamental change in Augustus’ position occurred. He felt no need to hold offices that in republican times would have conferred exceptional power (e.g., dictatorship, lifetime censorship, or regular consulship), even though these were offered him. Honours, of course, came his way: in 19 bc he received some consular rights and prerogatives, presumably to ensure that his imperium was in no particular inferior to a consul’s; in 12, when Lepidus died, he became pontifex maximus (he had long since been elected into all of the priestly colleges); in 8 bc the 8th month of the year was named after him; in 2 bc he was designated pater patriae (“father of his country”), a distinction that he particularly esteemed because it suggested that he was to all Romans what a paterfamilias was to his own household. He also accepted special commissions from time to time: e.g., the supervision of the supply of grain and water, the maintenance of public buildings (including temples), the regulation of the Tiber, the superintendence of the police and fire-fighting services, and the upkeep of Italy’s roads. Such behaviour advertised his will and capacity to improve the lives of people dependent on him. Of that capacity, manifest on a grand scale, his tribunician power and proconsular imperium were only the formal expression. He was a charismatic leader of unrivaled prestige (auctoritas), whose merest suggestions were binding.

Like an ordinary Roman, he contented himself with three names. His, however, Imperator Caesar Augustus, were absolutely unique, with a magic all their own that caused all later emperors to appropriate them, at first selectively but after ad 69 in their entirety. Thereby they became titles, reserved for the emperor (or, in the case of the name Caesar, for his heir apparent); from them derive the titles emperor, kaiser, and tsar. Yet, as used by Augustus and his first four successors, the words Imperator Caesar Augustus were names, not titles—that is, respectively, praenomen, nomen (in effect), and cognomen. One title that Augustus did have was princeps (prince); this, however, was unofficial—a mere popular label, meaning Rome’s first citizen—and government documents such as inscriptions or coins do not apply it to Augustus. But because of it the system of government he devised is called the principate.

Chatbot answers are created from Britannica articles using AI. This is a beta feature. AI answers may contain errors. Please verify important information using Britannica articles. About Britannica AI.
Britannica Chatbot logo

Britannica Chatbot

Chatbot answers are created from Britannica articles using AI. This is a beta feature. AI answers may contain errors. Please verify important information using Britannica articles. About Britannica AI.

The Roman Senate and the urban magistracies

Augustus regarded the Senate, whose leading member (princeps senatus) he had become in 28, as a body with important functions; it heard fewer overseas embassies than formerly, but otherwise its dignity and authority seemed unimpaired; its members filled the highest offices; its decrees, although not formally called laws, were just as binding; it soon became a high court, whose verdicts were unappealable; it supervised the older provinces and nominally the state finances as well, and it also in effect elected the urban magistrates; formally, even the emperor’s powers derived from the Senate. Nevertheless, it lacked real power. Its provinces contained few troops (and by ad 40 it had ceased to control even these few). Hence, it could hardly dispute Augustus’ wishes. In fact, real power rested with Augustus, who superintended state finances and above all controlled membership in the Senate; every senator’s career depended on his goodwill. But he valued the Senate as the repository of the true Roman spirit and traditions and as the body representing public opinion. He was considerate toward it, shrewdly anticipated its reactions, and generally avoided contention with it. He regularly kept it informed about his activities; and an imperial council (Consilium Principis), which he consulted on matters of policy, in the manner of a republican magistrate seeking the opinion of his advisory committee, consisted of the consuls, certain other magistrates, and 15 senators—not handpicked by him but chosen by lot every six months.

To rid the Senate of unworthy members, he reduced its numbers by successive reviews to about 600 (from the triumviral 1,000 or more). Sons of senators and men of good repute and substance who had served in the army and the vigintiviri (“board of twenty,” minor magistracy) could become members by being elected, at age 25 or over, to the quaestorship. Their subsequent rank in the Senate depended on what other magistracies they managed to win; these were, in ascending order, the aedileship (or plebeian tribunate), the praetorship, and the consulship. No one disliked by Augustus could expect to reach any of them, while anyone whom he nominated or endorsed was sure of election. Despite the emperor’s control, there were usually enough candidates for keen contests. By ad 5 destinatio seems to have been the practice—that is, a special panel of senators and equites selected the praetors and consuls, and the comitia centuriata automatically ratified their choice. In about ad 5, likewise, the consulship was shortened to six months. This not only gratified senators and increased the number of high-ranking qualified officials but also showed that the consuls’ duties were becoming largely ceremonial. This was also true, but to a far lesser degree, of the other unpaid magistrates. A senator really made his mark in between his magistracies, when he served in important salaried posts, military or civilian or both, sometimes far from Rome.

The equestrian order

Senators, however, were either too proud or too few to fill all the posts. Some posts were considered menial and went to the emperor’s freedmen or slaves. Others were entrusted to equites, and the equestrian order soon developed into one of the great institutions of the empire. Augustus decided that membership in the order should be open to Roman citizens of means and reputation but not necessarily of good birth. Ultimately, there were thousands of equites throughout the empire. Although this was a lower aristocracy, a good career was available to them. After tours of duty as an army officer (the so-called militiae equestres), an aspiring eques might serve as the emperor’s agent (procurator) in various capacities and eventually become one of the powerful prefects (of the fleet, of the vigiles, or fire brigade, of the grain supply, of Egypt, or of the Praetorian Guard). This kind of an equestrian career became standardized only under Claudius I; but Augustus began the system and, by his use of equites in responsible posts, founded the imperial civil service, which later was headed chiefly by them. The equites also performed another function: the senatorial order had difficulty in maintaining its numbers from its own ranks and depended on recruitment from below, which meant from the equestrian order. Because this order was not confined to Rome or even to Italy, the Senate gradually acquired a non-Italian element. The western provinces were already supplying senators under Augustus.

Administration of Rome and Italy

Ordinary Roman citizens who were neither senators nor equites were of lesser consequence. Although still used, the old formula senatus populusque Romanus (“the Senate and the Roman people”) had changed its meaning: in effect, its populusque Romanus portion now meant “the emperor.” The “Roman people” had become the “Italian people,” and it was embodied in the person of Augustus, himself the native of an Italian town. To reduce the risk of popular demonstrations in Rome, the emperor provided grain doles, occasional donatives, and various entertainments; but he allowed the populace no real power. After ad 5 the Roman people’s participation in public life consisted in the formality of holding occasional assemblies to ratify decisions made elsewhere. Ultimately, this caused the distinction between the Roman citizens of Italy and the provincial inhabitants of the overseas empire to disappear; under Augustus, however, the primacy of Italy was insistently emphasized.

Indeed, Italy and justice for its inhabitants were Augustus’ first cares. Arbitrary triumviral legislation was pronounced invalid after 29 bc, and ordinary Roman citizens everywhere had access to Augustus’ own court of appeal (his appellate jurisdiction dated from 30 bc and in effect replaced the republican appeal to the people). His praetorian and urban cohorts provided physical security; his officials assured grain supplies; and he himself, with help from such aides as Agrippa, monumentalized Italian towns. The numerous Augustan structures in Italy and Rome (as he boasted, a city of brick before his time and of marble afterward) have mostly perished, but impressive ruins survive (e.g., aqueduct, forum, and mausoleum in Rome; bridge at Narni; arch at Fano; gate at Perugia). Doubtless their construction alleviated unemployment, especially among the proletariat at Rome. But economic considerations did not influence Augustus’ policies much (customs tariffs, for instance, were for fiscal, not protective, purposes), nor did he build harbour works at Ostia, Rome’s port. Italian commerce and industry—notably fine pottery, the so-called terra sigillata, and wine—nevertheless flourished in the conditions he created. Public finances, mints, and coinage issues, chaotic before him, were placed on a sound basis, partly by the introduction of a sales tax and of a new levy (inheritance taxes) on Roman citizens—who hitherto had been subject only to harbour dues and manumission (see below) charges—and partly by means of repeated subventions to the public treasury (aerarium Saturni) from Augustus’ own enormous private resources (patrimonium Caesaris). His many highways also contributed to Italy’s economic betterment.

Augustus’ great achievement in Italy, however, was to restore morale and unify the country. The violence and self-aggrandizement of the 1st century bc had bred apathy and corruption. To reawaken a sense of responsibility, especially in official and administrative circles, Augustus reaffirmed traditional Italian virtues (by laws aimed against adultery, by strengthening family ties, and by stimulating the birth rate) and revived ancestral religion (by repairing temples, building new shrines, and reactivating moribund cults and rituals). To infuse fresh blood and energy into disillusioned Roman society, he promoted the assimilation of Italy: the elite of its municipal towns entered the Roman Senate, and Italy became firmly one with Rome. To keep the citizen body pure, he made manumission of slaves difficult, and from those irregularly manumitted he withheld the citizenship.

Administration of the provinces

Sharply distinguished from Italy were the provinces of the empire. From 27 bc on they were of two types. The Senate supervised the long-established ones, the so-called public provinces: their governors were chosen by lot, usually served for a year, commanded no troops, and were called proconsuls (although only those superintending Asia and Africa were in fact former consuls, the others being former praetors). The emperor supervised all other provinces, and collectively they made up his provincia: he appointed their governors, and these served at his pleasure, none with the title of proconsul because in his own provincia proconsular imperium was wielded by him alone. These imperial provinces might be “unarmed,” but many of them were garrisoned, some quite heavily. Those containing more than one legion were entrusted to former consuls and those with a legion or less to former praetors; in both cases their governors were called legati Augusti pro praetore (“legates of Augustus with authority of a praetor”). There were also some imperial provinces governed not by senators but by equites (usually styled procurators but sometimes prefects); Judaea at the time of Christ’s crucifixion was such an equestrian province, Pontius Pilate being its governor. An entirely exceptional imperial province was Egypt, so jealously guarded that no senator could visit it without express permission; its prefect was unique in being an equestrian in command of legions.

The provinces paid tribute, which helped to pay for the armed services, various benefactions to supporters, a growing palace staff, and the public-works programs. Periodical censuses, carefully listing provincial resources, provided the basis for the two direct taxes: tributum soli, exacted from occupiers of provincial soil, and tributum capitis, paid on other forms of property (it was not a poll tax, except in Egypt and in certain backward areas). In addition, the provinces paid indirect taxes, such as harbour dues. In imperial provinces the direct taxes (tributa) were paid to the emperor’s procurator, an equestrian official largely independent of the governor. In senatorial provinces, quaestors supervised the finances; but, increasingly, imperial procurators also appeared. The indirect taxes (vectigalia) were still collected by publicani, who were now much more rigorously controlled and gradually replaced by imperial civil servants.

To reward his troops after faithful service, Caesar had settled them on lands mostly in the provinces, in veteran towns; and Augustus, for the same reason and to reduce the dangerous military presence in the state generally, resorted to the same procedure on a vast scale. Thus, in the space of a single generation, more than 120 new centres were organized across the empire in an explosion of urbanizing energy never equaled or even approached in later times. In the settlements called coloniae all residents were to be Roman citizens, and the form of government and many other aspects of life specified in their charters bore a thoroughly Roman character. Some coloniae, in further approximation to Italian models, enjoyed exemption from tribute. In the municipia only persons elected as magistrates were awarded Roman citizenship (after Hadrian, in Africa, admission was sometimes extended to the whole of the local senate); but the whole of the local aristocracy in the course of time would be in this way gradually incorporated fully into the state. In municipia, too, charters specified Roman forms of government. Urban centres that were wholly noncitizen, called civitates, enjoyed autonomy in their own affairs, under the governor’s eye; they paid taxes and administered the rural territory around them. In the west, many of them were eventually granted the status of municipia, and they adopted the originally Italian magistracies (duoviri and aediles, collectively quattuorviri) and senate (curia or ordo), normally numbering 100 members. The entire West rapidly came under the administration of urban centres of these three forms, without which the central government could never have done its job. Moreover, these centres radiated economic and cultural influence around them and so had an immense effect, particularly on the way of life of the more backward areas. In the east, however, urban centres, though equally important for government purposes, had already been in existence and long settled into their own culture and forms of government.

The provinces were generally better off under the empire. Appointment over them as governor was now and henceforth generally granted with the emperor’s approval. Because he thought of himself as in some ways the patron and defender of the provincial population, lax or extortionate officials could expect some loss of imperial favour, an end to their careers, or an even more severe punishment.

Emperor worship

For this priceless gift of peace many individuals and even whole communities, in Italy and elsewhere, expressed their thanks spontaneously by worshiping Augustus and his family. Emperor worship was also encouraged officially, however, as a focus of common loyalty for the polyglot empire. In the provinces, to emphasize the superiority of Italy, the official cult was dedicated to Roma et Augustus; to celebrate it, representatives from provincial communities or groups of communities met in an assembly (Consilium Provinciae), which incidentally might air grievances as well as satisfactions. (This system began in the Greek-speaking provinces, long used to wooing their rulers with divine honours. It penetrated the west only slowly, but from 12 bc an assembly for the three imperial Gallic provinces existed at Lugdunum.) In Italy the official cult was to the genius Augusti (the life spirit of his family); it was coupled in Rome with the Lares Compitales (the spirits of his ancestors). Its principal custodians (seviri Augustales) were normally freedmen. Both the Senate and the emperor had central control over the institution. The Senate could withhold a vote of posthumous deification, and the emperor could acknowledge or refuse provincial initiatives in the establishment of emperor worship, in the construction for it, or in its liturgical details. The energy, however, that infused emperor worship was to be found almost wholly among the local nobilities.

The army

It was Augustus’ soldiers, however, not his worshipers, who made him all-powerful. Their allegiance, like the name Caesar, was inherited from his “father,” the deified Julius. The allegiance was to the emperor personally, through a military oath taken in his name every January 1; and the soldiers owed it after his death to his son or chosen successor. This preference of theirs for legitimacy could not be ignored because they were now a standing army, something that the republic had lacked. Demobilization reduced the 60 legions of Actium to 28, a number hardly sufficient but all that Augustus’ prudence or economy would countenance. These became permanent formations, each with its own number and name; the soldiers serving in them were called legionaries. Besides the legionaries there was a somewhat smaller body of auxiliaries, or supporting troops. The two corps together numbered more than a quarter of a million men. To them must be added the garrison of Italy—the praetorian cohorts, or emperor’s bodyguard, about 10,000 strong—and the marines of the imperial fleet, which had its main headquarters at Misenum and Ravenna in Italy and subsidiary stations and flotillas on seas and rivers elsewhere (the marines, however, were not reckoned good combat forces). All these troops were long-service professionals—the praetorians serving 16 years; legionaries, 20; auxiliaries, 25; and marines, 28—with differing pay scales, the praetorians’ being the highest. In addition to their pay, the men received donatives, shares of booty, and retirement bonuses from a special treasury (aerarium militare) established in ad 6 and maintained out of the sales tax and Roman citizens’ death duties. Under Augustus the praetorians were normally Italians, but many legionaries and virtually all auxiliaries were provincials, mainly from the imperial provinces in the west, the legionaries coming from municipal towns and the auxiliaries from tribal areas. The tendency to use provincials grew, and by the year 100 the Roman imperial army was overwhelmingly non-Italian. Nevertheless, it helped greatly to Romanize the empire. The legionaries were Roman citizens from the day they enlisted, if not before, and the auxiliaries (after Claudius anyway) from the day they were discharged; and, though serving soldiers could not legally marry, many had mistresses whose children often became Roman citizens. The troops, other than praetorians and marines, passed their years of service in the “armed” imperial provinces—the auxiliaries in forts near the frontier and the legionaries at some distance from it in camps that showed an increasing tendency, especially after ad 69, to become permanent (some of them, indeed, developed into great European cities). There was no central reserve, because, although desirable for emergencies, it might prove dangerous in peacetime.

The officers were naturally Roman citizens. In the legions those of the highest rank (legati and tribuni) were senators or equites; lower officers (centuriones) might enter directly from Italian or provincial municipalities or might rise through the ranks; by the time they retired, if not sooner, many of them were equites. In the auxiliaries the unit commanders (praefecti) were equites, often of provincial birth. On retirement the soldiers frequently settled in the provinces where they had served, made friends, and perhaps acquired families. Imperial policy favoured this practice. Thus the army, which had done much to introduce into the provinces Romans of all ranks, with their own way of life, through veteran settlements of the 40s, 30s, and 20s bc, continued in the same role on a more modest and casual scale throughout the Augustan reign and for two centuries or so afterward.

Foreign policy

After Actium and on two other occasions, Augustus solemnly closed the gates of the shrine of Janus (a gesture of peace) to show that Rome had peace as well as a princeps. These well-publicized gestures were purely temporary; the gates were swiftly reopened. His proconsular imperium made Augustus the arbiter of peace and war, and an ostensible search for defensible frontiers made his a very warlike reign. While the republic had left the limits of Roman territorial claims rather vague and indefinite, he planned conquests stretching to the boundaries defined by nature (deserts, rivers, and ocean shores), not always, however, with immediate annexation in mind. When annexation did occur, it was followed by the construction of solidly built military roads, paved with thick stone blocks: these also served the official post system (cursus publicus) and were provided with rest stages and overnight lodges at regular intervals.

Areas where subjugation looked arduous and where Romanization seemed problematic were left to client kings, dependent on the emperor’s support and goodwill and under obligation to render military aid to Rome. Such satellite kingdoms spared Augustus the trouble and expense of maintaining strong defenses everywhere; nevertheless, their ultimate and intended destiny was incorporation as soon as it suited their overlord’s convenience. Usually, territory was gained more easily by creating and subsequently incorporating a client kingdom than by launching an expansionist war.

In the south, Augustus found suitable frontiers quickly. In 25 bc an expedition under Aelius Gallus opened the Red Sea to Roman use and simultaneously revealed the Arabian Desert as an unsurpassed and, indeed, unsurpassable boundary. The same year Gaius Petronius, the prefect of Egypt, tightened Rome’s grip as far as the First Cataract and established a broad military zone beyond it. The vast region north of the Sahara and the Atlas Mountains was also secured (c. 25) after a series of punitive raids against native tribes and the annexation of one client kingdom (Numidia) and the creation of another (Mauretania). Three legions, two in Egypt and one in Africa (a senatorial province), policed the southern shore of the Mediterranean.

In the west, consolidation was extended to the Atlantic. Gaul, Julius Caesar’s conquest, was organized as four provinces: senatorial Narbonensis and the imperial three Gauls (Aquitania, Belgica, and Lugdunensis). In Spain, after Agrippa successfully ended in 19 bc the last campaign that Augustus had launched in person in 26, three provinces were formed: senatorial Baetica and imperial Lusitania and Tarraconensis. Three legions enforced Roman authority from Gibraltar to the mouth of the Rhine. Augustus ignored the advice of court poets and others to advance still farther and annex Britain.

In the east, Parthia had demonstrated its power against Crassus and Antony, and Augustus proceeded warily. He retained Antony’s ring of buffer client kingdoms, although he incorporated some, including the most celebrated of them, Judaea; he made it a province in ad 6, respecting, however, some of the customs of its Jewish inhabitants. Augustus stationed four legions in Syria and obviously envisaged the Euphrates River and the northern extension of the Arabian Desert as the desirable frontier with Mesopotamia. Farther north, however, no such natural line existed. North of the Black Sea the client kingdom of the Cimmerian Bosporus, under its successive rulers Asander and Polemo, helped to contain southward and westward thrusts by the Scythians, an Iranian people related to the Parthians, and this provided protection in the north for Anatolia and its provinces (senatorial Asia and Bithynia-Pontus and imperial Cilicia and Galatia, the latter a large new province created in 25 bc out of Amyntas’ client kingdom). By a show of force, Augustus’ stepson Tiberius, in 20 bc, recovered the standards lost at Carrhae and installed Tigranes as client king of Armenia. Although Augustan propaganda depicted this as a famous victory, strategic considerations inevitably obliged the Parthians, once they settled their internal, dynastic dissensions, to dispute Roman control of Armenia. Thus it can hardly be said that Augustus settled the eastern frontier. Missions were sent to the East repeatedly (Agrippa, 17–13 bc; Gaius Caesar, ad 1–4; Germanicus, 18–19), and Armenia remained a problem for Augustus’ successors: Tiberius successfully maintained Roman influence there, but Gaius and Claudius failed to do so, leaving Nero with a difficult situation.

In the north, too, there was difficulty. The Alps and their passes were finally subjugated early in Augustus’ reign. This enabled Tiberius and his brother Drusus between 16 and 8 bc to conquer all the way to the great rivers of central Europe. New provinces were created in the Alps and Tyrol (Maritime and Pennine Alps, Raetia, Noricum) and also farther east (Pannonia, Moesia). Stability along the Danube was precariously maintained, under Augustus and later, by means of periodical alliances with Maroboduus and his successors, who ruled Germanic tribes such as the Marcomanni and Quadi in Bohemia to the north of the river, and by the existence of a Thracian client kingdom to the south of its lowest course. The push across the Rhine began in 12 bc; although it reached the Elbe, consolidation beyond the Rhine proved elusive. A revolt in Pannonia (ad 6–9) interrupted it, and, in ad 9, German tribes under Arminius annihilated Quinctilius Varus and three legions in the Teutoburg Forest. This disaster reduced the number of legions to 25 (it did not reach 28 again until half a century later), and it disheartened Augustus. Old and weary, he withdrew to the Rhine and decided against all further expansion, a policy he urged upon his successor. For the watch on the Rhine the military districts of Upper and Lower Germany were created, containing eight legions between them. Another seven garrisoned the Danubian provinces. These figures reveal imperial anxiety for the northern frontier.

Economic life

Although widespread, Augustus’ wars chiefly affected the frontier districts. Elsewhere, peace prevailed. Indeed, never before had so large an area been free of war for so long. This state of affairs helped trade. The suppression of piracy and the use of military roads, which the frontier warfare itself brought into being, provided safe arteries of commerce. Stable currency also aided economic growth. Activity directly connected with the soil predominated; but there were also many establishments, usually small, engaged in manufacturing, and such products as textiles, pottery, tiles, and papyrus were turned out in surprising quantities. Advanced techniques were also known: glassblowing, for example, dates from the Augustan age. Most products were consumed locally, but the specialties or monopolies from any region usually exceeded local needs, and the surplus was sold elsewhere, generating a brisk interchange of goods. Some traveled great distances, even beyond the empire: trade with India, for example, reached respectable proportions once the nature of the monsoon was understood, and the Red Sea was opened to Roman shipping. Merchants, especially Levantines, traveled everywhere, and fairs were frequent. The Mediterranean world was linked together as never before, and standardization made considerable headway. In Augustus’ day Italy was economically the most important part of the empire. It could afford to import on a large scale, thanks partly to provincial tribute but above all to its own large productivity. The eastern provinces, for their part, recovered rapidly from the depredations of the civil wars and were industrially quite advanced. The other provinces were less developed, but they soon ceased being mere suppliers of raw materials; they learned to exploit their natural resources by using new techniques and then began overtaking the more advanced economies of Italy and the Greek-speaking regions. The importance of trade in unifying the empire should not be underestimated.