Explanations for Roman expansion tend to stress either internal or external factors. Internal factors include the variety of political and economic pressures that made Romans take opportunities for conflict when they presented themselves. External factors include actual threats (both real and imagined), but also the political configuration of the world into which Rome expanded. Naturally internal and external factors interacted, the external environment shaping the evolution of Roman society as it sought ways to out-compete its rivals and in turn the internal dynamics of Roman society impacting on the wider world. Over time, Rome behaved less and less like other states, for example by dropping the conventional diplomatic language with which it first of all presented itself to the Greeks. The more powerful Rome became the more it shaped the world it had to deal with.
Let us begin with internal factors. I have already described how Rome became hooked on annual warfare probably during the fifth century
BC
. The attraction of booty and prestige is obvious; both could be represented as in the interests of the community as well as of the individuals concerned. But this is not a sufficient explanation for Roman imperialism since many ancient states were geared to frequent warfare, and very few became hegemonic powers. It was the structure of alliances built up from the fourth century that locked Rome into expansion. The process had its own outward dynamic. It was not simply that the Romans could only exercise their leadership by summoning the allies to fight alongside them: the more peoples were reduced to allied status, the further away from Rome potential enemies came to be located. There are many parallels for
such a process, from the imperial expansions of the ancient Near East to those of the New World empires of the Aztecs and the Inka.
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Meanwhile Roman institutions, Roman ideology, and even Roman religion were progressively adapted to incremental expansion.
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I described already how it was institutions—not technology or motivation or resources—that gave Rome its comparative advantage over its earliest enemies. But those institutions—the sequence of triumphs, the aristocratic families tending their ancestors’ victory temples, the frequent distributions of booty and especially of land—raised expectations. Once again there is a close parallel with the success of the Qin state in contemporary China, one among a group of rival kingdoms in what is known as the Warring States Period, which had in the fourth century
BC
developed a powerful set of administrative and agrarian systems, and the ideologies to accompany them that enabled it to mobilize land and population much more effectively than its rivals. Qin expansion too involved drawing on the resources of the conquered and programmes of settlement, and culminated in 221
BC
in the creation of the first unified empire.
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Unlike Rome, however, it then faced no external rivals of equivalent power.
Rome emerged from Italy into a hostile world. Stopping expansion after the defeat of Pyrrhus might have been possible—after all, Augustus would later be able to stop the much bigger juggernaut of late first-century expansion—but only if Italy been a remote island. The presence of Carthage close at hand, and the anarchic politics of the eastern Mediterranean, required the expansionist dynamic to be stepped up, not wound down. By the time Rome and her allies faced no serious competition within Italy, their future rivals were already watching them with apprehension. The wars with Carthage, Macedon, and Syria were of a different nature from any that Rome had fought within Italy. They were larger in scale, were sometimes fought on multiple fronts, and once started they were difficult to disengage from until a decisive victory had been won. The Punic Wars threatened Rome with much more than humiliation in the event of defeat. Hannibal was quite successful in detaching some allies from Rome. Signs of the seriousness with which the Senate treated Hannibal’s victory at Cannae in 216 included a collection of almost all gold jewellery from Roman matrons, and apparently also the live burial of a Gallic couple and a Greek couple in the Roman forum. The kingdoms of the east were also serious opponents. When Antiochus III invaded Greece in 191 he was making an explicit challenge to Roman hegemony
in the Balkans. Like Pyrrhus, he saw himself following in the steps of Alexander, but his resources were vastly greater. His kingdom stretched to the border of modern Pakistan. He had personally defeated rebellions in its eastern provinces and Anatolia, had won back southern Syria and Asia Minor from Egypt, and conquered Armenia and Afghanistan. Rome, in other words, was faced with genuine and major threats in the late third and early second centuries
BC
.
The result was a transformation of Roman warfare and the way Romans managed their hegemony. For a start the number of legions levied each year increased significantly, being reduced in the 160s only after the defeats of Carthage, Macedon, and Syria, the completion of the conquest of Italy, and major advances in Spain. Back in the fourth century it had generally been possible to confine warfare to a short summer campaigning season, allowing generals to revert to being civil magistrates and soldiers to working their farms at other times of the year. That alternation came under increasing pressure as some wars grew in scale and length, and as theatres of war were increasingly located further and further from Rome. Rome found herself fighting Carthage by sea in the third century, and the second-century wars in Spain and the Balkans required generals to lead out armies that might not return for years. Magistrates could not always command distant armies along with all their other duties. The Roman elite, innovative as ever, developed new ways of managing warfare. Former magistrates, and sometimes just experienced leaders, were increasingly given commands, and some were extended year after year. Generals operating overseas had to be allowed greater freedom of action too, to decide in effect on war and peace within only fairly broad parameters set by their initial commands.
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The armies they commanded were also changing. The core of a Roman army remained its citizen levies until the reign of Augustus, but in terms of equipment, tactics, and support troops it was in constant evolution. City-state warfare in the classical Mediterranean had been conducted between bodies of heavy armed spearmen, formed up in the formation called a
phalanx
and supported by small numbers of missile troops and lightly armed cavalry. Greeks, Romans, Carthaginians, Etruscans, and Campanians all fielded different versions of this kind of army in the fifth and fourth centuries
BC
. Armies grew more complex when warfare came to involve populations who fought in other ways, as did Gauls, Samnites, Thracians, Iberians, Numidians, and so on. Not only did the emergent imperial powers have to be able to deal more flexibly with their opponents: they were increasingly
able to draw on conquered or allied populations or else hire mercenaries to supplement heavy armed infantry. Carthaginians and Romans alike relied on a wide range of troop types on the battlefield. The Greek armies used by Macedon, Syria, and Egypt were also supported by cavalry, light infantry, and missile troops, in their case supporting a phalanx that employed very long pikes. Between the fourth and second centuries
BC
, the core of the Roman army was transformed from a phalanx of spearmen to a body of heavily armed troops equipped with heavy javelins and swords. A variety of smaller tactical units were developed, in particular the maniple of around 120 men and the cohort of around 400. The flexibility allowed by these systems and weapons gave Roman armies some advantages over both the phalanx of Greek armies (as happened at Cynoscephalae) and less well-equipped opponents like the Gauls.
Empire’s Rewards and the Cost of Empire
Meanwhile the economics of hegemony became more complex. Apart from booty and initial confiscation of land, Rome regularly extracted only levies of manpower from her defeated Italian enemies. Carthage and the kings could be made to pay indemnities extended over decades to provide the Roman state with a regular income. That income was largely spent funding grandiose building in the capital.
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Building works were contracted out by the censors to Roman citizens, who in this way shared in the proceeds of empire. Polybius was struck by the scale of this operation.
The people are subordinated to the Senate and must defer to them both collectively and also as private individuals. For a very great number of public contracts are issued by the censors for the construction and repair of public works all over Italy. It would not be easy to enumerate them all: and there are also contracts for the management of rivers, of ports, of orchards, of mines and land: in short, all those things that are in the power of the Roman state. The general populace is involved in all these affairs, so much so that one might almost say that everyone has an interest in these contracts and projects. For there are some who bid before the censors in the forum to have the contracts for themselves; others go into partnership with them; some stand surety for the sums involved; while yet others pledge their own wealth to the state for them.
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From the 180s we begin to hear of great construction projects around the forum, spending on the harbours of Rome, and on roads and colonies.
During his censorship Cato the Elder commissioned a vast covered hall for indoor meetings, known grandiosely as the Basilica Porcia after the Royal Stoa (the Stoa Basilike given to Athens by the King of Pergamum). It was funded not from booty or private wealth, but from public revenues. The final defeat of Macedon resulted in a permanent exemption for Roman citizens from direct taxation. From the 160s on the Roman people were, in this sense at least, all beneficiaries of empire. The destruction of Carthage was followed almost immediately by the construction of the magnificent aqueduct known as the Aqua Marcia. Less welcome was the effective end to colonial settlement, a practical consequence of the conquest of Italy linked to a less rational refusal to settle Romans beyond the peninsula. Spending in Rome and the end of colonization helped swell the size of the capital, and so the demand for public works. Rome was now locked into a cycle of urban growth as well as one of imperial expansion.
Indemnities were extracted from rich and complex societies whose economies had been left intact. Like booty, the proceeds were spent mostly in Italy. The needs of armies in the new overseas territories had to be supplied by other means. The cities of Sicily had paid an annual tithe to Syracuse, and Rome appropriated this. Spanish tribes supplied their occupiers first with grain, and then with cash tribute. Roman power over Spain also allowed them to license exploitation of the silver mines around Cartagena (New Carthage), the former Punic capital.
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These origins of a provincial tax system do not seem to follow a grand plan. It was often left to Roman conquerors and generals to devise systems that worked locally, and these were often based on pre-Roman precedents. Fragments of the fiscal systems of Hiero of Syracuse and of the kings of Pergamum survived long into the imperial taxation systems. Wherever locals did not undertake the relevant collection or exploitation themselves, contracts were once again issued to Roman citizens. The attractions of running an empire through public contracts are obvious: the state did not need to create a colonial administration, what risks there might be were borne by private individuals, and a wide circle benefited from the proceeds of victory. Polybius added that their dependence on the Senate and the censors kept those who wanted contracts subservient. But the downsides to public contracting are only too well known today. Contractors took the short-term view, and were prepared to exploit provincial subjects without mercy while they held the contract. The Roman term for a contractor,
publicanus
, is regularly paired with ‘sinners’ in the Gospels.
Rome’s struggles with other Mediterranean hegemonic powers also changed the politics of warfare. Alongside the increased scale of conflict, there appear voices of restraint. Real differences seem to have emerged both in the Senate and the assembly about the advisability of particular wars. The war against Philip V of Macedon was almost headed off in the assembly. Cato the Elder had to badger the Senate for years to finish off Carthage. The destruction of Carthage and Corinth clearly appalled some Romans. One reason Rome’s eastern allies found it difficult to second-guess Roman policy in their region during the second century was that it genuinely was unpredictable. There was a marked resistance to acquiring territory east of the Adriatic, even after Rome had more or less had to create a province in Macedonia in the 140s. When, in 133, Attalus III of Pergamum died leaving his kingdom to Rome, the legacy was only accepted when Tiberius Gracchus took it to the popular assembly and promised that the proceeds would be used to fund renewed land distributions within Italy.
Not all the wars of the late third and early second century were conflicts between great powers. Roman armies fought in Spain and north Italy for much of the period, ventured into the Gallic interior, were drawn into, or provoked, secondary wars in the Balkans and Asia Minor. Generally these wars were less controversial, but occasionally senators complained about wars fought, with no formal authority, against distant peoples; attempts were made to deny triumphs to some of these generals. Generals might well respond that the Senate did not understand the situation on the ground, and some pointed to the proceeds of their victories. Competitive building enriched the monumental fabric of Rome, triumphal festivals, historical dramas, and epics all involved the people in the imperial project. Occasionally, commissions of senators were dispatched to regularize post-campaign settlements, or to inspect colonies. Embassies visited Rome from all sides. It is a sinister sign that in 149
BC
a law court was set up to deal with accusations of corruption by representatives of the Roman state abroad. The leadership of allies under arms had mutated into a different form of imperial rule.