Figure 1.1 Antonine Itinerary as a map of Britain
Before addressing the question posed in the title of this chapter, we must take a short definitional diversion. Over the past few decades, an astonishing number of historians and modern strategic thinkers have tied themselves in knots arguing over whether the concept of strategy even existed before the end of the eighteenth century, when the word “strategy” finally made it into the lexicon. In this rendering, the notion of strategic thinking is a by-product of the Enlightenment, when learned persons placed great faith in man’s ability to understand the world through empirical science and reason. War, the greatest of all human endeavors, was not excepted from this movement. This is really a matter of semantic interest, in much the same way as one can ask whether those who made “Greek fire” were employing chemistry, which was not generally recognized as a science until Antoine Lavoisier published Elements of Chemistry in 1787. Others were certainly thinking about strategy and acting on their ideas long before Enlightenment thinkers began to systematize our mental approaches to the topic.
In any event, strategy is always and everywhere a matter of ends, ways, and means, as seen through the prism of “risk.” Half of the professional strategic thinkers reading this will scoff upon finishing that last sentence. The reasons for doing so are numerous, starting with the accusation that the very simplicity of the “ends, ways, means” paradigm just leaves out too much that is required to develop a firm understanding of the topic.1 Still, the basis of any good model is simplicity, although we must keep in mind that simplicity seldom implies a lack of depth. Einstein’s theory of relativity, for instance, has often been summarized on a postage stamp. In the case of defining strategy, as with E = mc2, the complexity increases the more one ponders the practical realities of strategic thinking and execution.
If we can torture the analogy to Einstein’s theory just a bit further, one might note that, despite its continuing relevance in explaining the macro universe, much of the theory’s elegance has been overthrown by the weird chaos of the quantum world. Similarly, even the best-considered, most well-planned strategy will quickly fall into shambles once confronted by the chaotic challenges of the real world. Thus, the best strategies endure despite chaos because resilience and the capacity for rapid adaption were built into the strategy from the start. As Helmuth von Moltke the Elder, the general most responsible for winning the wars that united Germany into a single state, once said, “Strategy is a matter of expedients that takes it far beyond the realm of mere scholars.”2
Typically, strategy, when applied to the interactions of states, is narrowly defined as the bridge between an established policy and the military aims necessary to achieve it. This is clearly what is meant by the term “military strategy.” But a state’s aims are not always achieved through military force, and a strategy focused entirely upon military affairs, without taking account of the economic, political, social, and diplomatic structures that underpin and support it, is doomed. This broader concept of strategy—commonly referred to as “grand strategy”—seeks to align all the resources and institutions of the state toward specific policy goals. At its highest level, the primary goal of any state is survival. What else a state can accomplish within a strategic global context rests upon the distribution of power within the system and must always be judged in relative terms.
Still, many a large forest has been sacrificed in order to publish works that define strategy, such that there are now thousands of definitions differentiated only by such subtleties that would bewilder Thomas Aquinas and the scholastics who surrounded him. So I am going to offer two sets of definitions. The first are those proposed by my own institution—the Marine Corps War College.
In its simplest form, strategy is a theory on how to achieve a stated goal. . . . Another way to think about strategy is to consider how to get from a current state or condition to a desired state or condition.3
In Joint Publication 3.0—Joint Operations, the Joint Chiefs of Staff offer their definition of strategy.
Strategy—A prudent idea or set of ideas for employing the instruments of national power in a synchronized and integrated fashion to achieve theater, national, and/or multinational objectives.4
American strategists also employ the DIME paradigm in their strategic thinking. DIME is an acronym for the process of integrating a myriad of diplomatic, informational, military, and economic strategies and concerns into a coherent grand strategy aimed at protecting and enhancing our national values and interests.
The interesting thing about strategy is that, like the nature of war, the purposes underlying its methodologies never change. Rome never came up with a fancy acronym for the lists of interests influencing grand strategy. Nor did they ever express their strategic thinking in terms of the “ends, ways, means” mode. But if they were doing any strategic thinking and acting on those thoughts, they were employing precisely these concerns and methods. The crucial question, therefore, is whether the Romans were capable of thinking about the future in strategic terms. This question has riled the field of Roman studies for two generations, and now that we have defined the terms, we can turn to the details of that debate.
In Book 1 of Rhetoric, Aristotle lists the subjects that all politicians and statesmen must be familiar with: “[They are] five in number: ways and means, war and peace, national defense, imports and exports, and legislation.”5 According to Aristotle, policymakers must, as part of mastering “ways and means,” be familiar with the extent of the state’s resources and their sources. Further, they must be thoroughly acquainted with how revenues are being expended by the state so that they are not wasted on superfluous pursuits.6
In terms of war and peace, Aristotle urges politicians to apply themselves to comprehending the extent of a state’s actual and potential military strength, as well as that of enemy states. The philosopher also makes a strong case for the importance of studying military history to comprehend how states have waged war in the past, as well as specifically studying how potential foes have previously waged war. In modern strategy courses this would all be consolidated under ways and means, as would his comments on national defense: “[H]e ought to know all about the methods of defense in actual use, such as the strength and character of the defensive force and the positions of the forts—this last means that he must be well acquainted with the lie of the country—in order that . . . the strategic points may be guarded with special care.”7
Aristotle’s concern with imports and exports would be familiar to any current student enrolled in a strategic studies program, for he emphasizes gaining an appreciation of tracking what and how much is being traded between states—a very modern preoccupation. His prime concern, in this regard, was ensuring that rulers were taxing cargoes leaving and entering ports or crossing borders, a crucial source of revenue. Modern states see this comparison in increasingly mercantilist terms, but the crucial importance of these flows remains the same.
It is when Aristotle discusses legislation that we begin to see hints of Carl von Clausewitz’s trinity—the people, the government, and the military.8 For instance, he addresses the crucial importance of political institutions as a widely accepted legal framework in securing and enhancing the strength of the state.9 Neither Aristotle nor Rome’s ruling elite had a modern understanding of these issues, but they clearly understood their importance. Rome never came close to having perfect institutions—no state in history has ever been so blessed—but when one discusses strategy, what matters is not the perfection of one’s institutions, but rather their relative superiority to rivals in terms of outcomes. Rome offered institutions and a legal structure superior to those of any previously found in the ancient world, and for most of the empire’s existence its institutional framework was far superior to that of any of its competitors. Unfortunately, Rome, at least until Diocletian’s reforms, never truly developed its administrative infrastructure much beyond that required to manage a city-state. But by working with local elites and absorbing their local economic and tax structures into the empire’s greater edifice, Rome’s organizational structure proved sufficient to rule a huge geographical area for nearly half a millennium.
Aristotle’s ideas about what a statesman or policymaker should deeply consider can, with minimal rewording, be used to teach the foundations of strategic thinking in today’s military’s professional education system. If one took these ideas out of context and put them in front of a professor from any military war college, she would immediately recognize them as the underpinnings of all modern strategic thinking. The Romans had a passion for Greek culture and were devoted readers of Aristotle, as well as the histories of Herodotus and Thucydides, all of which would have been absorbed by every educated Roman. These histories are still taught to senior officers in every war college because, along with Aristotle’s writing, they demonstrate a very sophisticated level of strategic thinking.
So, to assume that the Romans were incapable of thinking in strategic terms, one has to believe that somewhere between Aristotle putting his strategic-thinking framework on paper (or papyrus) and the advent of the Roman Empire, educated elites mysteriously lost their capacity to think about statecraft and empire in strategic terms. But this is precisely what the overwhelming numbers of Roman scholars have proposed and accepted since Luttwak published The Grand Strategy of the Roman Empire.10 This historical consensus is elegantly presented in The Cambridge Ancient History:
It is probably incorrect to define Roman military policy in terms of long-term strategical objectives, which saw the emergence of various systems designed to achieve “scientific” defensible frontiers. For one thing, the Romans lacked a high command or government office capable of giving coherent direction to overall strategy, which was therefore left to the decision of individual emperors and their advisers. . . . Military decisions were probably ad hoc, as emperors were forced into temporary defensive measures to limit damage and then counter-attacked when circumstances and resources allowed. . . . In any case, the Romans lacked the kind of intelligence information necessary to make far-reaching, empire-wide decisions. Indeed, they probably did not have a clear-cut view of frontiers, and came slowly to the idea that they should constitute a permanent barrier and form a delineation of Roman territory.11
Take a moment to ponder the meaning of this statement. If it is true, then we must accept that for five hundred years the empire spent as much as four-fifths of its tax revenue on a 450,000-man army; building and maintaining three thousand miles of fortified frontiers (limes), supported by tens of thousands of miles of military roads; and conducted hundreds of prolonged military campaigns—all without anyone ever once stopping to give any thought as to how all of this was put together. Security and war were the empire’s overriding concerns and the primary business of the state. It is unimaginable that they approached such a monumental effort—sustained over five centuries—as a haphazardly constructed afterthought or in an ad hoc fashion. In a crisis, certain decisions may have been ad hoc—as they are today—but they were certainly made within a specific strategic context, which rulers and their counselors grasped and understood.12
Still, despite the obvious logic of the above observations, the overwhelming historical consensus is that Rome did not think in strategic terms, nor was it possible for Romans to do so. Several arguments have been marshaled to make this case, and it is best to take each of these in turn. The first revolves around Roman geographical ignorance and faulty comprehension of the geographical space within the empire and beyond. This debate has already been over-analyzed by modern scholars, but as this topic remains central to any denial of Roman capacity for strategic planning it must be tackled once again, starting with Susan Mattern, who argues: “The Roman view of the geographical world . . . seems at first schematic—that is, simplistic; too simplistic a framework for a complex geopolitical strategy.”13 In this Mattern is following in the footsteps of Benjamin Isaac, who, citing Fergus Millar, wrote that “the Romans did not have a sufficiently clear or accurate notion of topographical realities to allow them to conceive of the overall military situation in global strategic terms.”14 What Rome did have, as Mattern repeatedly states, were itineraries (itineraria) that were used to plan travel from one point to another within the empire. From her perspective, such itineraries were fine for planning a party about to embark on an extended period of travel but useless for military or strategic planning. Isaac amplifies this by stating that it “requires only a glance to determine that such itineraries would be useless to today’s military planners.”15 One wonders, then, why the fourth-century author Vegetius would recommend their use for that specific purpose. As he warns in De Re Militari:
First, he should have thoroughly written out as fully as possible itineraries of all the regions in which the war is being waged, so that he can learn thoroughly the intervals between places, not only regarding the number of miles but even the quality of the roads, and inspect carefully the shortcuts, bypaths, mountains, and rivers, faithfully described; indeed the more prudent generals were fortified by having obtained itineraries of the provinces to which necessity used to take them, which were not only annotated but even drawn.16
By adding “even drawn,” Vegetius is almost certainly describing the creation of maps, of the type many historians believe the Romans did not employ in their military operations. Isaac does comment on Vegetius’s advice that troop movements should be planned by employing itineraia picta but agrees with Mattern that these picture-laden itineraries were of little use in strategic planning.
However, before judging whether itineraries were of any use for strategic planning, it helps to understand what a Roman itinerary looks like and what kinds of information it provided. One of the most famous itineraries, which is still extant, is the Antonine Itinerary (Figure 1.1): a list of place names with notations as to the distance between them. It dates from the third century CE and may have been created for Caracalla’s campaigns in the east.17 Any Roman general with access to this document or anything similar could instantly assess the daily march distances from start to stop, and just as easily calculate the distances along various routes from any point in the empire to any other point. The most famous and best-preserved of these itineraries with pictures is the Tabula Peutingerianna—the Peutinger Map (Figure 1.2).18 This is not just a list of locations and distance, but more like a road map, presenting the information in graphic form. Roads are shown by lines, with the distances between towns and cities notated along each line. In addition to this kind of detailed itinerary, the Romans employed other sources of geographical data, but only a few of these have survived the centuries. The most famous that has come down to us are Strabo’s Geographica, Ptolemy’s Geographia and world map, and the Map of Agrippa—the Orbis Terrarum.19
Figure 1.1 Antonine Itinerary as a map of Britain
Figure 1.2 The Tabula Peutingeriana
Seen through modern eyes, these maps seem to have major problems, and the Roman worldview is certainly not ours. But how Rome saw the world is not the crucial question. Rather, one must ask whether the Romans’ worldview, as well as their geographical tools—itineraries and basic maps—was sufficiently accurate to enable them to plan and execute strategy? Susan Mattern, like most historians, believes it was not: “Modern policy makers would not dream of conducting foreign policy relations or planning a war, much less undertaking one, without accurate scaled maps.”20 This statement is not correct. Maps with the detail and accuracy of the kind most historians declare necessary for the planning of strategy and the conduct of military operations did not really exist until the Austro-Hungarian Empire undertook to map much of Western Europe, a task not completed and published until the eve of World War I.21 Yet no one claims that when Napoleon was crawling over the inferior maps of his era, sometimes bumping heads with his chief cartographer, General Bacler de l’Able, that he was not engaged in strategic campaign planning.22 If adequate maps are the basic foundational necessity for strategic planning, then no state or army was capable of plotting strategy before the modern era. But we find Vegetius advising a Roman general:
If any difficulty arises about the choice of roads, he should procure proper and skillful guides. He should put them under a guard and spare neither promises nor threats to induce them to be faithful. They will acquit themselves well when they know it is impossible to escape and are certain of being rewarded for their fidelity or punished for their perfidy.23
Similarly, Frederick the Great, during the Seven Years’ War (1756–1763), advised his generals that, when seeking intelligence about an area, they should find a rich citizen with a large family and reward him for information, while at the same time promising to hack his family to death before his eyes if he is less than truthful.24 Clearly Frederick, commanding approximately fifteen hundred years after Vegetius wrote his instructions, was still having problems getting accurate maps on which to plan campaigns and battles. Still, no one believes that Frederick or the other generals and statesmen of the era were incapable of strategic planning.
The fact is that Roman itineraries provide exactly the type of information required for strategic planning, particularly in its military dimensions. President Bill Clinton once said, during a visit to the aircraft carrier USS Theodore Roosevelt, “When word of crisis breaks out in Washington, it’s no accident the first question that comes to everyone’s lips is: where is the nearest carrier?”25 Neither Clinton nor the Joint Chiefs had any concern about global geography beyond the distance of the carriers to the crisis area and how long it would take them to make the transit. Henry Kissinger once called aircraft carriers “100,000 tons of diplomacy.” Similarly, Rome’s legions were the “mobile diplomacy” of the empire. In any crisis, there were only three things an emperor needed to know: where the crisis was, how far from the crisis the nearest available legions were, and how long it would take the legions to travel between these two points. Simply put, no emperor had to know a single geographical fact that was not included in the itineraries of the time. In them, an emperor and his advisers would find detailed information about distances for each leg of the legions’ marching route. From that point it was all about assigning commanders, issuing orders for the legions to march, and prepositioning supplies—food and fodder—along the route of the march. This last task was easily accomplished by sending messengers to each stopping point on the itinerary or by the legions sending officers ahead.
Interestingly, while doing some research on the Battle of Yorktown, I came across a map employed by Generals Washington and Rochambeau to move their combined forces from Rhode Island and New York to Yorktown. Like the itinerary-based maps the Romans must have used, the only markings on Washington’s maps were the routes of the march and the planned stopping points each evening. All the geographical space along those routes was a matter of supreme indifference to the Allied commanders and their staffs. And, as the Romans must have done, Washington and Rochambeau sent messengers ahead of the armies whose job was to order food that would be collected along each point listed on the map. In short, the tools available to the Romans were those still being employed nearly two millennia later by generals and statesmen who found them sufficient for their strategic needs. The reality of Roman strategic thinking was that they employed a point-to-point analysis to strategy and crisis resolution. Their primary concern was distances and time. When the need arose to move from point A to point B, the fact that the Alps might be in the way was of little concern. What mattered was the number of days it took to cross the space, whether it was occupied by rolling grasslands, deserts, or mountains.
Interestingly, in the war-gaming world, many designers have discovered that the easiest way to think about and simulate the strategic level of any conflict is through using point-to-point designs (itineraries) that look a lot like the Peutinger Map. One of the best war games simulating Roman strategic issues—Pax Romana—also employs a point-to-point methodology to address how Rome reacted to problems.
What served the Romans well still underpins how today’s generals and statesmen plan and execute military-based strategic endeavors. When planning for crises in any part of the world, almost all military planners start with an analysis of the hubs and nodes that make up the various transport networks. Thus, when planners are told to move military forces halfway across the world, they do not think about maps as most of us would. Rather, they think in terms of networks filled with pathways and nodes where the major variable is the mode of travel—air, land, or sea—and includes basic information, such as how long it takes to go between nodes and the carrying capacity of the vehicles involved. Until the troops are in close contact and fighting, the underlying geographical aspects involved in military operations are barely a consideration. In fact, Systems and Network Centric Warfare, which is based on protecting one’s crucial nodes while wrecking those of an enemy, has now become the basis of almost all military planning.26 Anyone receiving a briefing on current military plans would be struck by the fact that there is no requirement for a geographic map. To strategic planners, all of the geographic features and pretty colors on common maps are nothing but eye candy.
Handed a list of nodes, transit speeds for various modes of travel, and the capacity of each node and pathway to handle traffic, military strategists can deploy the full might of the U.S. military anywhere in the world without ever referencing a geographic map. One can easily see how such information, once set down on paper, begins to look suspiciously like the itineraries the Romans worked with. In short, if a Roman emperor wants to think about future strategy or react to a major crisis in a distant part of the empire, itineraries are the perfect instrument for doing so. Moreover, the Romans, although they never spelled out their approach in manuals, clearly understood the crucial importance of nodes (towns, cities, fortresses, etc.) and paths (the Roman road network, rivers, and the Mediterranean). The evidence, far from indicating that the Romans did not have the geographic tools to think in strategic terms, demonstrates the exact opposite: Rome possessed the precise basic tools that would enable a level of sophisticated strategic thinking comparable to that of the modern era.
Rome’s supposed lack of interest in maps or geographical intelligence has been extended by historians to suggest that they had a dearth of information regarding the empire’s separate theaters of conflict. This would mean that for nearly a thousand years Roman military commanders conducted military campaigns without any knowledge of the local terrain, possible marching routes, or where their enemies might be—that Rome chose simply to plunge into the unknown and hope for the best. This is absurd. Voluminous evidence in the historical record demonstrates that Roman commanders took a tremendous interest in local geography and were fully capable of planning huge campaigns over vast distances. For instance, in 6 CE, Augustus gave his approval for the destruction of the Germanic Marcomanni confederation under its king, Maroboduus. This was no mean undertaking, as many of the tribe’s warriors had at times found employment as Roman auxiliaries and were therefore expertly familiar with Roman methods of war. As Velleius Paterculus, one of Tiberius’s staff officers, states: “The body of guards protecting the kingdom of Maroboduus, which by constant drill had been brought almost to the Roman standard of discipline, soon placed him in a position of power that was dreaded even by our empire.”27
To remove this looming threat, Augustus had his general, Tiberius, the future emperor, mobilize twelve legions and planned a pincer movement from two widely separated provinces. Even conceiving of such a plan, never mind executing the logistics of such a vast enterprise, requires huge amounts of staff work, underpinned by a healthy understanding of the enemy forces, as well as the distances and geography involved. Velleius Paterculus certainly showed a deep knowledge of the threat posed by Maroboduus’s huge, highly trained army as well as of the threat created by the geography of the region:
His army, which he had brought up to the number of seventy thousand foot and four thousand horse. . . . He was also to be feared on this account, that, having Germany at the left and in front of his settlements, Pannonia on the right, and Noricum in the rear of them, he was dreaded by all as one who might at any moment descend upon all. Nor did he permit Italy to be free from concern as regards his growing power, since the summits of the Alps which mark her boundary were not more than two hundred miles distant from his boundary line. Such was the man and such the region that Tiberius Caesar resolved to attack from opposite directions in the course of the coming year. Sentius Saturninus had instructions to lead his legions through the country of the Catti into Boiohaemum, for that is the name of the region occupied by Maroboduus, cutting a passage through the Hercynian forest which bounded the region, while from Carnuntum, the nearest point of Noricum in this direction, he [Tiberius] himself undertook to lead against the Marcomanni the army which was serving in Illyricum.28
This great attack was called off when the legions had to be diverted to put down the Pannonian Revolt (6–9 CE). As a consequence of the Varian Disaster—when three legions were annihilated deep in the German forests in 9 CE—another attack into Marcomanni territory was not contemplated again for over 150 years, during the reign of Marcus Aurelius. Before moving on, it is worth noting another expedition deep into Germany, also led by Tiberius. As recounted by Paterculus:
A Roman army with its standards was led four hundred miles beyond the Rhine as far as the river Elbe, which flows past the territories of the Semnones and the Hermunduri. And with this wonderful combination of careful planning and good fortune on the part of the general, and a close watch upon the seasons, the fleet which had skirted the windings of the sea coast sailed up the Elbe . . . effected a junction with Caesar and the army, bringing with it a great abundance of supplies of all kinds.29
Consider both examples. The first called for one pincer starting from modern Mainz to meet the other arm of the pincer, which started from the great Roman fortress of Carnuntum, well to the east of Vienna. The vast distances involved cover almost the same geographical area as Napoleon’s Ulm-Austerlitz campaign and Wagram campaign—some eighteen hundred years later. The second example is even more remarkable, as it called for coordinating the actions of two forces out of contact with one another—an army fighting its way across hostile territory and a naval force navigating in waters where no Roman fleet had ever sailed. Nearly sixteen hundred years later, in 1588, despite two years of planning, the Spanish Armada, in a similar enterprise in approximately the same region, failed to link up with the Spanish Army of Flanders to invade England. It was not until General William T. Sherman’s army arrived at Savannah, Georgia in 1864 and found a resupply fleet waiting for them that an enterprise of similar scope and hazards was again accomplished by design.30
The point is that neither expedition could be planned, never mind executed, without a huge amount of geographical information and comprehension. Further examples of Roman geographic knowledge and its employment in the conduct of military campaigns litter the ancient literature. This makes one thing certain: the Romans had a thorough grasp of the geography within the bounds of their empire, as well as huge swaths of territory immediately beyond their borders. Moreover, as the two examples above demonstrate, the Romans had a clear idea of the capacity and capabilities of the threats within these regions. That does not mean that surprises, such as the Varian Disaster, were impossible. In truth, Rome was often caught unawares, and Roman armies suffered many embarrassments. But for the most part these were the result of misreading an enemy’s intent, not a lack of knowledge of their capabilities.31
Rome’s supposed lack of geographic knowledge has fed one of the more enduring myths of Roman studies: that they had no idea of a fixed frontier on the other side of which security threats lay, Frontiers instead being simply zones or districts within which Rome managed economic and diplomatic affairs with its neighbors. Two of the greatest authorities on the Roman frontiers have declared that the frontiers—limes—were an administrative concept unconnected with the military structures that might be found within them.32 The historian David Cherry, in The Cambridge Ancient History, neatly sums up where this burgeoning consensus has led: “[N]one of the frontiers appear to have been wholly defensive in purpose, partly also because the Romans themselves do not seem to have considered the frontiers to be either lines of defense or demarcation. It is now widely agreed instead that the frontiers functioned as zones or borderlands.” As far as Cherry is concerned, the Romans themselves never understood that the frontiers behaved militarily or administratively. In this view, there is “little reason to believe that the Roman authorities considered it to be their duty to protect the provincial populations against those who lived beyond the frontiers.” Finally, Cherry maintains that even if the imperial government desired to develop a coherent defensive system of defensive barriers and fortifications, “it is unlikely that it could have overcome the delays of communications and transportation that were a necessary consequence of the vast distances which separated the frontiers from the capital, and from each other.”33 But that is exactly what the Romans did: they overcame vast distances and built an integrated system of defensive structures over thousands of miles of frontiers.
Cherry may represent the consensus of historians, but this view flies in the face of the evidence and common sense. As to the questions of whether the Romans considered the frontiers a defensive barrier, it is probably best to let the Romans speak for themselves. As Aristides wrote:
Beyond the outermost ring of the civilized world, you drew a second line, quite as one does in walling a town. . . . An encamped army like a rampart encloses the civilized world in a ring . . . [defended by] a barrier of men who have never acquired the habit of flight. . . . Such are the parallel harmonies or systems of defense which curve around you, that circle of the fortifications at individual points, and that ring of those who keep watch over the whole world . . . all this one can call a ring and circuit of the walls.34
He is joined by Appian, who wrote: “They surround the empire with great armies, and they garrison the whole stretch of land and sea like a single strong-hold.”35 Herodian, writing in the third century CE, added: “When Augustus established his sole rule, he relieved Italians of their duties and stripped them of their arms. In their place he established a defensive system of forts of the empire . . . as if to act as a barricade for the Roman Empire. He also fortified the empire by hedging it round with major obstacles, rivers and trenches and mountains and deserted areas which were difficult to traverse.”36
While Herodian’s comments are more closely related to the situation in the second century CE than they are to the reign of Augustus, he and the others quoted above clearly envision a Roman Empire protected by a strong defensive system manned by Rome’s legions. A later author, Zosimus, even condemned the Emperor Constantine for weakening this defensive system to man his mobile field armies—the comitatenses—blaming the emperor for adopting measures that gave the barbarians free access to Roman dominions. As Zosimus saw it, Diocletian, by rebuilding the frontier defenses had secured the empire from barbarian invasion; Constantine, however, by removing soldiers from the frontiers, had destroyed that security: “Thus, he stripped the frontiers of protection and by moving the soldiers to interior cities, made the soldiers effeminate by accustoming them to public spectacles and pleasures.”37 Zosimus, a pagan who tended to blame everything that went wrong with the Roman Empire on its first Christian emperor, is likely not the most reliable writer to interpret the reasons and causes of events, but the point here is that his comments, like the others, demonstrate that the Romans undoubtedly believed they possessed a clearly demarcated, heavily fortified, and well-garrisoned frontier that would defend the empire from enemies beyond it.38
Historians looking to deny what the Romans so clearly stated have been forced to make diversionary arguments and increasingly strange assertions. For instance, as the term limes appears to have changed definition several times over the empire’s five hundred years of existence, Isaac uses these changing definitions to claim that we cannot accept that the military installations found along the limes (when they are defined as a line), and throughout the limes (when they are defined as a region) necessarily had a military function.39 Here he is joined by Whittaker, who believes, as a result of having discovered evidence that the Roman fortress of Qasr Bshir in Jordan was employed for civilian administrative purposes, that we have been too quick to describe frontier buildings as defensive installations,40 even though a photograph of Qasr Bshir still clearly shows battle towers and crenellated walls. One wonders why these historians never asked why a purely administrative center would need such stout and costly defenses; surely the location would be just as efficient as an administrative or trading center without them. The expense of such extensive walls can be justified only if they were meant for security.41 Following Whittaker, many historians believe that the Roman frontiers should be thought of more as a zone than a line. In this Whittaker is almost certainly correct; where he goes wrong is his claim that the structures within these zones served to conduct mostly, if not entirely, administrative and economic functions, as if such purposes could not coexist with a military role. After all, most medieval castles and fortresses performed administrative and economic functions, but no one doubts their concurrent role as military installations.
So what are these historians missing? For one, how the definition of limes changed over the centuries is not important. This is a semantic battle that does little to mask actual events on the ground, where it is impossible not to notice that the Romans invested huge sums in constructing a network of walls, fortresses, forts, naval bases, and towers along the entire length of the Rhine and Danube. Because some of these defensive works were not optimally sited, Isaac would have us believe that we cannot divine the true nature of the whole. But we most certainly can do this through the application of a bit of common sense. Walls are built for only two reasons: to keep someone in or to keep someone out. In Rome’s case, these extensive lines of fortifications and supporting infrastructure aimed to stop or delay an invasion force before it could seriously threaten the empire. True, throughout the Roman defensive systems one will, here and there, find a fort that does not appear to have been ideally situated for defensive purposes. All that means is that additional factors must have influenced the location of certain forts and bases. Consider the world today. The United States is littered with well-maintained bases that serve no immediate security need but are located in a powerful politician’s district. Rome was not immune to such pressures.
Isaac holds that the great Danube and Rhine rivers were not barriers and that the Romans never thought of them as such. He claims that they were easily crossed by boats and rafts and thus cannot be considered much of an obstacle. He cites Batavian tribesmen trained to swim the Danube with their weapons as an example of why rivers are not truly natural obstacles in a military sense.42 However, an invading force will need to cross with thousands of troops, pack animals, and wagons.
Pace Isaac, throughout history rivers have presented a natural obstacle, one that works against military movements. That a few exceptional swimmers were trained to cross them scarcely lessens the difficulties that would confront an entire army trying to cross rivers, such as the Rhine and the Danube, that were over a mile wide along most of their course. One should also keep in mind that Roman soldiers were well aware of a crucial point of military doctrine that is still repeatedly drilled into every young military officer: obstacles not covered by troops or firepower are not obstacles. As such, neither the Danube nor the Rhine was ever meant to stand alone against an onrushing horde. That is why Rome reinforced these natural barriers with the most extensive network of fortifications in the ancient world, a network of such grand scope and huge cost that its like was not seen again until the age of Vauban, during the reign of Louis XIV—which, interestingly, saw huge fortifications emplaced in many of the same areas Rome chose to fortify. Within and behind them typically stood fifteen or more of Rome’s legions. It was the combination of natural barriers, reinforced with a massive defensive infrastructure manned by the stout legions of Rome, that created a military-centered frontier zone. Too many historians have broken these elements down to their constituent parts and analyzed them separately, leading them to claim, erroneously, that Rome did not have coherent strategic plans. But none of these parts was ever intended to stand or operate alone. Rather, they were designed from the start to be integrated, creating a synergistic effect that maintained the frontiers almost inviolate for the first two hundred years of the empire’s existence. It is one thing to have a band of barbarians crossing the Rhine by swimming or in hastily made boats; it is quite another to do so when there was a legion waiting to hack them to death as they came ashore.
Historians appear to understand these facts when they consider movement going in the other direction. In these cases, Roman advances beyond the established frontier zones are always fraught with such difficulties and perils as to make the idea of further conquests too costly to consider. One historian, trying to build this case, quotes an anonymous fourth- or fifth-century source—De rebus bellicis (On Military Affairs):
First of all, it must be recognized that frenzied native tribes, yelping everywhere around, hem the Roman empire in, and that treacherous barbarians, protected by natural defenses, menace every stretch of our frontiers. For these peoples to whom I refer are for the most part either hidden by forests or lifted beyond our reach by mountains or kept from us by the snows; some, nomadic, are protected by deserts and the blazing sun. There are those who, defended by marshes and rivers, cannot even be located easily, and yet they tear peace and quiet to shreds by their unforeseen attacks.43
Isaac considers this passage to be of great significance because it was written by a man of military experience and demonstrates that natural defenses, far from being a defensive barrier, acted as an obstacle that prevented the Romans from acting against their enemies. Why he and others suppose that such natural obstacles hinder the movements and actions only of the Romans and not of “native tribes” is difficult to understand.44
Major rivers also served other crucial purposes, which made them the natural foundation of any defensive network. For one, they greatly eased logistical and transport problems. The Rhine and Danube were huge highways that alleviated much of the burden of supplying the legions camped alongside them while also providing high-speed avenues of approach when Rome needed to move troops from one sector of the empire to another. Roman legions would have been drawn toward the great European rivers if for no other reason than ease of transport.
Before moving on, it is crucial that two other misapplications of strategic understanding be put to rest. First is the argument that Romans could not have considered the frontiers we have identified as true or permanent frontiers, because they so often sent large military forces beyond them. This imputes to the Romans a siege mentality akin to that of France in 1940, hiding behind its Maginot Line and hoping the Germans would stay on the other side. But this was not the Roman way. For at least the first few centuries of empire, a single imperative appears coded into Rome’s strategic DNA: seek out and obliterate troubling populations before they became a threat. The Romans never considered their fortress frontier zones as a final bulwark against the barbarians (Figure 1.3). Instead, the zones doubled as secure bases from which to gather forces and resources to go deep into enemy territory and strike Rome’s foes before they could assemble and organize in such numbers as to make a breakthrough into the heart of the empire a real possibility. Of course, as the threats on the other side of the frontiers changed and Rome’s capacity became increasingly feeble, Roman incursions became less frequent. Nonetheless, for most of the empire’s existence the frontiers were both defensive barriers and staging areas for offensives. Whittaker once called upon historians to give up on the myth that the Roman frontiers were an iron curtain through which nothing passed.45 In this regard he was correct; but he was thinking in terms of trade, not about how often Rome sent its armies beyond the frontier zones.
Figure 1.3 Reconstruction of a Roman fortress, Saalburg, Germany
The idea has also been put forward and generally accepted that Rome could not possibly have had an all-encompassing theory or, as Susan Mattern calls it, “a coherent empire-wide plan” because they employed dissimilar approaches in different frontier zones. This fragmentation of approaches based on different situations is held up as proof that Rome was incapable of thinking about grand strategy and hence simply defaulted to several local expedients.46 As modern strategists see it, however, historians have gotten it exactly backward: it would have been the height of strategic folly to employ the same approach throughout the empire when local circumstances dictated different solutions. So, rather than displaying a paucity of strategic thinking, the capacity to employ different strategic methodologies based on circumstances—ends, ways, and means—demonstrates a highly sophisticated strategic appreciation.
One further reason often presented for why the Romans lacked the capacity to think strategically and to create and execute long-term plans is the lack of a general staff or its ancient equivalent. In the modern era, such a staff is responsible for strategic plans and the coordination of major operations. Historians are willing to concede that Roman emperors and even governors employed a consilium to advise them on crucial matters of state and justice. According to Dio, the consilium’s membership could vary but usually consisted of the consuls, trusted advisers, and fifteen senators, the latter rotated out every six months.47 And while the power of the consilium varied from emperor to emperor, it gradually gained in power and influence as it took on the duties of administering the empire. So what likely started as an informal body of amici (friends) became increasingly formalized until by the reign of Constantine it was a separate department of the imperial government—the sacrum consistorium. Of course, the consilium was by no means a general staff or its ancient equivalent, but its existence demonstrates that there was a body of learned men to advise and assist the emperor. Also, it must be noted that until the Prussians created a planning staff in the nineteenth century, no ruler in history ever had such an entity. Does that mean that Alexander, Gustavus Adolphus, and Napoleon were incapable of strategic thinking? As Everett Wheeler asks, “Should we accept the view that the institution consuming, even on a conservative estimate, 40 to 50 percent of the state’s revenues and the most bureaucratized and best-documented aspect of Roman government lacked administrative oversight and planning?”48 In fact, the Romans maintained a huge military administrative apparatus throughout both the Republic and the empire. How could it have been otherwise? Without such an administrative and planning function, it would be impossible to arm, pay, and feed a far-flung army. Moreover, without some degree of strategic forethought Rome could not fight wars on multiple fronts, as it did many times in its history. As Wheeler points out, “Roman capability in maintaining its army, as well as an emperor’s ability to transfer units from one frontier to another and to assemble expeditionary forces for major wars, clearly indicates that general staff work was done, even if the specific mechanisms of higher command and control remain one of the arcana of Roman government.”49
There is clear evidence that the Romans kept excellent military records throughout the centuries of empire. Tacitus mentions one such document that was read to the Roman Senate soon after Augustus’s death in 14 CE:
This contained a description of the resources of the State, of the number of citizens and allies under arms, of the fleets, subject kingdoms, provinces, taxes, direct and indirect, necessary expenses and customary bounties. All these details Augustus had written with his own hand, and had added a counsel, that the empire should be confined to its present limits, either from fear or out of jealousy.50
That such records existed is clear from a later section of Tacitus quoted below. Considering that nearly a hundred years had passed before Tacitus wrote his account of the period, he must have had extensive records to consult as he outlined the dispositions of the empire’s military forces for the year 23 CE. It is also notable that Tacitus not only knew where the legions and fleets were but also was keenly aware of their purpose. It certainly appears that someone in 23 CE was thinking in strategic terms and laid out such notions so clearly that Tacitus could reiterate them almost a century later:
Italy on both seas was guarded by fleets, at Misenum and at Ravenna, and the contiguous coast of Gaul by ships of war captured in the victory of Actium, and sent by Augustus powerfully manned to the town of Forojulium. But chief strength was on the Rhine, as a defense alike against Germans and Gauls, and numbered eight legions. Spain, lately subjugated, was held by three. Mauretania was king Juba’s, who had received it as a gift from the Roman people. The rest of Africa was garrisoned by two legions, and Egypt by the same number. Next, beginning with Syria, all within the entire tract of country stretching as far as the Euphrates, was kept in restraint by four legions, and on this frontier were Iberian, Albanian, and other kings, to whom our greatness was a protection against any foreign power. Thrace was held by Rhoemetalces and the children of Cotys; the bank of the Danube by two legions in Pannonia, two in Moesia, and two also were stationed in Dalmatia, which, from the situation of the country, were in the rear of the other four, and should Italy suddenly require aid, not too distant to be summoned. But the capital was garrisoned by its own special soldiery, three city, nine praetorian cohorts, levied for the most part in Etruria and Umbria, or ancient Latium and the old Roman colonies. There were besides, in commanding positions in the provinces, allied fleets, cavalry and light infantry, of but little inferior strength. But any detailed account of them would be misleading, since they moved from place to place as circumstances required, and had their numbers increased and sometimes diminished.51
This passage also lays low another one of Isaac’s key claims: that if the Romans had any conception of modern strategic principles, “they kept quiet about it.” Tacitus presents clear evidence that Roman were specifically thinking in terms of mobile defense at the strategic level. As he states, the eight legions on the Rhine were given two crucial missions: to defend against the Germans and to handle any trouble that might arise in recently pacified Gaul, while the Dalmatian legions are tasked with supporting the four legions on the Danube and, if required, marching to the aid of Italy. As James Thorne has pointed out, “This is a strategy of mobile defense, if anything is.”52
David Potter believes that the Romans had lost little of the knowledge imparted by Aristotle centuries before. As Cicero claimed, for a senator to “know the state” he had to know the state of the army, the treasury, and the allies, friends, and tributaries of Rome, along with the attachment of each to Rome.53 It would be difficult to find a more succinct understanding of the underpinning of all strategic thinking: financial strength that paid for the military forces that were the foundation of Roman power. Cicero also warned, in an observation as true two thousand years later as it was then, that even a state possessed of overwhelming financial and military power could see its advantages thrown away by political imbecility.
Almost four hundred years after Cicero’s death the Notitia Dignitatum was compiled. This remarkable work, one of the few documents from the Roman chanceries to survive into the modern era, contains a complete accounting of the Western Roman Empire in the 420s and the Eastern Roman Empire in the 400s. It lists all court officials, vicars, and provincial governors, arranged by praetorian prefecture and diocese. Moreover, it lists by name all military commanders (magistri militum, comites rei militaris, and duces), along with their stations and the regiments under their control. In short, it is a complete record of the military formations of the empire, along with their locations.54 Between Cicero’s death and the completion of the Notitia Dignitatum we have numerous references to censuses and other strategic assessments that would only be made if they were meant to be consulted for strategic purposes. As Wheeler has noted, “If emperors kept detailed records on military strengths and location of troops, did they then fail to ponder their use?”55
Finally, let us turn back to David Cherry’s overview of Roman strategy, or the lack thereof, to a comment that demands some further analysis: “There is also little reason to believe that the Roman authorities considered it to be their duty to protect the provincial populations against those who lived beyond the frontiers.”56 This viewpoint encapsulates a view that fails to account for either the evidence or common sense. Although no surviving document unequivocally states that the highest purpose of Roman government is to protect the people, one can understand the priorities of Romans through their actions. If they did not care about protecting the civil populations—or, if one is ungenerous, protecting the tax revenues that a secure population provided the empire—there would be absolutely no reason to post thirty legions and a similar number of auxiliaries along the Roman frontiers. Rome undertook this tremendous military effort for the express purpose of securing the provinces and populations of the empire. One must ignore five hundred years of Roman military exertion to believe otherwise.
Coupling the idea that Rome did not truly care about the empire’s peoples with the notion that Rome had no conception of the empire’s geography negates both the need for a large military establishment as well as any hopes of deploying one in a useful manner. Following this logic means that Rome, for five hundred years, paid for a huge military force without ever being able to articulate a practical justification for its maintenance. Moreover, Rome somehow, by some act of supreme serendipity, managed to post this force along the frontiers, where they were most needed. If the Romans possessed no understanding of geography or capacity for strategic planning, could one assume they were just as likely to have their legions sunning themselves along the Mediterranean coast as to find them posted along desolate frontier zones? But if we accept that Rome’s placement of its legions in the absolute best positions to counter the known threats was not purely the result of a magnificent accident, then we must also accept that the Romans were capable of thinking in strategic terms, as well as of planning and executing strategic concepts.
Another idea that has gained currency recently is the notion that the barbarians on the other side of the Roman frontiers were not as dangerous as the ancients made them out to be. If this is true, then for fifty decades Rome wasted vast sums of money securing itself from enemies that rarely raised themselves above the nuisance level. But is it true? That is what we will discover next.