Tacfarinas claimed that the withdrawal of these troops was a sign that the Roman Empire was collapsing and had already begun to pull out of Africa altogether. For all the locals knew, this might be true, and once again he resumed raiding and every success won him more followers. In Mauretania the old king had died and was succeeded by his young son, who was equally staunch in his alliance with Rome but a good deal less popular. Dislike of the new ruler readily fed hostility to the Romans and enthusiasm for raiding and plunder, giving Tacfarinas new allies. Another who joined him was the king of the Garamantes, who provided warriors and a market for saleable booty. The attacks on the Roman province grew larger, culminating in the blockade of the town of Thubuscum on the frontier with Mauretania. Publius Cornelius Dolabella, the new proconsul and another man with considerable military experience, rushed to its relief and broke the siege. Several chieftains of the Musulamii were executed on suspicion of planning to join the war against Rome. Copying his predecessor, Dolabella split his army into four main columns and numerous roving detachments, bolstering their numbers with allies supplied by the king of Mauretania, men who were used to tracking and fighting in the desert.
In AD 24, the eighth year since he had begun his fight with Rome, Tacfarinas was finally cornered. Dolabella received a report that the war leader was camped at a place called Auzea, in wooded country where he felt himself secure. A special column was put together, carrying only essential equipment and supplies, and force-marched to the place. The Numidians were surprised, caught with their horses tethered or grazing, and were unable to escape or organise a defence. The frustrations of years of chasing such an elusive foe fired the Roman soldiers, who were ordered to take or kill Tacfarinas above all else. His son was captured, his bodyguard cut down, and after a fierce fight the leader was also killed. The defeat and death of this charismatic man finally brought the war to an end, although since victory had already been declared and Blaesus generously honoured, Tiberius refused to grant triumphal ornaments to Dolabella.8
GARRISONS, FORTS AND WALLS
The war with Tacfarinas is usually described as a rebellion, since the lands of the Musulamii were already part of the Roman province when it broke out, and it conforms to the common pattern of at least one major revolt within a generation or so of conquest. There is no evidence for a rising on a similar scale in the same area in the centuries to come, much as lowland Britain was peaceful after Boudicca. In the future, the greatest concentration of Roman troops would be in Mauretania Tingitana, after the annexation of the allied kingdom by Caligula. Otherwise, a comparatively small number of units and bases held a much larger geographical area. If there was trouble requiring active operations by the Roman army, then it seems mostly to have been on a small scale. Yet the region was not totally denuded of troops, and not only were bases established, but substantial systems of ditches and ramparts constructed as barriers to the movement of animals as much as people. These helped to channel seasonal movement by the pastoralists who formed the bulk of the population, directing them to areas where they could be monitored and taxed. The focus of the military presence shifted, the frontier advancing, and it was clearly considered worthwhile to have military outposts dotted across a wide area.9
The Roman provinces in Africa bordered on land that the empire did not control, large parts of it desert or semi-desert with little or no settled population. This border was long and open, even when the frontier was moved forward, and this meant that conflicts like the revolt of Tacfarinas also had much in common with campaigns fought on the frontiers, drawing in peoples who lived outside the empire. Tacitus describes the war at greater length than many conflicts involving larger armies, using these passages almost as punctuation to his main narrative tracing the increasingly despotic rule of Tiberius. Even though he is often vague on important details, especially of geography, his account still gives us a fascinating picture of a long-running struggle between the Roman army and a determined indigenous people whose principal mode of warfare was the raid. It shows the Romans adapting to the local situation, experimenting with different strategies, sometimes during the same year, and mixing mobile columns with fixed fortifications to put pressure on their opponents.
Such flexibility and the speed with which the local situation could change need to be borne in mind when looking at the Roman army on the frontiers, where so much of the evidence for its deployment comes from archaeology. In many cases this allows us to plot on a map lines of forts, fortresses and smaller installations such as fortlets and towers, but it is incredibly rare for any of these sites to be mentioned in our sources. Inscriptions tell us something about the garrisons of some bases, and excavation provides detail of the development of the sites and glimpses of the lives of the soldiers and civilians who lived in and around them. They tell us far less about what the garrisons were doing and why they were stationed there. It is a sobering thought that Hadrian’s Wall is only mentioned some half-dozen times in Greek and Latin literature, even including Bede and others who wrote after the Roman period. The claim that it was built ‘to separate the Romans from the barbarians’ comes in a very late and often unreliable source, but is the only explicit statement about its purpose.10
Today Hadrian’s Wall is a World Heritage Site, famous as one of the greatest monuments left by the Romans. Yet not only does it scarcely feature in our literary sources, it was also a highly unusual project, very different from the bulk of the imperial frontiers. Although there were other linear barriers, in the main constructed of earth, turf and timber rather than stone, these were rare and covered only a small proportion of the frontiers. If possible the Romans far preferred to employ the natural barrier of a river, most obviously on the Rhine and Danube, as well as smaller rivers such as the Main, and to some extent the Euphrates. Rivers encourage communication, fostering trade and cultural exchange, so that the peoples living on either side often have much in common, and this had led to an unfortunately persistent myth that rivers do not make good frontiers. In fact they provide clear boundaries and significant obstacles to any movement on a large scale. With few exceptions most army bases were on the Roman bank, and it seems that bridges across the rivers were not part of the system. Trajan’s great bridge across the Danube was partly dismantled within decades of its construction even though it connected to the province of Dacia. There were no permanent bridges across the Rhine where it was the frontier after the early first century AD. Yet the rivers themselves were kept under close control, patrolled by flotillas of boats, and the army was fully capable of building a bridge when it needed one. One advantage of stationing garrisons close to a river was that bulky supplies such as grain could travel along it to keep them supplied.11
Yet there were not always suitable rivers in a convenient place, and so some frontiers lacked such a clear natural feature. In the later first and early second centuries AD, the Romans moved the frontier of Upper Germany and Raetia forward, creating a more direct link between the main lines of the Rhine and the Danube. It is improbable that this was simply due to the desire for a shorter frontage, and more likely connected with the need to control the peoples of the area and those living beyond them. In Britain the first organised frontier was in what is now southern Scotland, before this was abandoned and the army moved back to the line of the Stanegate road. Hadrian’s Wall was constructed close to this, but almost as soon as it was finished it was decommissioned when a fresh advance was made and the Antonine Wall built on the line between the estuaries of the Rivers Forth and Clyde. This in turn was abandoned and Hadrian’s Wall reoccupied, remaining in use until the end of Roman Britain over 200 years later. Apart from a few vague or ambiguous comments, none of our sources explain why these changes occurred, leaving us to look at the installations themselves and try to deduce their purpose.12
While emperors allocated resources to each area, and gave orders for any significant advance or withdrawal, the detailed implementation of these instructions was left to provincial governors,
who then reported what they had done. Much had to be decided by the man on the spot, for this was a world almost wholly without maps as we would understand them. There were some drawn to scale and close to the modern ideal, such as the famous plan of the City of Rome, but these covered only a few areas. Ptolemy of Alexandria was one of several geographers to produce the data for a world map superimposed with a grid to show the true relationship between the continents, and was on the whole fairly accurate. His work was large-scale and it is hard to know how often such maps were actually made. More common were plans based on written itineraries, which focused on routes, indicating the main roads, the cities and towns on them and distances between them. There was no attempt to show the correct relationship between places and so the countryside in the gaps between towns and cities is shrunk or expanded for convenience. The best surviving example, the Peutinger Table, is compressed to fit the entire empire on one long scroll. Such plans were functional, for they did show the way to get from one place to another, and gave an indication of the distances of each stretch of the journey. They were not intended to guide off-road travel and were useless for this, but then no state official, officer in charge of any significant body of troops, or even an ordinary traveller would choose to avoid going by road on any long journey. They also failed to give reliable indication of the positions of provinces and other territories relative to one another.
The absence of detailed maps is seen by some historians as proof that there was little central strategic planning in the Roman Empire. This is part of a wider trend in scholarship to emphasise the primitiveness of the Romans, a reaction against some older studies – and the deeply entrenched popular view – that stressed the modernity of ancient Rome, seeing Romans in essence as ‘just like us’. It is healthy to challenge existing wisdom, and often this is revealing. Studies of the frontiers that look at a modern map, declare lines based on natural features as the ‘best’ positions and then judge the Romans on how well they conformed to this are rightly dismissed. The Augustan attempt to create a province in Germany reaching to the Elbe was not the result of studying a map and seeing this as a shorter frontier line connecting to the Danube frontier than one based on the Rhine. We simply do not know how much sense Augustus and his advisers had of the geography of the region, especially before Roman armies reached it. Political geography – the divisions into peoples and the followers of particular leaders – was also far more important in Roman thinking than physical geography. It was peoples, rather than the land itself, that submitted to Rome, and it was peoples, whether allies or provincials, who needed to be controlled and defended. Information about them can be as readily expressed in words as in the diagrammatic form of a map or plan.13
Yet too much stress on the primitiveness of the Romans is unconvincing. Modern maps are very modern indeed – the Ordnance Survey in the United Kingdom began its major work when Britain was threatened with invasion by Revolutionary and Napoleonic France, and much of the country was not covered until later in the nineteenth century. Other parts of Europe, let alone the wider world, were not accurately mapped until well into the twentieth century. It is a mistake to take all this for granted, just as it would be to wonder how anyone in the past navigated or made strategic decisions before the advent of GPS and satellite imaging. At a generous estimate, it is only in the last two centuries that statesmen and military leaders have had access to significantly more information about the wider world than was available to Roman emperors. Napoleon and Wellington often had to make do with poor and unreliable maps, so sent officers out to produce more accurate ones, even though this was inevitably a slow process. Armies on campaign need very detailed topographic information, and even now will supplement modern maps with direct observation.
Even if they had possessed the levels of information provided by modern maps, it would have made no sense for emperors to direct the small detail of the army’s dispositions and operations on the frontiers, given the slow pace of communications. Provincial governors had a better chance of understanding the local situation, in particular in areas where the military presence was long established. There is clear evidence from several systems of towers built by the army on the frontiers that their positions were carefully surveyed and chosen, with each one placed so that it could be seen by a larger base, permitting signals to pass between them. The tower’s field of observation was important, but secondary to this. On the rare occasions when a tower was built on a key point invisible to any larger garrison, a second tower was sited to act as relay station between the two. The Roman army’s skill in understanding and working with topography is shown very well in the erection of these lines of towers, something that could only be done by people on the ground. Even the best map is unlikely to show areas prone to flooding or where line of sight is blocked by trees or other vegetation.14
Tacitus praised his father-in-law Agricola for his skill in choosing the sites of forts and providing them with well-stocked granaries, so that none of those he established were lost to enemy attack. The compliment was a conventional one, which in itself is an indication of how important an understanding of the ground was for Roman commanders. Defence was one consideration. The fort needed to offer security to its garrison and also allow them to perform the wider function requiring the troops to be there. Although a position on high ground offered advantages, it did not matter if the site chosen was not on the highest elevation. Until the development of effective cannon, being overlooked by hills outside of bowshot was not a significant disadvantage – something too often forgotten by archaeologists, whether discussing Roman military bases or Iron Age hillforts.15
Most forts appear designed to accommodate an entire unit, although there are exceptions, where the garrison appears to have consisted of detachments. Some caution is needed. Excavation is time-consuming and costly, and even an auxiliary fort presents a very large site, while legionary fortresses are more than ten times bigger. No legionary base has ever been fully excavated, and only a few forts have been substantially or wholly explored. The Roman army built these bases to a fairly standard pattern, so that many excavation plans represent guesswork, optimistically linking the finds from small sample trenches to form the expected layout of buildings. Understanding the location of forts and other military bases is difficult, since we tend to know very little about the local circumstances. The latter might well have changed over time but, unless such changes prevented the garrison from performing its most important roles, the fort could remain in the same place. The fort at Arbeia (modern South Shields on the Tyne) has been fully excavated and has revealed substantial changes in its design and, presumably, function. At one stage much of the fort was given over to twenty-two granaries, suggesting that it acted as a supply depot for a wide area.16
For all the Romans’ skill at engineering and understanding of the landscape, there were doubtless plenty of cases where sites were poorly chosen, and sometimes excavation reveals drastic modification. The design of Hadrian’s Wall was altered several times. Before it was completed the curtain wall was reduced in width from 10 feet to 5 and a half feet – small sections joined on to milecastles and some foundations had already been laid down to the original plan and can still be seen today. Also early on, the decision was made to place some forts actually on the line of the wall itself, and at Houseteads this meant building on top of a turret. Later, the northern gates of most milecastles were walled up, leaving just a narrow door allowing access to the front of the wall. Ideas changed, bases and fortifications were adapted. Recent excavation of the earliest frontier system in Scotland, and in particular the turrets and outposts on the Gask ridge, suggest that it was occupied for far longer than we assumed, perhaps for almost two decades, and in that time there are signs of rebuilding. The vast majority of Roman army bases have seen limited field work, especially employing modern techniques, and simply plotting them on a map and guessing at their function is unlikely to tell us anything useful.17
It is also wrong
to think of the garrisons of auxiliary forts, let alone the much larger legionary fortresses, as spending the bulk of their time in residence, peering over the rampart at a hostile environment while nervously awaiting an enemy onslaught. Only in a few areas and for limited periods of time was this ever the case. When the army fought, it tended to do so in the open, confident in its superiority over the enemy – misplaced confidence in the case of Decrius, but usually valid. When campaigns occurred, much or all of the garrison joined other army units to operate in the field. When there was less prospect of major operations, then soldiers were drawn off to patrol, provide escorts, to build and to administrate elsewhere. One of the Vindolanda writing-tablets gives the current strength of cohors I Tungrorum, the double-sized or milliary auxiliary cohort which garrisoned the fort from around AD 92–97 and had a nominal strength of just over 800. On 18th May (year unknown) the unit mustered 752 of all ranks, including 6 centurions, but no fewer than 5 centurions and 456 soldiers were currently away from the garrison. The largest detachment consisting of 337 men and (probably) 2 centurions, were not too far away at Coria (modern Corbridge). The remainder were in smaller groups, some in London, another 46 men serving in the bodyguard of the provincial legate, so perhaps also in London or escorting the governor elsewhere in the province. Of those at Vindolanda, 31 were in the garrison’s hospital and unfit for duty, leaving 265 and a centurion available.18
Other surviving strength returns show a similar picture of widely scattered units. On 31st December early in the second century AD, the mixed cohort, cohors I Hispanorum Veterana quingenaria stationed on the Danube had 546 soldiers on its books, ‘ . . . including 6 centurions, 4 decurions; 119 cavalry; also including __ duplicarii, 3 sesquiplicarii, 1 infantry duplicarius, __ infantry sesquiplicarii’, and gained another fifty, including returning stragglers, in the first weeks of the new year. Permanent reductions in strength were then recorded, such as men transferred to other units, and fatalities, with a soldier killed by bandits and one or more drowned. Others remained on the strength, but were currently detached, for instance collecting grain and clothing from Gaul, or sent to get horses, and still more attached to other posts, or serving various officials. One party were ‘across the Danube on an expedition’, others attached to a force of scouts led by a centurion, and separate detachments guarding grain ships, the grain supply, and draft animals, or fetching cattle from the Haemus Mountains. Unlike the cohort at Vindolanda, most of the centurions were with the main unit, although three out of four decurions – the commanders of the four turmae or troops of horsemen – were absent.19
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