ROMAN FRONTIER DEFENSE

Fort at Vindolanda, AD 105. The fort housed the First Tungrian cohort and a Batavian cohort.

WALL OF HADRIAN

By far the most famous defensive barrier in the Roman Empire; served for nearly 300 years as one of the major dividing lines between Roman Britain and the barbarians of Caledonia. With the exception of the Wall of Antonius, built just to the north, the Wall of Hadrian was unique in all of the imperial provinces. Emperor Hadrian ordered its construction in 122 A. D., and work was begun by Platorius Nepos, governor of Britain, who completed it around 126. The wall extended some 73 miles (80 Roman miles) from Wallsend (Segedunum) to Bowness-on-Solway (or the Solway Firth). It was intended not as a formidable bastion but as a base from which Rome’s presence could be maintained. Roman troops, mainly auxiliaries, manned its turrets and were to fight any large enemy force in the field while keeping watch on the frontier. In the event of a direct assault, the defenses were only adequate, perhaps explaining the collapse of Roman power in Britain from time to time.

The original plans were probably drawn by Hadrian. The barrier was to extend some 70 miles and be made mostly of stone, 10 feet thick, while the rest would be constructed of turf, 20 feet thick. The turf wall was completed, but the stone sections had only just begun when the plan was extended several miles to ensure that the barrier covered the area from sea to sea. Further, the stone portions were to be only 8 feet thick, instead of 10, and approximately 20 feet in height; the turf portions, 13 feet high. Forts were distanced some 5 miles from each other, with so-called mile-castles spread out every Roman mile, connected by watch-towers. Two ditches were dug. The one in front was approximately 30 feet wide and 15 feet deep, designed for defense and V-shaped. The ditch behind the wall has caused considerable archaeological debate. Called the Vallum (trench), it was straight and flat-bottomed, 20 feet wide, 10 feet deep and 10 feet across at the bottom, fortified on both sides by earthen walls (but then filled in). Scholars have speculated that it was once used for some other, non-military purpose.

Until the construction of the Antonine Wall in 142, Hadrian’s Wall was the only frontier marker in Britain. With the Antonine Wall in the north, its importance decreased briefly until 180, when the Antonine Wall was destroyed. In 196-197, Clodius Albinus took with him every available soldier in Britain for his bid for the throne, thus allowing the wall to be ruined, Septimius Severus repaired it from 205 to 207. Peace was maintained until the late 3rd century A. D., when the chaotic situation in Roman Britain following the deaths of the usurpers Carausius and Allectus brought the Picts down from Caledonia, Constantius I launched a restorative campaign but throughout the 4th century barbarian inroads put pressure upon the wall as Roman influence diminished. More invasions poured over the wall, only to be repulsed by Count Flavius Theodosius in 369. The last garrison on the wall withdrew around 400 as the barrier became a monument to Rome’s past.

ROMAN FORTS

A typical Roman fort of the Imperial period was shaped like a modern playing card, with two short sides and two long sides, and rounded corners. This is the evolved version of a Roman fort, since the earlier fortified camps of the early Empire were not so regularly shaped and were not generally designed as permanent bases for troops. The fort and supply depot at Rödgen in Germany was ovoid in shape, and while the fortress of Haltern was more regular in plan, it does not compare with the later permanent forts of the Empire.

Typically, early Roman forts were built of earth and turf ramparts (called murus caespiticus), topped by a timber breastwork, with access by timber gateways with towers on either side. There were usually interval towers ranged along the walls and at each corner. Forts were usually surrounded by one or more ditches, shaped like a letter V but with an aptly labelled “ankle-breaker” drainage channel at the bottom. The Romans usually took this drainage feature seriously, judging by the number of excavations that show that the ditch had been cleaned out and squared off. In the second century AD from the reign of Trajan onward, when the majority of forts had become permanent bases rather than semipermanent ones while the provinces were pacified and Romanized, forts and fortresses were generally, but not universally, built of stone. In some cases this meant refronting existing forts by cutting back the turf rampart, and in others building in stone from the outset.

Depending on the type of unit stationed in them, forts varied in size from 0.6 hectares for the small numerous forts in Germany and Dacia, to 20 hectares for a legion. There were a few double legionary fortresses such as Vetera (modern Xanten, Germany) and Mogontiacum (modern Mainz, Germany) until the failed revolt of Saturninus, who gathered the combined savings of his legionaries to attempt a coup against the Emperor Domitian. After this, Domitian decreed that no two legions were to be housed together.

The internal arrangements of fortresses and forts was on the whole standardized, but with regional or local variations. The center range usually housed the headquarters building (principia), flanked by the commander’s house (praetorium) and the granaries (horreae). There were four main streets within the fort, and the orientation of the fort was taken from the direction that headquarters faced. The road running across the fort in front of the headquarters was the via principalis, with its two gates labeled for the right and left sides (porta principalis dextra and porta principalis sinistra). The road that connected the principia to the front gate (porta praetoria) was the via praetoria, and behind the headquarters another road, the via decumana, ran to the rear gate (porta decumana).

In several forts archaeological evidence shows that there were other communal buildings, for example the workshop (fabrica) where metalworking, woodworking, and repair of equipment and weapons would take place. There was also a hospital (valetudinarium). It should be acknowledged that from the ground plans alone, the workshops and the hospitals might have been confused, each consisting of small rooms off a central courtyard, but in a few cases medical instruments have been found, which strongly supports the label “hospital.” The forts on Hadrian’s Wall at Wallsend and Housesteads, and the fortresses at Vetera (modern Xanten, Germany) and Novaesium (modern Neuss, Germany) are among examples where hospitals have been found. The majority of the buildings inside the fort would be the barrack blocks. For the infantry in legionary fortresses and auxiliary forts, barracks were normally laid out with ten rooms subdivided into two parts, one for sleeping and eating and one for storage, each room accommodating eight men, and therefore housing one complete century of eighty men. A verandah ran the full length of the ten rooms, and at the end of the barrack block there was usually a suite of rooms for the centurion. Cavalry barracks were different, reflecting the organization of the turma. From the evidence at the fort at Dormagen on the Rhine, and Wallsend on Hadrian’s Wall, it seems that the men and their horses were housed together. In at least three of the Dormagen stable blocks, there were double cubicles, with soakaway pits in those along one side, and hearths in those on the other, indicating that men and mounts shared the blocks (Müller, 1979; Dixon and Southern, 1992).

Roman Watchtowers

There is no real consensus as to what such monumental linear boundaries as the walls in northern Britain or between the Rhine and Danube in Germany were for and how they functioned. Almost as puzzling are cases where Roman soldiers were distributed in very small detachments, often less than ten men, manning watchtowers, constructed in lines following roads or along ridges. Such deployments seem to make little sense if the primary aim of the Roman army was to defend the provinces since any serious attack would surely have overwhelmed these weak defences.

Neither the view of the Roman Empire during the Principate as essentially defensive, nor the view that it was aggressive and still hoping to expand, explains properly what the army was actually doing. Mattern has recently suggested that the defensive-offensive distinction is anachronistic, and that we should view Roman foreign relations more in terms of concepts of honour and power. The theme of her book was essentially the ideology of empire, and it did not really explain how the army operated or whether or not its activities were effective. The shift in emphasis was very useful, for it is important to understand how the Romans conceived of their relations with other peoples, and it is within this framework that we should attempt to understand what their armed forces were actually doing.

For all the insights generated by this debate, the question remains of whether or not the Romans developed something which could reasonably be described as grand strategy. As with so many labels, there is a tendency for each contributor in the debate to provide his own definition for this term, making it easier to prove that the Romans either did or did not have one. The term was created in the twentieth century, and most of the definitions employed by modern strategic literature assume the existence of institutions and ideas utterly alien to the Roman Empire. For most modern states the ideal of international affairs is peaceful coexistence with their neighbours. Each state is considered to have a right to govern itself in its own way and by its own laws. In the modern world war is the anomaly, shattering the natural state of peace. For many societies in the ancient world the reverse was true, and peace was an interruption of the normal international hostility. The Romans were inclined to think of peace as the product of an enemy’s utter defeat, hence the verb `to pacify’ (pacare) was a euphemism for `to defeat’.

Peaceful coexistence with other nations, and most of all former enemies, was never a Roman aspiration. In some way we must relate our understanding of Roman ideology to the reality of military deployment in the frontier zones, many areas of which were constantly occupied for centuries on end. It is therefore worth considering the army’s deployment in these areas and trying to reconstruct what it was doing. In doing so we must try to look at the fringes of the Roman Empire from both directions.

Raiding does appear to have been endemic in the tribal societies of Spain, Britain, Gaul, Germany, Thrace, Illyria and Africa. Caesar claimed that the Helvetii migrated to occupy lands which would give them more opportunity to raid their neighbours (B Gall. 1.2).We are told that German tribes tried to keep a strip of depopulated land around their borders as a protection against enemy raids. This was also a measure of a tribe’s martial prowess and thus a deterrent to attacks. The Belgian tribes grew thick thorn hedges as boundary markers that were intended to delay raiding groups. They may also have been a sign that crossing them would be met with force, and it was probably no coincidence that Caesar’s army had to fight a battle at the Sambre soon after passing such a barrier (B Gall. 2.17, 6.23). The archaeological record of weapons burials in many regions of Europe confirms a picture of societies in which martial symbols were very important, and it is implausible to suggest that many Celtic tribes were not warlike warrior societies.

Our sources inevitably only report raids carried out on a large scale, usually by thousands of warriors. Only well-established leaders in reasonably united tribes could ever have mustered such forces. The warriors in many societies were strongly independent, choosing whether or not to join a leader who proclaimed that he was to lead a raid. Most raiding bands were probably much smaller. Even Ammianus, who provides far more detailed accounts of activities in the frontier provinces than any earlier source, never specifically mentions groups of fewer than 400 marauders. The distribution of Roman troops in penny packets to man lines of watchtowers might make a lot more sense if they were facing raids by equally small or smaller groups of warriors. The distinction between warfare and banditry blurs at this level, but there are many hints that small-scale violence was common in the empire.

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