The auxiliary troops of the Roman legions

The militarized band of land marking the imperial frontier in the Odenwald sector could clearly not withstand concentrated attacks and occasionally formidable bands of German marauders would penetrate the Limes; however, in general, it fulfilled its basic purpose and endured for a remarkably long period of time. From the density of watchtowers and supporting forts it is estimated that about fifty men guarded each kilometre of the frontier. Numerically, the German tribes outnumbered these frontier forces and physically, as individuals, were larger than Romans and more attuned to the climate. For a long time they were less effectively armed. Fortunately for the Romans, they rarely acted in combination. The Varian catastrophe showed clearly what could happen when they did.

Although we may tend to associate such a frontier with raids and invasions there were actually long periods of relative calm with the new settlers enjoying a pax Romana that benefited local tribes economically. It is thus generally accepted that, rather like Hadrian’s Wall in the north of Britain, the main function of a limes was to control the movement of people and trade goods into and out of the border provinces. It marked the limits of regions over which Roman administration held sway and its physical presence made an unequivocal political statement of Roman power to potential enemies. Ultimately however, in the third century AD, events in the Far East would generate hordes of migrating humanity that would push the German tribes into and through the Limes. Despite its advance location, far from the legion garrisons on the west banks of the Rhine, and the broken nature of the ground, the Limes would not be irrevocably breached by German tribes (known collectively as the Alemanni) until the dramatically-named Limesfall of AD 258-60. Thus, for a period of about four centuries, life in the three provinces of Germania inferior, Germania superior and Raetia was subject to Roman governance and influences. This heritage would profoundly affect the subsequent historical development of these regions. One should allow for the fact that the Roman empire was a long time dying: for instance, Köln, the last Gallo-Roman bastion on the Rhine did not succumb to the German tribe known as Franks until AD 458 .

At this point it is appropriate to look at the nature and disposition of the military forces which defended the great northern frontier. Fortunately our knowledge of the Roman army, in all its aspects, is remarkably detailed.15,16 During the second and third centuries AD, the Roman army of the Rhine comprised legions, auxiliaries and a fleet.

The legions were renowned for their coherency and flexibility. In practice, a legion could be a salaried killing-machine capable of slaughtering enemy prisoners and committing ruthless acts of genocide. The prime function of the six to eight Rhine-based legions was to move quickly to quell serious rebellions in the provinces or seal breaches of the frontier. Most of the time the frontier was at peace and skilled legionaries were often diverted to tasks of civil engineering, such as road-laying and bridge-building. The basic unit of a legion is commonly regarded as the century (80 men) and, judging by frequent naming on surviving memorials, it appears that the individual legionary identified primarily with his century and its commanding centurion, a man who had usually risen from the ranks. Six centuries formed a cohort and ten cohorts (I-X) made up a legion. (At one time it was the practice for Cohort I to consist of five double-centuries of veterans). Thus the nominal fighting strength of a legion, the armoured division of its day, was 5,000-6,000 men, accepting that this figure could be diminished by casualties, disease and desertions.

Hours in its passing, a legion on the march, five or six men deep, must have been a wondrous sight. As individuals, legionaries led a hard life and were subject to fearsome discipline with much time devoted to rigorous exercise and battle training.17 Training exercises included swimming and vaulting on to a horse. (Decimation, rarely applied, was an early Roman practice of punishing a defaulting cohort by selecting one tenth of their number by lot and killing them.) It appears that the preference was for legionaries to be stocky, agile and not necessarily tall. Mobility was vital. Carrying up to 35 kg of weapons, etc., a legionary could march 30-35 km a day. The unique character of the Roman legions is indicated by an observation that more than twelve hundred years would pass before European battlefields saw their like again. This shock event occurred when King Gustavus II Adolphus of Sweden led his disciplined Protestant army into the bloody arena of the Thirty Years War (1618-48).18

The legion long associated with the colonization and protection of the Agri Decumates was the legio VIII Augusta. From AD 70 its headquarters were at Argentoratum (Strasbourg), from whence it controlled traffic on the river Rhine. It is known that in AD 73 this historic legion built a road eastwards from Argentoratum to the Danube and the province of Raetia. This important link passed over the heights of the Black Forest and led to the establishment of the capital town (civitas) of Arae Flaviae (Rottweil) on the upper Neckar (Fig. 5). Legio VIII Augusta would later become extensively involved in the maintenance of the Limes: for example, in AD 185-92 its men built a substantial annex fort alongside the existing cohort fort at Osterburken. Detachments from its ranks were even sent to Britannia to assist in the establishment of Hadrian’s Wall (AD 122-130).

One can well imagine the uncertainty and superstitious fears of a legionary (Fig. 9), recruited from a warm Mediterranean land and bound for Germania, as he trudged north from Italy and saw the Alps for the first time. Leaving the military settlement of Augusta Praetoria (Aosta), snows permitting, he would trek over the ancient pass known today as the Col du Grand Saint Bernard. From this land of cold, wind, precipices and rock falls, he would descend to Claudii Vallensium (Martigny, southwestern Switzerland). This thriving trade centre was established by the Emperor Claudius, reputedly as a preparatory staging post for his AD 43 assault on distant Britannia. Passing through Aventicum (Avenches), our legionary would strike the Rhine at the city of Augusta Raurica (Augst, near Basel). Then he and his comrades would march toward and into the forbidding and seemingly endless forests of Germania. From hearsay, he would have been well aware of the pitiless nature and barbaric practices of his German adversaries.

Fig. 9 – Present-day legionary at Augusta Raurica ( Augst, Switzerland).

Auxiliaries (auxiliae) have a central place in the history of the Limes. Introduced in Augustan times as support for the legions, they functioned as either infantry units (cohortes) or elite units of cavalry (alae): the former often included specialists such as mounted infantry and archers. Typically an auxiliary unit could number 500, sometimes 1000 men, and was commanded by a centurion drawn from a legion. In due course, auxiliaries assumed the longterm task of manning the Limes. Auxiliary foot-soldiers were more lightly armed and diversely clad than legionaries, paid less and, in general, less rigorously trained. Carved memorials show them with a light oval shield, bearing either a spear or a long broadsword (spatha) rather than the shorter stabbing sword (gladius) of the legionary (Fig. 10). In the early days of the Limes, auxiliaries were non-Romans and were recruited either locally or from distant provinces of the Empire. As veterans with twenty-five years service, they could eventually qualify for citizenship. However, by the second century most recruits to the auxiliae were already Roman citizens; often they were the sons of veteran soldiers and recruited locally.

Fig. 10 – British auxiliary: re-enactment tableau at annex fort, Osterburken (April, 2009).

By this time the defence of Upper Germany, notably the Agri Decumates, had developed into a demanding military commitment. There were two legions on the Rhine (Mogontiacum, Argentoratum) numbering 11,000 men. They acted as backstops to the 17,000-19,000 auxiliaries who actually manned the Limes. Thus the muster for this section of the German frontier was at least 28,000 men.

Many present-day villages and towns along the line of the Limes owe their origins to small civil settlements (vici) that once housed veterans, the families of auxiliaries defending the Limes, artisans and tradespeople who supplied the general needs of fort garrisons. Being adjacent to a fort, the layout of buildings in vici was usually regular and ordered. Further afield, farm buildings were often grouped within stone-walled and gated enclosures: numerous sites of these villae rusticae have been found throughout the Odenwald. A rectangular area as large as two football pitches could include living quarters, bathhouse, stables, barns, paddocks and frequently a temple. Interestingly, in Germany today one notices that farms cluster within villages and are less likely to be isolated as in Britain. This feature seems to derive from ancient memories of a need for communal security.

Around AD 197, regulations were relaxed and soldiers were allowed to live with either their legal or ‘unofficial’ wives. As a consequence the vici adjacent to legion fortresses and forts along the Limes grew in size. Over the years auxiliaries on the frontier put down roots, tended to become static and resisted being posted elsewhere. This natural development threatened the intrinsic mobility of the Roman army. It was countered by the formation of special field-forces that could act as mobile reserves.

Life for auxiliaries serving on the Limes must have often been bleak and lonely, particularly when deep snows shrouded the silent forests for months on end. Their principal duties were to act as sentinels and to monitor the traffic that was channeled through carefully-sited gateways. The siting of the tall watchtowers was determined by the lay of the land and the requirements of signaling. Each tower provided accommodation for four to eight soldiers (Fig. 11). Access was by ladder. In the event of attack upon the line, semaphores, smoke columns or torches passed coded signals swiftly along the Limes and back to forts located a few hundred metres to the rear of the palisade. Reserve cavalry and infantry from these forts would then move quickly to the frontier and either drive the attackers off or, more satisfying to the military mind, envelop them in a dramatic pincer movement.

Fig. 11 – Cross-section of a typical watchtower. (© Römerkastell Saalburg)

On either side of the Limes, undergrowth and trees were cut down by these guardians of the frontier to provide a broad military zone many kilometres deep. It was common Roman practice for the ditch/palisade to be fronted by a staggered array of metre-deep pits. Each pit contained a sharpened stake or iron spike hidden beneath brushwood or vegetation. Ironically, these mantraps were known as lilia (lilies).

  1. Webster, Graham, The Roman Imperial Army of the first and second centuries AD (London: Adam & Charles Black, 1979) . []
  2. Yann Le Bohec, The Imperial Roman Army (London: B.T. Batsford, 1994). []
  3. G.R.Watson, The Roman Soldier (London: Thames and Hudson. 1969) 54. []
  4. Russell F. Weigley, The Age of Battles: the Quest for Decisive Warfare from Breitenfeld to Waterloo (Bloomington and Indianapolis: Indiana University Press, 1991) Chapter 1. []