Spring AD 122 – Hadrian inspects the northern frontiers: part 4 Germania Inferior (#Hadrian1900)

In 122, perhaps in late spring, Hadrian returned from the Danube to the Rhine. The last stage of his journey along the German frontier before moving to Britannia would have taken him down the Rhine to Colonia Agrippinensis (modern Cologne), the Hadrianic capital of Germania Inferior. One of his most trusted friends, Platorius Nepos, who had governed the province since AD 119, probably accommodated the emperor and his entourage at his palace (praetorium).

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The region south of the Rhine was designated as the province of Germania Inferior around AD 85 under Domitian. It occupied part of modern-day Belgium, the southern Netherlands, and part of North Rhine-Westphalia in Germany. The principal settlements of the province were Colonia Ulpia Traiana (Xanten), Coriovallum (Heerlen), Lugdunum Batavorum (Katwijk), Forum Hadriani (Voorburg), Ulpia Noviomagus Batavorum (Nijmegen), Traiectum (Utrecht), Atuatuca Tungrorum (Tongeren), Bonna (Bonn), and Colonia Agrippinensis (Cologne), the capital of Germania Inferior.

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The province was dominated by the Rhine river (Rhenus), flowing northward and emptying into the North Sea. It acted as the province’s eastern and northern frontier, consisting of a continuous chain of military installations from Remagen in Rhineland-Palatinate down to Katwijk on the North Sea coast in the Netherlands. The legionary camps stood at Noviomagus (Nijmegen), Vetera (Xanten), Novaesium (Neuss) and Bonna (Bonn). Tens of thousands of troops were stationed in these camps. They secured the border and undertook important administrative tasks. They built roads, bridges and public buildings.

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The Rhine was one of the most important and fastest long-distance transport routes during the Roman period, connecting the Alpine region to the North Sea. It was also a line of communication and a conduit for culture. The sea route via the Atlantic and rivers flowing through Gaul, like the Moselle, the Rhône and the Saône, connected the Rhine and the province of Germania Inferior to the long-distance trade network. Both goods and people moved through the harbours of the military bases and civilian settlements.

The course of the Rhine today is not the same as in the Roman era, as it was straightened during the 19th century to aid shipping. In addition, its banks have been stabilised. In antiquity, its course described wide meander curves and included many secondary channels along its route to the North Sea. Roman harbours were built on the main channel, usually on the outer bank of meander curves. They were equipped with elaborate structures designed to protect the settlements from the dangers presented by the river current. Today, some former military forts are farther from the Rhine as the river bed has shifted repeatedly since the Roman period. In other locations, they have been washed away over time.

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The Rhine was not a fixed boundary or an insurmountable barrier, as the people of the Rhineland could cross from one bank to the other in many places. Ferries and travel by boat will have helped the connections between riverine communities, facilitating local commerce and trade. Transport vessels on the Rhine consisted mainly of flat-bottomed barges, characterised by a large load capacity and a shallow draft, enabling them to sail at low tide.

The local population worshipped the Rhine as a mighty river god. In a few surviving representations, the Rhine appears bearded with long hair and horns (its typical attribute), confirming the reports of ancient authors like Virgil (Aeneid 8.727), who described the Rhine as a horned deity called Rhenus bicornis (“two-horned Rhine”). The Rhine was also mentioned in terms of honour as “Father Rhine” (see here).

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The fleet of the Rhine, the classis Germanica, helped supply the army and made the river available as a commerce route (ILS 4757). It patrolled the Rhine and its navigable tributaries to control movement and deter river crossing by hostile bands. The classis Germanica was commanded by a praefectus classis from the equestrian order with a crew consisting of the officers (trierarchs), the rowers (remiges) and marines forming a centuria. The headquarters of the classis Germanica was originally located at Vetera and later at Colonia Agrippinensis (Cologne-Alteburg), three kilometres south of the military base), where it remained until at least the middle of the 3rd century. There were smaller naval units downstream at Novaesium and Noviomagus. 

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The army of Germania Inferior was typically shown on inscriptions as EXGERINF – EX(ercitus) GER(manicus) INF(erior). Apart from the physical obstacle of the river Rhine, the frontier system (limes) consisted of a military road on the south bank connecting around 30 forts interspersed with numerous watchtowers. This system successfully protected the Empire against German incursions and monitored the traffic passing through the Rhine corridor.

The first Roman military presence on the Lower Rhine dates back to c. 19 BC when a two-legion force was temporarily based at Nijmegen, soon followed by another major base at Neuss. A series of other military installations stood across central Germany, but after the disaster of the Teutoburger forest in AD 9, the Roman army redeployed on the left bank of the Rhine. By the end of the 1st century AD, the province of Germania Inferior had the largest concentration of military forces in the Roman world with four legions and some 30 auxiliary units, totalling c. 40,000 soldiers.

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After the institution of the province of Lower Germany, a few changes were made in the positions and sizes of forts, but most of the defences were gradually rebuilt in stone after AD 90. During Hadrian’s visit, the legions I Minervia and XXX Ulpia Victrix were stationed in Bonn and Vetera, while vexillations of the IX Hispana were supposedly at Noviomagus Batavorum (AE 1996, 01107). In addition to legionary bases, more than 30 auxiliary camps and 100 temporary camps existed on both sides of the Rhine. Auxiliary troops supported the legions on the limes while watchtowers placed at significant points along the Rhine would have monitored the traffic between the forts.

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The I Minervia was a legion raised by Domitian and named in honour of his favourite Olympian, the goddess Minerva. It was sent to the fortress at Bonna, where it remained until the end of the 4th century AD. During the reign of Trajan, the legion fought against the Dacians with the VI Victrix and X Gemina from Neuss and Nijmegen. In the war’s final years, I Minervia was commanded by Hadrian. With XXX Ulpia Victrix, I Minervia worked on numerous military and building activities in Germania Inferior.

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One of the most significant changes made by Hadrian in Germania Inferior was the dispatch of the VI Victrix from its base at Vetera to Britain and the arrival of the XXX Ulpia Victrix. The exact sequence of events is unclear, but the Sixth Legion may have arrived at its new base in Eboracum (York), presumably to take part in the building of the Wall, before Hadrian got to the province in July 122. As in Germania Superior, where frontier works started over a year before Hadrian inspected the limes in 121 (read here), the building of the Wall was probably ordered from Rome. Hadrian would have seen how things were progressing along the northern frontiers during his subsequent visit.

The XXX Ulpia Victrix (raised by Trajan around AD 105) had been commanded by Quintus Marcius Fronto, a close friend of Hadrian, who was in charge of reorganising the northern provinces. The Thirtieth Legion was to stay at Xanten for more than 200 years.

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The fortress of Vetera was one of the most important garrisons on the northern flank of the Roman Empire. There were two consecutive legionary camps at Vetera: Vetera I (dated 13/12 BC to AD 70) and Vetera II (dated 71 until at least the 3rd century). Vetera I was established as a base camp for the campaigns of Drusus and Tiberius at a strategic position opposite the confluence of the Lippe and the Rhine. The military camp accommodated two legions until its destruction during the Batavian Revolt in AD 70. After this, Vetera II was constructed at a nearby site, closer to the Rhine, for only one legion. It became the base camp of the VI Victrix and later the XXX Ulpia Victrix. The Thirteenth appears to have participated in new building activities at the fortress, as brick stamps suggest. The shifting course of the Rhine during the Middle Ages destroyed the camp and transformed the landscape into the Bislich Island of today.

A civilian settlement grew up north of the camp, inhabited by 10,000 to 15,000 army veterans and their families and other people of Germania and Gaul, eventually becoming a colonia (the highest Roman municipal rank) between early AD 98 and autumn 100 during the reign of Trajan. It became the second-largest urban centre of the province of Germania Inferior.

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Trajan transformed the former Germanic settlement on the Rhine into a Roman Colony (Colonia Ulpia Traiana) dominated by grand public buildings. It was a completely new town, surrounded by a wall that circumscribed an area of about 73 ha with six gates, 22 rectangular towers and ditches in front of the Wall. The Forum and the main temple lay at its centre. The public baths (finished around 125 during the reign of Hadrian) and the amphitheatre provided a high standard of living and entertainment. The Vetera legions and the Rhine fleet played a significant role in extracting and transporting the building materials for the public buildings. They also participated directly in the construction work (CIL XIII 8036).

Colonia Ulpia Traiana was accessible by boat via a branch of the Rhine. Its harbour was built immediately adjacent to the eastern town wall. Dendrochronological investigations of the wooden wharfage demonstrated that the harbour was first built in AD 46 and that various extensions and embellishment work took place in the last decade of the first century AD and during Hadrian’s reign around 130.

The city existed until the end of the 4th century and fell into decay after the conquest of the Rhineland by the Franks. The area of the Roman town was hardly built over after Roman times and remained undeveloped land until very recently when the area was opened up for industrial development. However, the ancient city was used as a source of stone for building the modern town of Xanten. Systematic excavations began in the late 19th century and have continued up to the present, while individual buildings in the former town were partially reconstructed as part of the Xanten Archaeological Park. About 10–15% of the urban area has been investigated archaeologically.

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The other fortress at Bonna (Castra Bonnensis) was constructed on the banks of the Rhine after the Battle of the Teutoburg Forest in AD 9, near the site of a previous auxiliary fort built by Drusus between 16 and 13 BC. Initially, the fortress was a timber-earth structure and was garrisoned by Legio I Germanica upon its transfer from Cologne. After its destruction during the Batavian revolt (69/70), the fortress was rebuilt in stone and became the base of the legion XXI Rapax. A few years later, after 83, the I Minervia was sent to Bonna, where it would remain for the following centuries.

The fortress had a square shape and covered an area of approximately 250,000 square metres, accommodating up to 10,000 troops. It remained in use by the army for over 300 years, almost the entire period of the Roman presence on the Rhine. It now lies beneath the modern city of Bonn in the Bonn-Castell precinct, but excavations have revealed the principia (headquarters building), the hospital, the warehouses and the barracks. The via principalis ran in a north-south direction parallel to the Rhine, the via praetoria and its extension, the via decumana, in an east-west direction.

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The military presence attracted civilians. Around two kilometres south of the fort, a vicus (Vicus Bonnensis) developed. Up to 10,000 people lived in the vicus during its heyday in the 2nd and 3rd centuries, including craftsmen, merchants and traders. They provided the soldiers with everything they needed. Areas of the vicus were excavated in 2006 near the present World Congress Center Bonn. The dig uncovered building foundations of workshops, strip houses, a Gallo-Roman temple and a public bathhouse. At around 80 hectares, the vicus at Bonna was one of the largest settlements in the Rhineland.

The vicus buildings were long and narrow, standing in rows along the street. One entered the half-timbered houses via colonnades porches (portici) which protected against the harsh climate. There was a public room on the street side, with stores, workshops or taverns. Living quarters were situated at the back. The occupants grew fruits and vegetables in the garden, kept small livestock, or practised their handcraft. Cellars, wells and latrines were also located at the back of the house.

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The legions of Germania Inferior were supplemented with many auxiliary units (infantry and cavalry) in which the natives could serve. The auxiliary fort of Burginatium, where a cavalry unit was stationed, supported the legions at Vetera in securing the border. Another cavalry unit was at Durnomagus, the home of a cavalry squadron from Noricum (the Ala I Noricorum) since the beginning of the 2nd century AD. It protected the limes between Colonia Agrippinensis and Novaesium. Another unit, the Cohors II Hispanorum, was stationed at Traiectum (Utrecht) and was involved in building activities around 125 and the construction of the local limes road.

The auxiliary fort of Praetorium Agrippinae also experienced building activities during Hadrian’s reign, ca. 124. The Roman road leading from this fort to the subsequent military settlement of Matilo has been identified and dated by dendrochronology to 123/124. A unit called Cohors II Civium Romanorum appears to have been involved in building the military road, as the inscription COH II CR found on one of the oak piles suggests (see here). The building activities and road works have been connected with Hadrian’s visit to the area.

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Colonia Claudia Ara Agrippinensium (Cologne) was probably the base of the end of Hadrian’s trip along the Lower Rhine frontier, residing in the praetorium, the governor’s palace and the headquarters of the provincial administration. At this time, the governor was Aulus Platorius Nepos, a close friend of Hadrian, who may well have accommodated him during his stay in the provincial capital. The two would go together to Britannia.

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With an urban area occupying approximately 96.8 hectares, Colonia Claudia Ara Agrippinensium was one of the largest towns northwest of the Roman Empire, with a total population of 45,000. Founded on the left bank of the Rhine by Agrippa as an oppidum of the Ubii (Oppidum Ubiorum), the city was made a colony at the instigation of the empress Agrippina in AD 50 and acquired a city wall. It became the political and economic centre, first of the Lower Germanic military zone and then, from AD 85, of the whole province of Germania Inferior. It was also the site of an altar (ara) for the Imperial Cult of Rome and Augustus, from which the town took its name.

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A camp for two legions, Legio I Germanica and Legio XX Valeria Victrix, existed nearby until the end of Tiberius’ reign when the legions were transferred to Neuss and Bonn. However, the Rhine fleet remained near Cologne-Alteburg. With Domitian’s founding of the new province, the commander of the legions of Germania Inferior became the provincial governor based in Colonia. Veterans from many parts of the Empire settled in the colony. The legions, however, were moved to Vetera, Noviomagus Batavorum, Novaesium (Neuss) and Bonna.

Large sections of the city wall are still standing. They surrounded the city since AD 50 when it became a colony. The Wall was about 2 metres thick and had a total length of roughly 4 kilometres. Nine town gates allowed entrance to the colonia; three in the east, two in the south, three in the west and one gate in the north. The main north, south, and west gates, through which the cardo and decumanus maximus left the town, were constructed as monumental, two- or three-storey gate complexes. At least three main roads converged to Colonia Agrippina. The cardo led to the road along the limes. The Via Belgica crossed the city from west to east (decumanus).

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In 98, Trajan, then governor of Germania Inferior and commander of the legions stationed on the Rhine, learned of Nerva’s death and accession to the throne during a stay in Colonia Agrippina. Hadrian, who was serving as military tribune at Mogontiacum with the Legio XXII Primigenia, brought the news to him.

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Hadrian raised the status of two communities in Germania Inferior: Forum Hadriani and Tongeren. Forum Hadriani (Hadrian’s Market), the chief town of the Canninefates tribe, received its name from Hadrian. From the evidence of one of the milestones discovered in 1997 in The Hague (AE 2000, 01022), we know that Hadrian raised its status to a municipium. The milestone, dated to the reign of the emperor Antoninus Pius, contains the abbreviation MAC which means M(unicipium) A(elium) C(ananefatium). Forum Hadriani was the northernmost Roman city on the European continent. It was located along the Fossa Corbulonis, a waterway connecting the Rhine and Meuse rivers. It was constructed around AD 50 by the Roman general Corbulo ‘to avoid the dangers of the sea’, as Tacitus states. Forum Hadriani is mentioned in the Tabula Peutingeriana (see here).

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The small market of Forum Hadriani had its own bathhouse, a temple complex and a paved main street. It hosted markets, had a port providing access to the Fossa Corbulonis waterway and boasted impressive embankments with timber quays and revetments over hundreds of metres. The wooden remains of the harbour of Forum Hadriani have been excavated, and dendrochronological datings of the wooden banks indicate that Hadrian improved the canal of Corbulo. Today, the majority of the archaeological remains of Forum Hadriani are located under Park Arentsburg, a national-listed heritage site in Voorburg.

It may also have been Hadrian (or Antoninus Pius) who conferred the rank of municipium on the capital of the civitas of the Tungri, Atuatuca Tungrorum (modern Tongeren, Belgium), which in imperial times seemed to have belonged to Germania Inferior. The evidence for a Hadrianic elevation to municipium is based on a discovery in 1990 at Tongres. An inscription on a Roman votive altar appears to be a dedication to Jupiter, the Genius of the Mun(icipium) Tung(rorum) (AE 1994, 1279). The monument dates from the 2nd half of the 2nd century or maybe from the beginning of the 3rd century.

The foundation of Atuatuca Tungrorum was directly connected to the Roman military presence, possibly serving as the recruiting centre of the auxiliary units, the alae and cohorts Tungrorum. The city was strategically situated in a fertile agricultural region with many rich villas whose products were destined for the Roman armies stationed along the Rhine frontier. Atuatuca Tungrorum quickly became a very important commercial centre, developing into a real Roman town with typical public and private buildings and streets, surrounded by a monumental city wall. It is believed that Hadrian had these impressive fortifications built around the town with a perimeter of 4544 m, ca. 500 m longer than the walls of Colonia Agrippina.

Atuatuca was also the region’s spiritual centre. Near the ramparts, a monumental temple complex was built on an artificial terrace, one of the largest in northwest Europe. This esplanade was 130 x 70 metres and surrounded by covered porticoes. The Gallo-Roman temple stood in the middle on a podium.

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Hadrian’s military achievements in the German provinces would be commemorated on coins minted late in his reign. An exercitus (army) issue known only in bronze sestertii featured a reverse portraying Hadrian on horseback addressing three soldiers with standards and the legend EXERCITVS GERMANICVS. Another coin of the ‘province’ type showed Germania standing as an armed figure in native dress, holding a large spear in one hand, the other supporting her characteristic hexagonal shield. 

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Having descended the Rhine to Lugdunum Batavorum, where the river flows into the sea, Hadrian would sail with his friend Nepos to Britannia. He would arrive in the summer of 122 and spend several months inspecting the Stanegate frontier and the progress of his new border installations, the stone wall that bears his name, the Vallum Aelium (in a scenario where work on the Wall started before Hadrian’s visit).

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Sources & references:

• Birley, Anthony R., (1997). Hadrian. The restless emperor, Routledge London New York pp. 113-122
• Fraser. Trudie E. (2006). Hadrian as Builder and Benefactor in the Western Provinces. BAR International Series 1484.
• Martin Kemkes. “Chapter 4/Archaeology of Germania Inferior.” The Oxford Handbook of the Archaeology of Roman Germany, edited by James, Simon & Krmnicek, Stefan. Oxford University Press, 2020.

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