Winter AD 121/2 – Hadrian inspects the northern frontiers: part 1 Germania Superior (#Hadrian1900)

In the year AD 121, Hadrian left Rome and set off on an ambitious tour of the western provinces. His first intended destination was the German frontier (limes) which he probably reached in the autumn or winter of that year. A passage in Dio Cassius describing Hadrian bareheaded in the “German snows” (Dio 69.9.4) plausibly refers to his wintering with the troops at the garrisons in Germany in 121/2. From there, Hadrian was to implement his new military policy of defensive imperialism.

Voyage of Hadrian 121-123.
Map created by Simeon Netchev for Following Hadrian (CC BY-NC-SA 4.0). Click to enlarge.

Having travelled by ship to Massilia and then up the Rhône (see here), Hadrian’s route towards the German frontier will certainly have been along the Via Agrippa, the main Roman road from the Mediterranean to the Rhine. From Lugdunum (Lyon), Hadrian would have gone north, passing through Cabillonum (Chalon-sur-Sâone), Andematunnum (Langres), Divodurum (Metz) and Augusta Treverorum (Trier).

Map created by Simeon Netchev for World History Encyclopedia and Following Hadrian (CC BY-NC-SA 4.0). Click to enlarge.

A series of milestones dated 120 and 121 were set up in Gaul and Germany along these roads, possibly anticipating the imperial visit. One milestone (CIL XVII 537), albeit incomplete, comes from Scarponna (Dieulouard), a way station along the road that connected Andematunnum (Langres, France) to Augusta Treverorum. Another one was found north of Dalheim (Ricciacum) in Luxembourg along the road that linked Divodorum (Metz) to Augusta Treverorum (CIL XVII 543). The last one comes from Bingen in Germany, which connected Augusta Treverorum to Mogontiacum (AE 1979, 417).

The roads on which Hadrian marched are depicted on the Peutinger map. In circles are the find spots of the Hadrianic milestones. Click to enlarge.

The Roman territory in Germania was then divided into two imperial provinces, Germania Superior on the Upper Rhine (Upper Germany) and Germania Inferior on the Lower Rhine (Lower Germany), which were governed by consular legates. Mogontiacum was the capital and governor’s residence of Upper Germany. It was also the fortress of the legion XXII Primigenia in which Hadrian had served as military tribune 24 years earlier (IG II² 3286). The other legion protecting the province was the VIII Augusta, garrisoned at Argentoratum (Strasbourg). These legionary fortresses were the largest military installations, covering on average 20 hectares (50 acres) and holding a legion of about 5,000 men. Both legions played a key role in the different stages of development of the limes, as shown by the inscriptions and tile stamps recovered from forts and baths.

Civilian towns in the hinterland of Upper Germany had developed on both banks of the Rhine. These urban centres were organised as civitates, regional market towns with a forum and a basilica capable of performing various social, administrative, economic, and religious functions. They appear to have been created to replace former military vici after the troops had moved on along the frontier line. Some of these agglomerations raised to civitas capitals, semi-autonomous communities acting as the administrative centre for the surrounding tribal areas.

Left of the Rhine, these main towns included Noviomagus (Speyer), Borbetomagus (Worms) and Brocomagus (Brumath). On the right bank of the Rhine, Nida (Frankfurt-Heddernheim), Aquae Mattiacae (Wiesbaden) and Lopodunum (Ladenburg) Baden-Baden, and Rottweil developed into capitals, probably in Trajanic times. The civitas capitals were distributed homogeneously throughout the northern part of Upper Germany. Augusta Raurica (Augst) and Aventicum (Avenches) were the two high-ranking coloniae, while Arae Flaviae (Rottweil) was the only municipium.

A chain of permanent cohort forts and watchtowers protected the limes demarcation line to the east of the Rhine. Begun under Trajan (Kortüm, 1998), these frontier arrangements continued to evolve under Hadrian and the successive emperors until the abandonment of the limes around AD 260 during the reign of Gallienus.

The forts that housed the auxiliary troops were much smaller than the legionary fortresses, ranging between 1.2 and 4 hectares (3 and 10 acres). They were organised into three basic types; the infantry cohort (cohors peditata), the cavalry squadron (ala), and the infantry with an attached cavalry contingent (cohors equitata). The fourth type of unit, the so-called numerus, was a specific military corps on the limes occupying a small fort (fortlet) with an area of 0.6-0.8 hectares and generally accommodated between 120 and 160 troops. According to Paul Holder’s survey, there were about one ala and fifteen cohorts in Germania Superior during Hadrian’s rule.

The limes in Germania Superior. The Trajanic/Hadrianic forts appear in dark blue. Author: ziegelbrenner CC BY-SA 3.0, via Wikimedia Commons

With its important tributaries such as the Neckar, Main, Moselle and Ill, the Rhine (Latin: Rhenus) became a great artery of communication and played a vital role in supplying the army in the two Germanies. It also benefited the civilian cabanae and became the basis of the economic development of the civitates. Along its banks stood the two legionary bases of Germania Superior, hubs of military planning and important road junctions. One of the tasks of the legion VIII Augusta at Argentoratum was the control and the navigation on the river. There, the Rhine was referred to as Rhenus Pater (“Father Rhine”) by Oppius Severus, commander of the VIII Augusta under Hadrian between AD 122 and 134 (see here). The Classis Germanica, the Roman fleet assembled in 13 BC in Germania Superior and Germania Inferior, was responsible for monitoring the entire Rhine and its navigable tributaries. 

The confluence of the Rhine and the Main near Mainz.

Having served for many years on the empire’s frontiers and participated in Trajan’s wars of expansion, Hadrian, the emperor, chose to conserve rather than expand. He withdrew from the furthest conquests and decided to formalise and improve the existing frontier system. Hadrian’s motive in Germany was to maintain the Upper German–Raetian limes, marking the frontier between the Rhine and the Danube. A celebrated passage in the Historia Augusta credits Hadrian with installing a linear barrier. The text claims that “in many regions where the barbarians are held back not by rivers but by artificial barriers, Hadrian shut them off by means of high stakes planted deep in the ground and fastened together in the manner of a palisade.” (HA Hadr. 12.6). No province is mentioned by name, but the HA passage appears in the context of Hadrian’s visit to the northern provinces and matches the recent archaeological findings in Germany.

During excavations in 2002/3 at Marköbel in the Wetterau, the fertile plain north-east of Mogontiacum, well-preserved timbers were uncovered inside two waterlogged stretches. Tree-ring analyses showed that the trees were felled in the winter of 119/120 (Schallmayer, 2003), implying that the palisade was already under construction when Hadrian arrived in the province. He might have checked on the progress of the frontier and liked what he saw as he ordered the legions to construct a continuous fence along the Taunus, Wetterau and Odenwald limites (read more here).

Remains of the palisade limes were unearthed at Marköbel in 2002. The palisade was made of split tree trunks up to 50 cm in diameter and strengthened by crossbeams.
A stretch of the Hadrianic palisade was reconstructed at Markobel in 2003.

Hadrian’s precise whereabouts within the German provinces are uncertain. He probably first placed his headquarters at Mogontiacum, a town Hadrian knew from his days as a legionary tribune with XXII Primigenia twenty-two years earlier in AD 97/8. Mogontiacum was the residence of the governor of Germania Superior. An inscription from Aquilea (AE 1934, 00231) testifies that Gaius Publicius Marcellus (consul in 120) governed the province at the time of Hadrian’s visit. A graffito on a ceramic shard (AE 1964, 00148) found in Mainz relates to the praetorium of the winter camp of XXII Primigenia established during Marcellus’ governorship. His residence may have accommodated the emperor and his officials during his stay in Mogontiacum.

]SS / denuntiavi T(ito) Elvissio Secundo / uti adsit Mogontiaci ante pr(a)etorium / Poblici Marcelli ad hiberna leg(ionis) XXII P(rimigeniae) P(iae) F(idelis)

Mogontiacum was founded as a legionary camp around 13/12 BC by military commander Drusus on the western banks of the Rhine and opposite the mouth of the Main. In the 1st century AD, the strategically favourable location on the Rhine turned Mogontiacum into an ideal military base for Rome’s offensive against Germania. After the end of the military campaigns, the town remained a significant garrison as the military administrative centre for the limes. It became the provincial capital of the Roman province of Germania Superior towards the end of the 1st century AD and developed into a civilian administrative and economic centre. Mogontiacum was named after Mogon, the Celtic equivalent of Apollo, who was also worshipped in Britain by Roman soldiers from the Germanic tribe of the Vangiones (RIB 1225, RIB 971).

Plan of Mogontiacum. Author: Bruce (Wikimedia)

The legionary camp was first constructed as a wooden and earth structure and was rebuilt in stone around AD 70. It could accommodate two Roman legions (around 12,000 men), and a total of nine different legions were stationed there in the course of the 1st century AD. From the year 93, Legio XXII Primigenia became the only legion to occupy the camp until the middle of the 4th century. Numerous tile stamps and stamped ceramics from Mogontiacum testify to the legion’s presence there, while some of its veterans are known by name through inscriptions on tombstones. Mogontiacum was also an important base for the Roman fleet on the Rhine.

Theodor Heuss Bridge over the Rhine River as seen from Kastel towards Mainz. The Roman bridge of Mogontiacum existed here at least until the Germanic tribes crossed the Rhine in the early 5th century AD.
Building inscription of Legio XXII Primigenia (AE 1940, 00118).
Landesmuseum, Mainz.

The rapid growth of the canabae, the civilian vicus between the military camp and the Rhine, soon resulted in the construction of Roman public buildings, such as thermal baths and a theatre (once the largest Roman theatre north of the Alps) and administrative buildings. Most interestinglyMogontiacum possessed a relatively rare sanctuary dedicated to the Egyptian mother goddess Isis and her Phrygian counterpart Magna Mater (Cybele). It was established under the Flavian dynasty, which claimed to be protected by Isis following Vespasian’s acclamation at Alexandria in Egypt. Military brick stamps and imperial dedications found at the excavation site suggest that the army erected the sanctuary and was closely associated with the imperial cult. The cult centre in Mainz is the only excavated structure of its kind in Germany, but the combination of Magna Mater and Isis is also attested in Aachen.

The Roman theatre at Mogontiacum was once the largest Roman theatre north of the Alps, with a diameter of 116 metres, a stage width of 42 metres, and a capacity of roughly ten thousand people.
The Sanctuary of Isis and Magna Mater was discovered in 1999 during the construction work of a shopping gallery in the city centre of Mainz. No actual temple structure was uncovered, but rather a sacral district with an encirclement wall and various structures.

From Mogontiacum, Hadrian would have been able to proceed along the frontier line to inspect the military forces and installations, determined to see everything for himself and make assessments on the spot. “He personally viewed and investigated absolutely everything.” writes Cassius Dio, “not merely the usual installations of the camps, such as weapons, engines, trenches, ramparts and palisades, but also the private affairs of everyone, both of the men serving in the ranks and of the officers themselves—their lives, their quarters and their habits” (Dio, 69.9). The HA adds that Hadrian insisted on reinvigorating discipline among the soldiers and kept them on continual exercise as if war was imminent. He lived with the troops, shared their basic military diet, and ate, like them, in the open (HA Hadr. 10.2-3).

Another passage in Cassius Dio’s book 69 has Hadrian “inspecting all the garrisons and forts”, removing some, relocating others and establishing new ones. While there is no certain proof that Hadrian ordered the troops to build new forts, two extra fortlets (Neuwirtshaus & Haselheck) appear to have been added around AD 120 on the eastern Wetterau Limes stretch. Haselheck was constructed forward of the fort at Echzell and directly on the limes, while Neuwirtshaus protected a frontier section between two forts in a marshy area.

Fortlets in Germany were comparable to the milecastles on Hadrian’s Wall in Britain. They housed small groups of soldiers on detachment duty charged with the task of patrolling the frontier lines and securing border crossings. At Butzbach, the Degerfeld fortlet was added to the forward line to guard a major crossing-point where a road from Mogontiacum came northwards via Friedberg. The wood and earth fortlet was rebuilt and provided with a stone curtain wall, presumably during Hadrian’s reign (Schönberger, 1969).

Information board at the site of Kleinkastell Haselheck (photo taken in 2021).

As far as the auxiliary forts are concerned, two important earth and timber garrisons were rebuilt in stone at the beginning of Hadrian’s reign c. 120, perhaps anticipating the imperial visit. One was Grinario, the most southerly limes fort identified on the ground is Köngen, and the other was the ala camp Cannstatt (Stuttgart). Both forts belonged to a chain of six military installations along the Neckar that protected the major road from Mogontiacum to Augusta Vindelicorum (Augsburg). 

At least eight other auxiliary forts were expanded, improved or rebuilt in stone during the late Hadrianic period with the help of the XXII Primigenia. Brick stamps show that detachments from this legion were involved in several Hadrianic stone buildings in the Wetterau. Hundreds of stamped bricks were discovered in Saalburg fort, which was enlarged towards the end of Hadrian’s reign to take a cohort, II Raetorum (CIL XIII 7462). Other garrisons in the Wetterau were either partially or entirely rebuilt in stone by Hadrian’s troops, including Kapersburg, Echzell and perhaps Stockstadt. Further south on the Odenwald-Neckar frontier, the forts of Hesselbach and Böckingen were provided with a stone curtain wall. There is some uncertainty whether the forts at Arzbach, Ems and Rückingen and the forlet at Inheiden were late Trajanic or early Hadrianic.

The reconstructed Porta Praetoria, the main gate of the Saalburg Roman Fort. The gate takes its name from the Via Praetoria, the camp’s road running in a north-south direction.
Kastell Kapersburg is one of the best preserved limes forts. The fort was enlarged around AD 130, and its original timber defences were re-built in stone. The garrison was made up of 150–200 men.

Civic development in the province continued throughout Hadrian’s reign. South of the Main, a new civitas was founded for the Auderienses with Dieburg as its capital, while civitas Vangionum (Worms) was probably converted into a municipium under Hadrian (AE 1978, 534).

Milestone from Mainz-Kastel

Roads in Germania Superior were repaired at the time of Hadrian’s visit. In addition to the three milestones mentioned earlier, more evidence of Hadrianic road works exists. One milestone was erected in AD 122 on the restored road that linked Castellum Mattiacorum (a military camp in Mainz-Kastel) to Aquae Mattiacorum (CIL XIII 9124). Another milestone (CIL XIII 9084) found at Grinario in front of the fort is dated to AD 129. It was erected along the road leading south to Sumelocenna (Rottenburg). Its inscription indicates the distance to the neighbouring fort at Sumelocenna: 29 Roman miles (= 42.9 km). Thanks to this discovery, the Roman settlement of Grinario on the Tabula Peutingeriana (Peutinger Map) was identified as the fort and vicus of Köngen.


The existing frontier works in Germany consisted of a patrol path and timber towers linking a line of forts. The first phase of its development is dated to Trajan’s rule c. AD 100 (Kortum, 1999) with a series of new forts established on the edge of the Wetterau region and further south along the Main river, in the Odenwald and along the Neckar river. This kind of open boundary was no real obstacle for raiders and allowed uncontrolled traffic of commercial goods. Around AD 119/20 Hadrian took the step of adding a continuous timber palisade.

An artist’s impression of the ditch that replaced the timber palisade and the stone watchtower that replaced the wooden watchtower. Illustration: Heike Wolf von Goddenthow

The palisade consisted of trunks of oak trees, split in half and set side by side in a foundation trench 1 to 1.5 metres deep. It stood up to 3 metres above the ground. Up to 50 cm in diameter, the logs were pointed at the top and secured on the inside by horizontal cross beams. According to the diameter of the surviving trunks, the timber was taken from oak trees about 100 years old. In Upper Germany, the Hadrianic palisade ran continuously for 81 kilometres, highlighting the environmental cost of this new frontier. Some 700 trees were needed to build a single kilometre of limes palisade.

An artist’s impression of a wooden palisade and tower on the German frontier. Illustration: Heike Wolf von Goddenthow

Behind the palisade stood watchtowers, used for observing anyone approaching the frontier and sending messages to soldiers in the nearby forts. Forts along the frontier were 10 to 30 km apart, so there was no inter-visibility between forts. The towers, however, stood about 700 m apart so that communication between towers was possible. Those of the earlier Roman Empire were mainly constructed of timber and were later replaced by stone constructions. Roughly 900 watchtowers were constructed along the 550-kilometre-long Upper Germanic-Rhaetian Limes. The wood and stone towers were mainly square in plan and had sides measuring between 3 and 6 metres, suggesting a height of 7 to 10 metres.

A reconstructed timber tower on a dry-stone base (Wp 10/15) on the Odenwald limes.

Maintaining the highest military discipline and efficiency standards was a key preoccupation for Hadrian as he toured military units. He kept the soldiers on frequent exercises and turned them into fortification-builders, keeping them fit and active (Birley, 1997). Moreover, he set an example for the soldiers by living in the field with them, sharing their basic military diet, and abolishing luxury from military camps.

Though more desirous of peace than of war, he kept the soldiers in training just as if war were imminent, inspired them by proofs of his own powers of endurance, actually led a soldier’s life among the maniples, and, after the example of Scipio Aemilianus, Metellus, and his own adoptive father Trajan, cheerfully ate out of doors such camp-fare as bacon, cheese and vinegar. And that the troops might submit more willingly to the increased harshness of his orders, he bestowed gifts on many and honours on a few. For he re-established the discipline of the camp, which since  the time of Octavian had been growing slack through the laxity of his predecessors. HA Hadr. 10.2-3

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. 

Sestertius showing Hadrian on horseback haranguing three soldiers, one holding a legionary eagle (Aquila) and the other two with standards. Minted in Rome, AD 130-138. RIC II 920.
© The Trustees of the British Museum (link)
Denarius showing Germania holding spear and resting hand on shield. Minted in Rome, AD 130-138. RIC II 302. Coin from the author’s collection.

It seems very likely that Hadrian went on to inspect the fortifications and troops in the neighbouring provinces of Raetia and Noricum, where he would honour both provinces, raising Augusta Vindelicum (Augsburg) in Raetia as well as several Norican communities to the status of municipium.

Voyage of Hadrian in 121-125.
Map created by Simeon Netchev for World History Encyclopedia and Following Hadrian (CC BY-NC-SA 4.0).

Sources & references:


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