Danube Limes


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Mar 8, 2013
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Danube Limes – History and War (wordpress.com)

After Roman conquest of Illyricum, conflicts are nearly constant on its borders. From 1st to 4th century AD, there are conflicts with Sarmatians on the Danube, especially along the Lower Pannonian limes. During the reign of Domitian, Pannonia saw the deployment of legions XIV Gemina and XXV Rapax, latter of which is completely destroyed in the conflict and replaced by II Auditrix. In 105., emperor Trajan conquered Dacia, dividing Pannonia into Upper and Lower Pannonia. From Trajan’s reign onwards there are continuously four legions deployed in the Pannonia.In mid-2nd century, Iaziges attacked the Pannonian limes somewhere to the south of Aliska, and there may have been battles in vicinity of Mursa as well.

During the reigns of Marcus Aurelius and Commodus, Danubian provinces are invaded by the Marcommanes, Quades and Iasiges. Barbarians move through Pannonian plain towards the Julianic Alpes. They enter Italy and besiege Aquileia, devastating Mursa along the way. Marcus Aurelius leads two campaigns. During the first campaign, from 172. to 175., he defeated the barbarians. Marcus Aurelius builds a number of castella on Danube and reinforces Danube fleet, while also settling defeated peoples within the Empire. He however dies during his second campaign, led during 177 AD.

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From third century AD, Roman Empire becomes an open military dictatorship, with complete disregard for Senate which Principate still had pretended to respect. Concurrently, importance of Danubian limes and Danubian legions grows.

Phillip the Arab’s reign sees the loss of Dacia to Carps, which puts Pannonia in even greater danger. Gallienus allowed Marcommans to settle part of Upper Pannonia, while Aurelian pushed Vandals, Suebes and Sarmatians out of Pannonia. Probus settled large groups of barbarians as coloni near Danube, while main enemies are Goths and Sarmatians. From Maximinus Thrax to Aurellianus, the Empire is in a steep downward slide, despite all the efforts to stop it. Diocletian’s reforms managed to halt the decline, but the Western Empire still slowly falls apart over the next two centuries. As a part of Diocletian’s reforms, Pannonia was split into four smaller provinces: Upper Pannonia was split into Pannonia Savia and Pannonia Prima, while Lower Pannonia was split into Pannonia Secunda and Pannonia Valeria.

After death of Constantine the Great in 337 AD, area around Mursa became a battlefield between Magnentius and Constantius II. Constantius won, and in 357. – 359. he is again in Mursa due to war against Quads, who are ravaging Valeria, and Sarmatians, who are ravaging Upper Moesia and Valeria Secunda.

Valentinian I restored the limes and repaired the roads and fortifications along the Rhine and Danube. But Quads and Sarmatians penetrated into Panonia, and Valentitian I died there receiving their emissaries.

Following Valens’ defeat at Adrianople in 378., he was succeeded by Theodosius who split the Empire into Western and Eastern halves. Pannonia was increasingly under attack, and coin mint in Sirmium ceased operation. In 406., Valeria is apparently surrendered to the Huns. Pannonia Prima, Savia and Secunda are in 427. surrendered to Eastern Empire, only to be soon captured by the Huns, who in 441. conquered Sirmium and the Eastern Empire’s Pannonian possessions.

Nature of Limes
Limes is a Latin word which means a “set, defined border”. This border could be a path, a road, a wooden fence, a drywall, or a hedge. In modern world, however, the world “limes” most often is used to denote a fortified border of the Roman Empire, or else the system of border fortifications itself.

In most cases, limes consisted of weak or no fortifications – massive fortifications such as Hadrian’s wall were an exception, and majority of the border was set on natural barriers such as rivers. Fortifications along the border were connected by a frontier road which ran along the border, and indeed gave border defences their name (limes was a term for a border road). In the Eastern deserts, border was defined by the road itself. Man-made walls were only built where natural barriers were deemed insufficient. Border defences themselves were a very complex system. Defences at border itself were used primarily as a border control, most often for the purposes of collecting customs duties. These included a combination of border walls, watchtowers and riverine vessels. Slightly in the rear were located smaller forts manned by auxilliaries, which were used to intercept minor incursions. Legionary forts were even further back, and were pulled further and further into the interior as increased frequency and size of incursions necessitated forming larger field armies to counter them.

Reconstruction of a guard tower
The main defensive function of the limes was deterrence: any attacker who breached the border would soon find himself faced with a large, well-equipped and well-trained Roman army. Even if the attackers were able to find and loot a city before then, they would still be massacred on the way home. And any incursion into the Roman territory would soon be followed up by Roman retaliation against the native population, with limes forts likewise serving as a basis for this retaliation.

But limes was not a solely defensive construct. Border fortifications could be used as a springboard for further conquest, and as a way to keep watch over border tribes. Rivers that formed parts of the border were major traffic arteries, which increased importance of limes forts for Roman tax collection. In fact, the primary purpose of the limes was control of movement to and from the Empire.

Limes was also not the limit of Roman authority. While it did form a limit of direct Roman rule, Romans attempted – and often succeeded – in establishing their political dominance over nearby tribes outside the Empire. These tribes then served as a first line of defense, acting as informants and an advance guard. In this, impressive fortifications often present served an important function in overawing the barbarians, demonstrating the Roman might and influence and thus making any prospect of attack much more daunting. Loyalty was also bought through luxurous presents to chiefs of border tribes.

Danube Limes
Romans had divided the entire area between Adriatic and the Danube into Upper and Lower Illyricum, with latter closer to the Danube. Only Emperor Claudius’ conquest established the centuries-lasting border on the Danube. Organization of the limes was work of the 2nd century Emperors, Trajan and Hadrian.

Limes itself consisted of a complex of fortified cities, forts and watchtowers, connected by a road. While forts did not usually have a direct line of sight to each other, a dense line of watchtowers allowed for quick transfer of messages. Initially, however, there was not much of a defense system. First military installations in the newly conquered Danubian provinces were built along the main roads from Italy to the edges of the Empire. Forts and other fortifications along the Danube were only established at sensitive areas such as river confluences and major trade routes, while river itself appears to have been controlled mainly by the fleet. Over the next two centuries, the need for defense and also intervention in the barbaricum led to establishment of legionary bases at Regensburg (Germany), Enns, Vienna and Carnuntum (Austria), Komarom and Budapest (Hungary), Belgrade and Viminacium (Serbia), and in Gigen, Novae and Silistra (Bulgaria).

reconstruction of a fortress at Novae
Danube was one of most important areas of the Roman border, and thus received special attention. Defences of Danube consisted of hundreds of fortifications, including at least 12 legionary forts, more than 200 auxilliary forts, and hundreds of watchtowers. River itself was an excellent line of defense. It was wide and deep, which meant any crossing had to be made by boat. Border forts were dense – located some 10 to 30 kilometers away from each other, while watchtowers were located 1 – 2 kilometers apart. More than 200 stone watchtowers from Late Empire are recorded along the Danube banks in Hungary alone. The road followed the river closely, except in places where terrain was unsuitable for construction. In such cases it swung to the hitherland, with byroads connecting it to forts and watchtowers. Some of the major forts were located at Carnuntum (Austria), Aquincum (Budapest, Hungary), Viminacium (near Belgrade, Serbia), and Novae (Svistov, Bulgaria).

Due to the width of the river, navy played an important part in protection of the limes – river was the first and most significant barrier to incursions. Its role was only increased by the fact that Danube was an important trade and supply artery, allowing trade between cities as well as easy resupply of military units stationed along the river. Because of this, many forts near Danube included the shipbuilding and harbour facilities. Romans, as a rule, did not maintain bridges over the Danube, and so ships and boats were the only practical way of crossing the river. Forts themselves also acted as checkpoints to control traffic in and out of the Empire.

Castrum of Canabae
Following the conquest of Dacia in AD 106, limes between Viminacium and Belene lost its purpose, but was repaired as the Romans withdrew from Dacia in AD 270/275. Many forts were also attacked and destroyed during the Marcommanic Wars of 166 – 183., and hitherland – which provided an important source of supplies and recruits – was also raided. Barbarians were finally defeated in 183.

In third century, constant civil wars led to neglect of the limes. Instead, fortifications and garrisons are transferred to depth of the Roman territory, and many internal fortifications are strenghtened. Limes is restored during the emperor Diocletian and then Valentian, only to finally collapse in the seventh century.

Capidava site in Romania
Still, Eastern Roman Empire maintained some kind of limes as long as it controlled a bank of Danube. As the original system melted away, it was replaced instead by a system of fortified towns and strongpoints. This system itself fell apart during the next wave of great migrations, when invading tribed devastated and then conquered Balkans all the way to Greece and walls of the Constantinople itself. Yet some system of fortifications was maintained until 1204.

It is likely that Valentinian and Valens undertook reconstruction work on a large scale due to Gothic threat. Yet the archeologically most obvious phase is the period of destruction and fire following the battle of Hadrianople.

In the following period, border was protected by the foederati, who built the wattle and daub homes. This lasted until mid-5th century, when Hunnic invasion caused disaster. Frontier in Noricum and Pannonia broke down under Hunnic attacks, and was abandoned in 487/88 AD. Fortifications, including most fortresses, were burnt to the ground, and were only restored under Justinian I. Justinian’s fortifications retained the disposition of fortifications from the former Roman frontier, though fortifications themselves were updated and, at places, newly constructed to keep up with increasing defensive demands.

Fortresses can be divided into:

  1. Renovated Roman auxiliary and other minor forts.
  2. Renovated late Roman burgus – forts (from the Diocletian and Constantine periods).
  3. New early Byzantine forts built around renovated late Roman burgus-forts.
  4. Completely new early Byzantine forts
After the Hunnic invasion of 443., forts were not repaired until the early sixth century, when all the auxilliary bases on limes were renovated. Former Roman forts were for the most part renovated based on their original plans. Most significant alteration was closing off of the gates. Second category of renovations included simply reinforcing the walls, making them thicker. Last group are Justinianic castella which were completely new constructions. In almost all of the Justinianic fortresses a layer of ash and destruction debris can be observed, dating to forceful Slavic incursion of 580 AD. While forts were renovated after passage of the crisis, they were finally and definitely destroyed by combined forces of Slavs and Avars in 596 AD.
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