Danube Frontier system (or Limes Moesiae)
Limes Moesiae and other linked Roman walls

The Moesian Limes (Latin: Limes Moesiae) is the modern term given to a linked series of Roman forts between the Black Sea shore and Pannonia (present-day Hungary) along the Danube. It was the eastern section of the so-called Danubian Limes[1] and protected the Roman provinces of Upper and Lower Moesia south of the river. The eastern section (today in Romania) is often called the limes Scythiae minoris[2] as it was located in the late Roman province of Scythia Minor.

In addition the term Limes Moesiae may be used to include many other linked lines of defence were established in the region in different periods and later abandoned in favour of others depending on the military situation.

Map of Roman provinces


See also: List of castra by province and List of castra in Romania

The Limes Moesiae[3] includes essentially the linked forts and stations along the Danube from Singidunum (Belgrade) to the mouth of the Danube on the Black Sea.[4] It was not fortified with palisades or a boundary wall but the forts were linked by a road and included eight legionary fortresses, many forts for auxiliary troops and watch/signal towers. The legionary fortresses included:

Other forts on the Danube limes included:

The frontier was divided into two major sections by the river Iskar at Oescus which also marked the border between the provinces of Moesia Superior and Inferior.

The narrowness of the river at Djerdap formed a barrier between north-west and north-east Moesia that was difficult to overcome, initially making communication between the Pannonian and the Moesian armies difficult. This problem was solved only by the construction of a 3m wide road under Trajan, who had the Legio VII Claudia chisel into the rock walls replacing a wooden towpath construction that was susceptible to damage by drift ice. Other improvements for shipping included the construction of a canal near Novi Sip to avoid the dangerous rapids and shoals there. The two ends of the canal were secured with forts. The best-known building on the Moesian Limes was Trajan's Bridge at Drobeta/ Turnu Severin from the early 2nd century AD, the first permanent bridge connection across the lower Danube which was also guarded on both banks by forts.

The Limes Moesiae may also include, depending on authors:

Many of these walls consisted of earth ditches, 3 m high and 2 m wide, and similar to the Antonine Wall.

The Limes was used by non-Roman kingdoms after the 5th and 6th century and partially rebuilt and increased.[6]


Further information: Bastarnae

Once Augustus had established himself as sole ruler of the Roman state in 30 BC after the battle of Actium, his strategy was to advance the empire's south-eastern European border from Macedonia to the line of the Danube. The main objective was to increase strategic depth between the border and Italy and also to provide a major river supply route between the Roman armies in the region.[7] The lower Danube was given priority over the upper Danube and required the annexation of Moesia. It was therefore necessary to conquer the tribes who dwelt south of the Danube namely (from west to east) the Triballi, Moesi, Getae and the Bastarnae who had recently subjugated the Triballi, and with their capital at Oescus.[8] Augustus also wanted to avenge the defeat of Gaius Antonius at Histria 32 years before and to recover the lost military standards held in the powerful fortress of Genucla.[9]

Marcus Licinius Crassus, grandson of Crassus the triumvir was appointed for the task. He was an experienced general at 33 years of age, and proconsul of Macedonia from 29 BC.[10] After a successful campaign against the Moesi, he drove the Bastarnae back toward the Danube and finally defeated them in pitched battle, killing their King Deldo in single combat.[11] Augustus formally proclaimed this victory in 27 BC in Rome but blocked Cassius' entitlement to the Spolia opima and use of the term imperator apparently in favour of his own prestige.

Legion IV Scythica was initially stationed in Moesia (probably at Viminacium) to counter threats from neighbouring Thrace and aggressive peoples north of the Danube. Auxiliary and smaller forts for vexillations of these legions were built along the Danube to form the Limes Moesiae. At this stage forts on the frontier consisted of earth walls with wooden palisades.

At the end of 85 or the beginning of 86 AD the Dacian king Duras attacked Moesia and caught the Romans by surprise since the governor, Oppius Sabinus, and his forces were annihilated.[12] Domitian replaced the wood and earth walls of Danubian forts by stone walls just before Domitian's Dacian War in 87 AD (e.g. at Taliata) when accompanied by Cornelius Fuscus, Prefect of the Praetorian Guard, he personally arrived in Moesia with legions Legio IV Flavia Felix from Dalmatia, Legio I Adiutrix and Legio II Adiutrix and eventually cleared the invaders from the province.

In the winter of 98/99 AD Trajan arrived on the Danube, quartered at the Diana fort near Kladovo, and started Dacian war preparations on the Iron Gates gorges. He extended the road in the gorge for 30 miles, as he stated on the well-known inscription of 100 AD. In 101 he also cut a canal nearby, as he also recorded on a marble plaque which reads:

“because of the dangerous cataracts he diverted the river and made the whole Danube navigable”: (ob periculum cataractarum, derivato flumine, tutam Danuvii navigationem facit).

Trajan restored stone defences in the area and rebuilt all earthworks in stone. Just below the Pontes fort a large port and massive horrea were built.

Between the first and second Dacian wars, from 103 to 105, the imperial architect Apollodorus of Damascus constructed Trajan's Bridge one of the greatest achievements in Roman architecture.

Full military occupation of the plain between the Carpathian foothills and the Danube may already have occurred by the end of Trajan’s First Dacian War (101/102). The majority of forts here, however, were established after the final conquest of the Dacian kingdom in 106 AD. The abandonment of Moldova and the creation of the Limes Transalutanus can both be tentatively dated to the reign of Hadrian.

After a long period of peace Septimius Severus reconstructed the Moesia Superior defences and under Caracalla more reconstruction was done as can be seen at Pontes where, as with many other Iron Gates forts, the original layout was supplemented with the gates and towers. A new fort was built on an island at the Porečka river.

The Roman abandonment of Dacia probably occurred during the reign of Gallienus (260-68), before the traditional date of around 275 when Aurelian established the new province of Dacia south of the Danube (Cătăniciu 1981, 53-55).

In the Late Roman period, the extent of control and military occupation over territory north of the Danube remains controversial. One Roman fort (Pietroasa de Jos), well beyond the Danubian Limes and near Moldavia, seems to have been occupied in the 4th century AD, as were bridge-head forts (Sucidava,[13] Barboşi, and the unlocated Constantiniana Daphne) along the left bank of the river. In this Roman fort, built by Constantine I, researchers found a thermae building.[14]

The "Brazda lui Novac de Nord" (or "Constantine Wall") has been shown by recent excavations to date from emperor Constantine around 330 AD,[15] at the same time as the "Devil's Dykes" (or "Limes Sarmatiae"), a series of defensive earthen ramparts-and-ditches built by the Romans between Romania and the Pannonian plains.[16]

Similarly, although considered 1st century and believed to predate the Limes Transalutanus, the function and origins of a shorter section of bank and ditch known as the "Brazda lui Novac de Sud" remain uncertain. The absence of any evidence for Late Roman forts or settlements along its course and south of it rather suggests a later, probably medieval, date.

The fortification line erected by the king of the Thervings Athanaric, between the banks of river Gerasius (modern Prut) and the Danube to the land of Taifali (modern Oltenia), probably reused the old Roman limes called Limes Transalutanus[17]


Map of the "Roman" Walls north of the Danube delta

There is a controversy over the historical perspective of who built the earth dykes: the Romans, the Byzantines or others:

See also


  1. ^ Frontiers of the Roman Empire – The Danube Limes (Bulgaria) https://whc.unesco.org/en/tentativelists/6474/
  2. ^ Frontiers of the Roman Empire - The Danube Limes (Romania) https://whc.unesco.org/en/tentativelists/6446/
  3. ^ ROMAN FRONTIER WITHIN THE CROSS-BORDER REGION ROMANIA-BULGARIA https://danubelimes-robg.eu/index.php/en/
  4. ^ R. Ployer, M. Polak, R. Schmidt, The Frontiers of the Roman Empire. A Thematic Study and proposed World Heritage Nomination Strategy, Vienna/Nijmegen/Munich, 2017, p. 41, 75-6
  5. ^ https://vici.org/vici/36068/
  6. ^ Romans in eastern Romania (in Romanian)
  7. ^ Res Gestae 30
  8. ^ Ptolemy
  9. ^ Dio LI.26.5
  10. ^ Dio LI.23.2
  11. ^ Cassius Dio 51.23.3 ff. [1]
  12. ^ Mócsy (1974), p82.
  13. ^ Sucidava photos
  14. ^ Archeological research about Romans in Romania during the 3rd and 4th centuries (in Romanian)
  15. ^ Wacher. The Roman world p.189
  16. ^ Map showing the Roman fortifications in the 4th century
  17. ^ The Goths By Peter Heather page 100
  18. ^ J. S. Wacher. The Roman world p.190
  19. ^ Heather, Peter. The Goths p. 100