Claustra Alpium Iuliarum
Encyclopedia
Claustra Alpium Iuliarum (Latin: "Barrier of the Julian Alps
") was a defense system within the Roman Empire
between Italia and Pannonia
that protected Italy from possible invasions from the East. It secured the Postojna Gate
, the land link between the eastern and western part of the empire, and thus the Claustra represented an inner border defense of the empire. Contrary to a linear limes
the Claustra consisted of a series of interconnected fortifications with its center at Ad Pirum at todays Hrušica
.
took place threatening the Roman heartland. Subsequently, in order to protect Italy, a series of walls and fortifications were gradually erected around the area of the strategic Postojna Gate. Most of the construction was done after 284 under Diocletian
and Constantine I
. Although this development was done subsequent to a major invasion of Northern Italy by the Alemanni in 271, Whittaker indicates that inner fortification lines were primarily aimed to secure the internal stability of the empire rather than keeping barbarian
s out. The fortification system included Forum Iulii (today Cividale del Friuli
), Tarsatica (today Rijeka
) and followed the valley of the Idrijca
river. It stretched over the Postojna Gate to the hills south of Aemona (today Ljubljana
).
In-depth fortifications along the Roman road started at Castra ad fluvium frigidum (today Ajdovščina
) and ended at Nauportus (today Vrhnika
). The central hill fortress of Ad Pirum was typically manned with 500 soldiers but could keep up to 100,000 soldiers. Ad Pirum’s walls were unearthed by Austrian and Italian archeologists and shown to be at a height of 8 m and a thickness of 2 m; the wall towers were 10 m high.
took Ad Pirum during his fight against his challenger Magnentius
. Most importantly, the Battle of the Frigidus
took place in 394 between Castra and Ad Pirum. In this battle the eastern emperor Theodosius I
prevailed over his western rival Eugenius
and by his victory secured Christianity as the main religion of the empire.
After the 5th century the Roman fortifications fell into disrepair. Today selected sections have been restored by archeologists.
Julian Alps
The Julian Alps are a mountain range of the Southern Limestone Alps that stretches from northeastern Italy to Slovenia, where they rise to 2,864 m at Mount Triglav. They are named after Julius Caesar, who founded the municipium of Cividale del Friuli at the foot of the mountains...
") was a defense system within the Roman Empire
Roman Empire
The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....
between Italia and Pannonia
Pannonia
Pannonia was an ancient province of the Roman Empire bounded north and east by the Danube, coterminous westward with Noricum and upper Italy, and southward with Dalmatia and upper Moesia....
that protected Italy from possible invasions from the East. It secured the Postojna Gate
Postojna Gate
The Postojna Gate , also Adriatic Gate and Italo-Illyrian Gate, is a major mountain pass of the Dinaric Alps. Located in Slovenia, the pass's approximately wide saddle allows for the lowest crossing of the Dinaric Alps, at an elevation of . and a second higher crossing at the Hrušica plateau. It...
, the land link between the eastern and western part of the empire, and thus the Claustra represented an inner border defense of the empire. Contrary to a linear limes
Limes
A limes was a border defense or delimiting system of Ancient Rome. It marked the boundaries of the Roman Empire.The Latin noun limes had a number of different meanings: a path or balk delimiting fields, a boundary line or marker, any road or path, any channel, such as a stream channel, or any...
the Claustra consisted of a series of interconnected fortifications with its center at Ad Pirum at todays Hrušica
Hrušica (plateau)
Hrušica is a plateau at the northern end of the Postojna Gate. The plateau can be viewed as the end or extension of the Trnovski gozd, to the west is the Nanos mountain. The limestone plateau reaches an altitude of 1,080 m, while the road crosses it at 883 m...
.
Development
In the year 6 the Great Illyrian RevoltGreat Illyrian revolt
The Great Illyrian Revolt, was a major conflict between an alliance of indigenous communities from Illyricum and Roman forces that lasted for four years beginning in AD 6 and ending in AD 9.-The war:...
took place threatening the Roman heartland. Subsequently, in order to protect Italy, a series of walls and fortifications were gradually erected around the area of the strategic Postojna Gate. Most of the construction was done after 284 under Diocletian
Diocletian
Diocletian |latinized]] upon his accession to Diocletian . c. 22 December 244 – 3 December 311), was a Roman Emperor from 284 to 305....
and Constantine I
Constantine I
Constantine the Great , also known as Constantine I or Saint Constantine, was Roman Emperor from 306 to 337. Well known for being the first Roman emperor to convert to Christianity, Constantine and co-Emperor Licinius issued the Edict of Milan in 313, which proclaimed religious tolerance of all...
. Although this development was done subsequent to a major invasion of Northern Italy by the Alemanni in 271, Whittaker indicates that inner fortification lines were primarily aimed to secure the internal stability of the empire rather than keeping barbarian
Barbarian
Barbarian and savage are terms used to refer to a person who is perceived to be uncivilized. The word is often used either in a general reference to a member of a nation or ethnos, typically a tribal society as seen by an urban civilization either viewed as inferior, or admired as a noble savage...
s out. The fortification system included Forum Iulii (today Cividale del Friuli
Cividale del Friuli
-External links:*...
), Tarsatica (today Rijeka
Rijeka
Rijeka is the principal seaport and the third largest city in Croatia . It is located on Kvarner Bay, an inlet of the Adriatic Sea and has a population of 128,735 inhabitants...
) and followed the valley of the Idrijca
Idrijca
The Idrijca is a river flowing through the Idrija Hills and Cerkno Hills. It is 60 km long. It rises near Vojsko, flows towards northeast and after passing through Idrija turns to the northwest. After passing through Spodnja Idrija and Cerkno it joins the Soča in Most na Soči.The river basin...
river. It stretched over the Postojna Gate to the hills south of Aemona (today Ljubljana
Ljubljana
Ljubljana is the capital of Slovenia and its largest city. It is the centre of the City Municipality of Ljubljana. It is located in the centre of the country in the Ljubljana Basin, and is a mid-sized city of some 270,000 inhabitants...
).
In-depth fortifications along the Roman road started at Castra ad fluvium frigidum (today Ajdovščina
Ajdovšcina
Ajdovščina is a small town and a municipality with the same name and a population of 7000 , located in the Vipava Valley , Slovenia....
) and ended at Nauportus (today Vrhnika
Vrhnika
Vrhnika is a town and a municipality in Slovenia. It is situated on the Ljubljanica River, 21 km from Ljubljana along the A1 motorway.-History:...
). The central hill fortress of Ad Pirum was typically manned with 500 soldiers but could keep up to 100,000 soldiers. Ad Pirum’s walls were unearthed by Austrian and Italian archeologists and shown to be at a height of 8 m and a thickness of 2 m; the wall towers were 10 m high.
Battles
Castra Alpium Iuliarum saw a number of battles. Early fortifications may have been useful in 169 when the Marcomanni attempted to enter Italy but proved inadequate when the Alemanni invaded Italy in 271. In 351 Constantius IIConstantius II
Constantius II , was Roman Emperor from 337 to 361. The second son of Constantine I and Fausta, he ascended to the throne with his brothers Constantine II and Constans upon their father's death....
took Ad Pirum during his fight against his challenger Magnentius
Magnentius
Flavius Magnus Magnentius was a usurper of the Roman Empire .-Early life and career:...
. Most importantly, the Battle of the Frigidus
Battle of the Frigidus
The Battle of the Frigidus, also called the Battle of the Frigid River, was fought between September 5–6 394, between the army of the Eastern Emperor Theodosius I and the army of Western Roman ruler Eugenius....
took place in 394 between Castra and Ad Pirum. In this battle the eastern emperor Theodosius I
Theodosius I
Theodosius I , also known as Theodosius the Great, was Roman Emperor from 379 to 395. Theodosius was the last emperor to rule over both the eastern and the western halves of the Roman Empire. During his reign, the Goths secured control of Illyricum after the Gothic War, establishing their homeland...
prevailed over his western rival Eugenius
Eugenius
Flavius Eugenius was an usurper in the Western Roman Empire against Emperor Theodosius I. Though himself a Christian, he was the last Emperor to support Roman polytheism.-Life:...
and by his victory secured Christianity as the main religion of the empire.
After the 5th century the Roman fortifications fell into disrepair. Today selected sections have been restored by archeologists.