How did Rome physically attempt to defend the Eastern Frontier from 226 to 363?

Diocletian tried to make sure that the eastern frontier was strengthened and defendable against invasions from the empires enemies. The proof of this can be found in an inscription found at Palmyra in the supposed camp of Diocletian. ‘Restorers of the world of whom they are the masters, and leaders of the human race, our lords Diocletian (and Maximianus), unconquered Emperors, and Constantine and Maximianus, noblest Caesars, have established this entrenchment under favourable auspices.’

Upon the death of Diocletian, Constantine came into power in AD337 and continued to make changes, not always to the benefit of defence of the frontier. He expanded his camitatus into a major and permanent force by withdrawing units from the frontier Provinces. He created new units, more cavalry vexillotions and new style infantry units called auxilia. Constantine also appears to have moved the border forces around along the Danube, changing the old-style alae and cohorts with new units of cunei (cavalry) and auxilia (infantry) respectively. These changes by Constantine weren’t seen as a good move by some future historians. Zosimus was scathing in his criticism of Constantine’s forming of the large camitatus, accusing Constantine of ruining Diocletian’s work of strengthening the Eastern Frontier borders defence. ‘By the foresight of Diocletian, the frontiers of the Roman empire were everywhere studded with cities and forts and towers...and the whole army was stationed along them, so it was impossible for the barbarians to break through...But Constantine ruined this defensive system by withdrawing the majority of the troops from the frontiers and stationing them in cities which did not require protection.’

It wasn’t only the increase and deployment of troops which underwent change during these centuries, Roman military fighting equipment was also upgraded and while the basic equipment of the fourth century foot soldier appears to be almost identical to the second century foot soldiers there was some change during the third century, these trends included warmer clothing: as well as the disappearance of the legionary armour and weapons, the infantry took up the equipment which the cavalry had used during the earlier period and the increased use of the heavily armoured cavalry known as cataphrods. While most battles in the fourth century were, as in previous centuries, primarily infantry encounters with cavalry playing a supporting role on the eastern frontier the cavalry played a more prominent role, due to the Persians reliance on cavalry as their main arm. This meant that the Romans had to strengthen their own cavalry element particularly by increasing the amount of cataphracti.’ 

Historian Ammianus gives a description of the armour that the cataphrods and the clibanarii cavalry used, according to Ammianus it was a specialist form of armour. ‘At intervals were mailed cavalrymen, the so-called Ironclads, wearing masks and equipped with cuirasses and belts of steel; they seemed more like statues polished by the hand of Praxiteles than living men. Their limbs were entirely covered by a garment of thin circular plates fitted to the curves of the body.’ Yet Ammianus was less than impressed with these fourth century cavalry, describing three major battles which were actually or nearly lost due to the incompetence or cowardice of the Roman cavalry.’

Not only clothing was changed, but also the helmets and shields, the legionary scutum, a convex rectangular shield disappeared during the third century. All troops adopted the auxiliary oval and sometimes round shields. Examples of these shields have been found at Dura Europos and Nyclam; the new shields were lighter and easier to handle than the earlier Roman shields which had been edged with copper alloy.Along with the change in shields, hand weapons were also upgraded. A weapon known as the spatha which had been used solely by the cavalry was adopted by the infantry. The infantry also gained the use of a heavy thrusting spear, the hasta. The later foot soldier was also able to carry a throwing spear of a spiculum, while the late infantrymen were sometimes known to carry half a dozen throwing darts clipped to their shields. This meant that the later foot soldier had more missile capability than the earlier Principate predecessor.

Defence of the Eastern Frontier changed over the centuries starting ‘with a system of client buffer states and highly mobile legions in the first century AD, shifting to a defensive cordon of more permanent stationary forces on the frontiers in the second and early third centuries, and finally to a system of ‘defence-in-depth’ involving mobile cavalry units and permanent garrisons at points both on and behind the frontiers in the late empire.’ One great supporter of this theory is Edward Luttwak who wrote Grand Strategy of the Roman Empire in 1976, he writes that the defence-in-depth was an acceptance that the Roman frontier provinces themselves would be the main combat zone in manoeuvres against barbarian threats rather than the barbarian lands themselves. With this strategy border forces would not engage a large force, rather they would retreat to fortified forts and wait for mobile troops to come and intercept the invaders, while border troops would be reduced with this method and therefore weaker than other methods, such as under forward defence, the compensation in using the defence-in-depth strategy was the establishment of stronger fortifications to protect themselves.

Luttwak’s theory however has been disputed by other scholars, one of the loudest being B.Isaac author of a leading study of the Roman army in the East written in 1992. It is Isaac’s belief that the empire did not have the modern armies’ equivalent of a general staff to sustain such a strategy; he goes on to claim that the Roman Empire was not interested in defence but was rather ideologically and militarily aggressive up to and including the fourth century.

There’s a difference between the ideologies of an empire and the reality, it was reality that forced Rome to acknowledge the limits of their power and the power of the Roman emperors. There were areas which could be controlled directly, areas which could be influenced and or controlled indirectly and yet other areas that Rome couldn’t and didn’t have any control at all. These areas could be outside the empire or even parts that seemed to be within the very boarders of the Roman Empire, these areas were always in a state of change.

While it’s easy to imagine that the eastern frontier was an ‘immobile structure constrained by hostile and invincible foes’namely the Sasanians and the Parthians, the Romans saw this as a place of opportunities which could be manipulated into a form of defence, leading to diplomatic influence and imperial expansion into ‘Mesopotamia and Armenia, and further north, into Colchis, Iberia and Albania.’ Because the Eastern Frontier was a place where the political and military boundaries of the empire might be influenced by other kinds of religious, spiritual, cultural, economic and social relations, the frontier was more contingent than planned. Meaning allegiances and social interactions from the Roman world into enemy territory both politically and militarily were unavoidable. The Romans would promise to defend their allies from attack by its neighbours while on the allies’ part they would agree not to raid imperial territory while preventing neighbouring tribes from also raiding the Romans. This form of defence continued into the fourth century under Constantine I’s army when they constructed two massive lines of defensive earthworks, 100-250km beyond the Danube.

Not only did the Romans defend their eastern frontier by making allies amongst their neighbouring empires, but by also gaining and keeping control of the rivers. This wasn’t only so that they had an easy way to get the supplies to the troops on the frontier but also as a way to move troops around to their fortified forts. During the Severan period there were ‘notable advances down the Euphrates and into the remote eastern regions of the Province of Arabia.’

To improve defence in the Eastern Frontier old Roman forts were reinforced, and although it’s hard to date any of the structures found, it’s thought that forts with towers are from the later Roman Empire. Forts with four towers were used not only as guard posts but could also be used to send signals to each other and other forts. Some towers were substantial with housing for soldiers, while others were more specifically designed for observation or signalling. Archaeologists have experimented using towers around the Lejjun area, the archaeologists discovered that signals of burning torches could be seen to the fort of Khirbetel-Fityan which could then relay the message onwards to the legionary fortress at Lejjun whose towers cannot be seen, it is these kinds of improvements which helped the Roman army have the edge over any potential hostile forces. These smaller forts were also used as ‘bases for patrols, local administrative centres, watering places, stopovers for travellers and couriers, and guard posts along the routes of communication.’

While new forts were built  it was more usual for old forts to be upgraded to higher defensive specifications, therefore the two parallel ditches which were common around early forts could be joined by excavating the ground between them. The projecting towers were also added. Gates could either be rebuilt with projecting towers or sealed off completely by constructing a large rectangular bastion. Walls were made stronger by doubling the old thickness. The upgraded forts were usually much larger than the newly built forts; newly built forts were rarely over a hectare in size and normally built to fill in the gaps between the old forts and towns.

The debate of whether the Roman emperors and army adopted the defence-in-depth strategy or continued the same posture of forward defence continues the important fact to remember is that whatever the defence strategy, it was less successful in preventing barbarian incursions than the first and second centuries. This may have been due to the heavier barbarian pressure, or because of the practise of keeping large armies and the best troops in the interior, which deprived the broader troops of sufficient support, had become more common. Whatever the reason, it’s clear that while some physical changes occurred which helped keep the Roman Empire intact and safe from the invading barbarians for a few centuries longer, not enough physical change had been achieved. The Romans believed that tradition was everything and were unwilling to change the way in which they fought, failing to compensate for the evolving methods of the Persians and Parthians as well as any other invading enemies. Because of this it was inevitable that the Romans would eventually fall to a stronger empire and not be able to defend their vast territories.

BIBLIOGRAPHY

Primary Sources: Works Cited

Ammianus M (1986),  The Later Roman Empire (AD 354-378) - London : Penguin Books.

Zosimus , (5th century )Historia Nova.

Secondary Sources: Works Cited

Bishop M.C & Coulston J.C.N (2006)Roman Military Equipment from the Punic Wars to the Fall of Rome 2nd Ed - UK : Oxbow Books limited.

Butcher K(2003) Roman Syria and the Near East - London : British Museum Press.

Cameron A(1993) The Later Roman Empire - Oxford : Fontana Press.

Dodgeon M & Lieu, S (1991 Repr1994)The Roman Eastern Frontier and the Persian Wars - London : Routledge.

Elton H(1996) Warfare in Roman Europe AD 350-425 - Oxford : Oxford University Press.

Goldsworthy A (2003) Complete Roman Army - UK : Thames and Hudson.

Goldsworthy A (2000) Roman Warfare - UK : Cassell: Wellington House.

Isaac B (1990)The Limits of the Empire, The Roman Army in the East - Oxford : Oxford University Press.

Jones A.H.M(1964) Later Roman Empire - U.S.A : University of Oklahoma Press.

Luttwak E (1976)The Grand Strategy of the Roman Empire - London : Widenfeld and Nicholson.

Thompson G (1979) Die Oracula Sibyllina - New York : Arno Press.

 Tomlin R.S.O & Wacher,J (Ed)(1987) The Army of the Late Empire in the Roman World - London : [s.n.]

Other Refrences:

  Freeman, P & Kennedy, D (ed)(1986). ‘The Defence of the Roman and Byzantine East’: British Archaeological Reports, S297, 2 vols: Oxford

Kennedy, D & Riley, D (1990)‘Rome's Desert Frontier from the Air’: Batsford Limited, London

Lee, A.D (1993) ‘Information and Frontiers, Roman foreign relations in late antiquity’: Cambridge University Press, Cambridge

Oates, D (1968) ‘Studies in the Ancient History of Northern Iraq’: British Academy, Oxford

 Whittaker, C.R (1994): ‘Frontiers of the Roman Empire-A Social and Economic History’ : Johns Hopkins University Press, Baltimore

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