The Imperial frontiers of the Roman Empire

In this week’s blog post I will be investigating the Imperial frontiers of the Roman Empire from the first to fifth centuries AD. I will be looking at the placing of the frontiers, what constituted a frontier and how successful they were at keeping the enemies of Rome at bay. The Roman Empire expanded from western and central Europe in the North West to the lands in the east of Egypt and Parthia. These territories, built up over hundreds of years needed protecting and a well placed natural or man-made bounder was the most efficient solution compared with the large costs of a standing army. Though first we must ask what it is meant by a frontier in general terms. On the one hand they kept the Empire together and ensure the protection of its citizen in the event of an attack. However they also kept ‘others’ out both physically and psychologically. A wall, a hedge or even lines painted on the ground can be a boundary intending to keep someone out and asserting ownership over an area of land. Simply, a boundary told a person where their land stopped and where someone else’s began. These boundaries also needed to be visible and to have a meaning in their construction. The construction and impression of a boundary presents an image of power and security, one such picture that the Roman Empire achieved in their control of the lands in the Empire.

Firstly, where were these frontiers placed? The most impressive and well-known Roman frontier lies in the north of the Empire at Hadrian’s Wall. The Emperor Hadrian ascended to the Imperial seat in 117 AD, with the death of his predecessor Emperor Trajan. It was under Trajan that the Empire’s expansion reached its height and it was Hadrian’s decision to begin consolidating these areas. Whilst the Britons had largely been subdued over the last century of Roman conquest, the Celtic people still fought with Rome in northern England. Raids by the Picts presented a constant danger to the Roman citizens and legions based in Britain and therefore it was decided that a wall should be built to consolidate the edge of the Roman World. Running for 80 Roman or 73 British miles (117 km) and with a height of 7-10 ft, Hadrian’s Wall was finished in 124 AD with various forts and stations soon built afterwards to bolster its defence. From this example it is clear that the frontiers, at least in the north of the Empire, were built at the limits of Roman control. Supported by varied and uneven terrain the Wall in the north served as boundary for the Empire until Rome’s retreat from Britain.

Frontiers could also be placed where no artificial boundaries could be placed and the natural elements and landscape could serve as a defence. In the south-east of the Empire, the deserts of Africa served as the limits of the Roman Empire. With Egypt annexed under the reign of Emperor Augustus around 30 BC, the Empire now controlled a vast wealthy area of land with the Nile River at its centre. However apart from a few cohorts and forts inside Egypt, the province was lightly guarded. As it was mainly accessible through the Mediterranean and up the Nile, its protection handled by the Imperial Navy, and surrounded on land on most sides by the Sahara desert, Egypt and the rest of Africa was well defended in the south. Whilst I have only briefly looked at Egypt, the desert frontier protected the Roman Empire’s African interests without much difficulty. Derek Williams hints at another reason why the edges of the Roman Empire were loosely defended, that of internal dangers. The Empire had been wrecked beyond counting from civil wars and by placing fewer soldiers and their commanders at their limits; they could hope to limit the number men seeking to elevate themselves when not under the eyes of their superiors.

Therefore both natural and artificial defences constituted a frontier for the Roman Empire and they both served as a way of controlling who entered and left the Imperial territories. Depending on the time period and the political setting, the Roman frontiers generally held against those who would seek to attack Rome. What was crucial to the frontiers success however, was for the Empire and those who administrated it to remain focused on its defence. This was a difficult motion to continuously follow as the various civil wars were played out, with one emperor replacing another prove. Whilst the frontiers held the Roman Empire together another process was occurring that in many ways secured, not just the Roman world but the Latin world, when the Empire eventually fell. Romanization unified the cultures and peoples within the Roman Empire under central laws, religions etc and served to protect the ideas that held Rome up for over five centuries. The frontiers were a success because they allowed this process to flourish as each border was a meeting point between one culture and another. Alongside this boundaries trade flourished and the Roman way of life was spread further than any frontier could hope to extend to. Therefore, whilst the frontiers served as images of power and spectacle for the Roman Empire, they really stood and represented the very limits of Roman control. As a cost-effective means of protecting an incredibly large and culturally diverse Empire, the Roman frontiers serve their purpose to maintain the Empire’s coherence. The extent of the Roman Empire, roughly 4,000 miles, means that there was more than I could handle in this blog post so my apologies but I hope this has been interesting for our blog readers.


Derek Williams, The Reach of Rome, A History of the Roman Imperial Frontier 1st-5th Centuries AD (London, 1996).

Stephen Johnson, Hadrian’s Wall (London, 1989).

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