Military Architecture as a Symbol and Object of Intimidation
Roman fort gates along the frontiers of the Roman Empire could reach considerable heights of more than 20 metres. Taking into account the local topography of sites (with forts often situated on landscape terraces) the perception was that they were even higher than in reality and they therefore must have created a considerable impression. The representational aspect is true also for the Limes running straight through the “Barbarian wilderness”: this “rigor valli”, which is to be found on various sections of the frontier and was immortalized on contemporary souvenir objects, was a clear message to barbarians: “see what our military force can achieve!”
To protect communications and movement in the frontier zone
This contribution to the debate focuses on frontiers in North Africa to argue that one of the primary functions of military installations there was to protect people travelling in and through the frontier zone.
Successive frontiers in Mauretania Caesariensis were characterised by linear deployments whereby the bulk of the provincial army was stationed along one principal highway which extended for most of the length of the province. This formed a pragmatic response to the elongated shape of Mauretania Caesariensis, ensuring the presence of units able to provide military coercion in all parts of the frontier zone, but secure communications between and movement of supplies to these widely spread units was obviously crucial. The second-century deployment seems to have taken shape during the reigns of Hadrian and Trajan. In addition to the garrison forts, watch towers are known along certain section of the highway. However, rather than marking a frontier line, with the purpose of controlling access into Roman territory, however, these towers are most convincingly interpreted as providing protection for soldiers, officials and others travelling along the highway. It is noteworthy that the known examples are located in areas of rugged terrain where travellers would have been particularly vulnerable to ambush. These were tempting ‘high value’ targets for bandits or disaffected tribesmen. It is likely that the same pattern prevailed when the army moved south to the so-called nova praetentura at the beginning of the third century.
Finally a case can be made that at least one of the longer frontier barriers in the Numdian frontier zone – the Mesarfelta-Tubunae barrier – was at least partly designed to shield transhumant pastoralists from robbery and rustling in rugged hill country and narrow gorges, during their seasonal journeys from the pre-desert to the better watered Tell and back.
The defensive purpose of Roman frontiers
The weakness of their cavalry exposed the Nervii, a tribe in northern Gaul, to raids by their neighbours. To secure their borders, they planted impenetrable thorny hedges, making quick raiding missions much more difficult (Caesar, Gallic War, 2.17). The Germanic Angrivarii erected a linear barrier to protect their tribal lands, where there were no natural barriers. They used this to take a stance against the Roman army who succeeded in storming it only with difficulties (Tacitus, Annals 2.19-20). A simple tribal barrier could be effective against the might of a mega-empire. Hadrian’s Wall and the Antonine Wall occupied, where possible, high ground, and the same is true for late antique Persian walls – all no doubt more difficult to overcome than the basic tribal barriers cited. There are cases of simple linear earthworks proving decisive in war, even in the age of firearms, as late as the eighteenth century. Whilst it is obvious that the prime function of massive investment in border defence was tangible and real military advantage in deterring, decimating, delaying and trapping the enemy – fashion has led modern scholarship to dismiss linear barriers as largely symbolic and not very effective. Mohammad Chaichian (Empires and Walls, 2014), examining Hadrian’s Wall and other long walls from antiquity to modernity (some of them operational for centuries) concludes that they ‘always signal the fading power of an empire’. President Trump’s wall-building ambitions have only reinforced the view that past and present defensive walls are mere follies (Chris Catling, Current World Archaeology 83, 2017: 58). More moderate sceptics acknowledge some benefits, but doubt that any Roman walls ever served as fighting platforms, the army preferring to fight in the open. Yet, no sensible general will put his troops into unnecessary danger. Where terrain and walls could be used to minimise or avoid casualties, it made no sense to raise one’s head above the parapet. It is time to tell the unfashionable and simple truth again. Roman walls were no vanity projects, but were built to reduce raiding and make invasion much more difficult and costly, thus protecting the prosperity of the hinterland. And, as long as adequately manned, they largely succeeded in doing so.
To control transhumance
On the basis of the archaeological evidence of High Imperial and Late Roman frontier installations in the steppe regions of the Near East and on the fringes of deserts in North Africa the paper will argue that the main purpose of Roman Frontiers was to control transhumance