Signalling and the Design of the Antonine Wall

Abstract

THE DEVELOPMENT OF THE WALL S urveys by the writer in Britain and Germany 1 have recently revealed a consistent pattern of Roman frontier communications in which each system's minor installations were sited so as to be able to see, and thus to signal to, their nearest fort, whilst the forts themselves could be linked to form a unified chain. But, until recently, the Antonine Wall appeared so different that it seemed unlikely that it operated in the same way. Comparing the two British Walls, both share the basic framework of a rampart and ditch and the change from stone to turf construction, on the northern system, is mere detail, but differences in the garrison installations did seem to have been of operational importance. For example, the inter-fort spacings of the Antonine Wall were much shorter, varying from 1.56 to 3 Roman miles, as against 6 to 9 on Hadrian's Wall-producing 17 known (including Carriden) and several suspected forts in c. 40/2 Roman miles, 2 as opposed to 16 in 80 Roman miles on the southern Wall. Moreover, many Antonine Wall forts were too small to have held a full auxiliary unit and there seemed to be no sign of a fortlet and turret system. Today, however, there is general, if qualified, acceptance of Gillam's hypothesis 3 that the Wall was initially designed as a copy of the secondary, Wall fort, phase of Hadrian's Wall. The theory suggests that the system was originally held by just the six largest forts, a group ranging from c. 3.5 to 6.5 acres and taking in Carriden, Mumrills, Castlecary, Balmuildy, Old Kilpatrick, and one other. The remaining forts would belong to a secondary phase; some may have been planned by the time the Wall was under construction. Gillam extrapolated from the small number of minor sites then known to suggest that a milefortlet, and even a turret, system might one day come to light. The discovery of additional fortlets and the fact that the newly discovered fort at Inveravon 1

Fords and the frontier: waging counter-mobility on Hadrian's Wall

“…Between the milecastles were pairs of turrets, resulting in manned posts every 495m or so along the Wall (Figure 3; Breeze & Dobson 2000: 33–41). Although some flexibility was permitted, the greatest recorded discrepancy between a measured hypothetical mile separating two adjacent milecastles and the actual distance is 213m (Woolliscroft 1989: 7); such rigidity of planning seemingly precluded meaningful flexibility to adapt the frontier to specific local conditions. The simplest explanation for this design is that it was judged to provide the optimal distance between military posts to detect incursions by groups small enough to be deterred or destroyed by milecastle and turret garrisons (Symonds 2010: 12; Foglia 2014: 37–38).…”

Signalling and the design of the Gask Ridge system

“…It must always be remembered, therefore, that the fact that a signalling system was apparently both possible and desirable on a given Roman deployment does not necessarily mean that any such system actually existed. That said, there are design oddities on a number of Roman frontiers that seem to make sense only as moves to accommodate signalling (Woolliscroft 1989a;Woolliscroft & Hoffmann 1991) so that some signals provision does appear likely on many, if not all, of Rome's major military systems.…”

“…Likewise, all the known towers between Glenbank and Kaims also have direct views of Ardoch, as should the three additional towers that might be expected, on spacing grounds, between Glenbank and Ardoch: around Balhaldie (NN 823064),^ Kingfisher Hotel (NN 834080) and Kierallan Farm (NN 837089). In other words, the area is set up to allow the sort of direct signalling system already found on Hadrian's Wall (Woolliscroft 1989a) and the northern part of the Wetterau Limes (Woolliscroft & Hoffmann 1991, 535-6) in which each minor installation has a direct link to a fort rather than signalling laterally from tower to tower along the line.…”