The Archaeology of Britain: An introduction from ... - waughfamily.ca

• 152 • W.S.Hanson
provision of watchtowers, though the system is still known only in embryo, being best attested in
the central sector and at the western end (e.g. Jones 1979).
These dispositions represent the first stages in the creation of a frontier across the Tyne-
Solway isthmus that eventually culminated in the elaborate and extensively studied provisions of
Hadrian’s Wall (Breeze and Dobson 1987) (Figure 8.10). Nonetheless, there is still a good deal to
discover of its earliest development. It is clear that the original Hadrianic plan was merely an
augmentation of the pre-existing frontier along the Stanegate by the construction of a running
barrier of stone or turf. This connected a series of watchtowers (usually now called ‘turrets’) at
intervals of 500 m, with garrisoned gateways every 1.6 km (1 mile) in fortlets, generally now
referred to as ‘milecastles’. Thereafter, the plan underwent continuous modification until its
abandonment when the Romans expanded northwards to reoccupy Scotland in AD 139. The
major change was the construction efforts on the line of the Wall itself, though only some of the
forts to the rear were given up in the process. This was clearly a recognition that the linear barrier
not only served to exclude unwanted incursion from the north, but made it more difficult for the
Romans to deploy troops rapidly beyond it.
Given that the army had just left one linear barrier that was still undergoing modification, it
ought not to be surprising that they should choose to construct another when the readvance into
Scotland at the behest of Emperor Antoninus Pius had been completed. This was set across the
Forth-Clyde isthmus. As originally conceived, the Antonine Wall seems to have been modelled
on Hadrian’s Wall in its developed form, with forts attached to the barrier at intervals of
approximately 13 km and fortlets 1.6 km apart between them (Hanson and Maxwell 1986), although
the absence of a system of watchtowers, the equivalent of the turrets on Hadrian’s Wall, remains
a problem. The Antonine Wall also underwent dramatic modification during its construction,
with the addition of a series of smaller forts reducing the average spacing to some 3.5 km, and
resulting in a denser concentration of forces than on any other linear frontier in the Empire
(Figure 8.10b). Such a dramatic change can only have been in response to some perceived threat,
though there is no direct evidence of it. However, occupation of the more northerly wall was
relatively short-lived. By the 160s AD, the Romans had withdrawn to Hadrian’s Wall, though
details of the fluctuations involved and their precise dates remain in dispute (e.g. Hodgson 1995).
Apart from the brief period of the Severan campaigns, when completion of the conquest of
Scotland was again a possibility (Breeze 1982), Hadrian’s Wall remained the northern frontier of
the Province of Britain, though the distance over which control extended beyond it varies, as is
indicated by the fluctuation in the occupation of outpost forts.
The function of frontiers
Hadrian’s Wall is perhaps the best known frontier in the whole of the Roman Empire, but it is far
from typical of Roman frontiers. Most were not defined by linear barriers, and, among those that
were, the provision of a massive stone wall was not the norm. Even where obvious demarcation
lines were provided, whether manmade or natural, such as rivers, they do not necessarily define
the limit of Roman occupied territory and rarely do they define the full extent of the territory
over which Roman control was exercised. The provision of outpost forts as a regular feature of
both frontier walls in Britain indicates that military occupation normally extended between
approximately 8–40 km to the north of them. Moreover, it is quite clear that, for most of the
third and fourth centuries, patrols exercised Roman military control considerably further afield.
Where no obvious line was demarcated, the definition of the limit of Roman territory can be
even more difficult. Indeed, it remains a matter of debate whether there was ever a precisely
defined legal limit to the Empire, even though this might seem a necessary prerequisite for
administrative purposes.