- Fortifications and Defence -
There can be little doubt that the most extensive of the hill-fort defences were
highly consumptive of resources. For example, the principal wall at Mont Beuvray,
Burgundy, encloses 135 ha and is some 5.5 km long. If, like the excavated portion, it
were entirely built in murus gallicus style, up to 100 tonnes of iron spikes and the
product of the clear-felling of 40-60 ha of mature oak woodland would have been
required to build it. The external wall-face, at a minimal height of 4.5 m, would have
needed approximately 7,500 cubic metres of facing stone (some of which was
imported to the site). The core of the wall may have required over 100,000 cubic
metres of fill materials. The organizational requirements underpinning such an under-
taking are manifest. None the less, there is no simple correlation between the
existence of technically elaborate fortifications of this kind and the topmost sites in
apparent settlement hierarchies; in Berry, France (broadly corresponding to the
civitas of the Bituriges cubi in the first century Be), for example, muri gallici occur on
small as well as more extensive sites. Many smaller fortifications were of course much
less resource- and labour-demanding: Hogg's calculations (1975) for some north
British examples suggest the task could have been achieved by small communities of
the size that seemingly inhabited them (perhaps fifty strong) in a few months.
Celtic fortifications may be considered to have faced military threats of two kinds:
that offered by other, relatively local, communities and, more particularly latterly,
against the assaults mounted by the armies of late Republican and Imperial Rome. In
the former case, amongst the weaponry employed, swords, spears and javelins (see
Ritchie and Ritchie, Chapter 4) seem to predominate as assault weapons over much
less plentiful evidence for archery and the use of the sling in the archaeological record
of the La Tene period. Caution has to be exercised, however, since weaponry that
has been recovered most frequently comes from burial or ritual contexts. Fire was
clearly also used (although the wholesale vitrification of some forts is very unlikely to
have been achieved in the heat of battle). Classical written sources - which have
unsurprisingly little to say about Celtic assault tactics - record simple, if effective,
methods, like the massed throwing of stones all around the perimeter, as in the attack
on Bibrax of the Remi, again described by Caesar (De Bello Gallico 11.6; Rivet 1971).
Gates were clearly weak points (Avery 1986), although indubitable evidence of their
destruction during conflict is relatively rare. There are no indications that iron age
warfare was at all mechanized.
The advent of Roman armies, as well as pitting Celtic troops against organization-
ally superior forces, seems to have represented a new departure in terms of the
technologies and styles of warfare in temperate Europe. Artillery pieces, such as the
ballista, were employed. Written sources make reference to the use of other techniques,
such as sapping and battering-rams, although it is not precluded that these latter may
have been in use earlier. The panoply of siege warfare, including investing works, as
most celebratedly around Mandubian Alesia in Cote d'Or, France, equally seems to
have been a product of Roman intervention (Le Gall 1985). Interestingly, whilst Caesar
makes direct reference to the capacity of the murus gallicus -a wall built in a variant of
a long-established style - to resist assault by the battering-ram and by fire in the passage
referred to previously, it was the newer style of massive bank, fronted by its broad,
canal-like ditch, at Noviodunum of the Suessiones (most likely to have been the fort at
Pommiers, Aisne, France) which actually frustrated his assault (De Bello Gallico 11.12).
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