CONTINENTAL CELTIC FORTIFICATION

Excavation of the fortifications in the western precinct of the oppidum at Staré Hradisko, Czech Republic, in 1990

Introduction

Iron Age fortifications, like those of other periods, are best understood as directly related to a given society’s battle techniques/traditions. This is the common-sense view and was, until recently, the usual archaeological interpretation, since it is clear that innovations in weapons technology have often given rise to basic changes in the development of defensive earthworks. However, experts now increasingly recognize ancient fortifications also as important cultural statements which define group identity and status. Thus, each defensive structure must be viewed in its social and economic context, since it may have served as a demarcation of ethnic, economic, political, social, or territorial boundaries, but might have alternatively or also stood as a marker of power and prestige. Advanced types of composite ramparts, such as the murus gallicus (see below), together with their often imposing gateway constructions, must be viewed as monumental elements of the Celtic hill-fort or oppidum.

The majority of fortifications date from the later Hallstatt period (c. 700–c. 475 bc) and Earlier and Later La Tène (c. 475 bc until Romanization). Continuous settlement at such sites was rare (e.g. Závist in the Czech Republic, see Boii), with a hiatus often occurring during the Middle La Tène period (c. 350–c. 200 bc).

Late Hallstatt and Early La Tène fortifications rarely exceed 30–40 ha (72–100 acres) and are mostly situated on naturally protected high plateaux. Defensive circuits of ramparts on islands and plateaux, as well as promontory sites partially defended by natural features (such as the sea or sheer cliffs), and the more typical hill-forts with single or multiple rings of defences have been discovered.

Rampart Types

Besides simple earthen ‘dump’ ramparts and dry-stone walls, other techniques of defensive construction attested at late prehistoric sites include simple wattleand- daub structures with palisaded walls and wooden box-type constructions, such as that found at Biskupin in Poland. By the Iron Age, more advanced methods of defensive construction had developed. The clay brick construction employed at the Heuneburg with its bastions is unique and does not seem to have been of great influence. It appears to have been an imitation of such techniques in use in the classical world, and will not be dealt with here. The main construction methods employed on Continental and southern British hill-forts and oppida are outlined below:

(1) The Altkönig-Preist type rampart was constructed of vertical wooden posts inserted in a drystone wall. These vertical timbers were exposed in the outer face of the rampart and, less often, in the inner face. The posts were earth-bound or supported on stone slabs positioned about 1–3 m apart. The thickness of the rampart varied between 3.5 m and 6 m. One variation of this method was the use of horizontal wooden beams, arranged lengthwise and crosswise, to link the vertical posts, with the space in between filled with a mixture of stone and soil. This type was prevalent in a region stretching approximately from the northern edge of the Alps in the south to Luxembourg in the north.

(2) The Kelheim-type rampart was a vertical post and stone panel-work arrangement, similar to the Altkönig-Preist type, but much simplified, with only one layer of horizontal beams anchored into the earthen rampart. In this form of rampart the inner face was often ramped gradually down to the ground level of the interior. This construction technique was mostly utilized in the eastern part of the La Téne cultural area.

(3) The Ehrang-type rampart was constructed of horizontal beams arranged lengthwise and crosswise and anchored to a stone wall which formed the defensive exterior, with the ends of the beams running crosswise through the rampart, visible in its outer face. The dry-stone facing of the outer walls was generally only a course or two thick and could not have survived any length of time without the timber-laced backing of earth.

(4) The murus gallicus technique described in Caesar’s De Bello Gallico (‘Gallic War’) is a variant of the latter Ehrang type. In this type, the lengthwise and crosswise beams were fixed together at the point where they passed over one another by using large iron spikes. The bulk of the rampart was filled in with rammed soil and, as with the Kelheim-type rampart, the inner face was often ramped gradually down to the ground level of the interior. This type was first noted by Caesar at the siege of Avaricum in 52 bc and appears to have been popular in western Gaul. In this case, the deep ditch, which often lay immediately outside the rampart, sometimes possessed a near vertical inner edge, which was combined with the outer face of the rampart to form a sheer obstacle several metres high. Modern estimates based on excavated examples suggest that up to 700 man-hours may have been required for the construction of each metre length of such ramparts. Several other variants on timber-laced ramparts composed of stone and earth—such as the Kastenbau type, the Fécamp type and the Basel-Münsterberg type—have also been identified by archaeologists.

Gateways

Besides simple entrance gaps in the walls accompanied by short passageways, several more elaborate gateway layouts are known. The typical gate was the zangentor, the pincer-gate, in which the gate passage narrowed towards the inside. The passageway, which frequently assumed a funnel shape, often had two lanes and was secured by a gatehouse (e.g. Závist, Bohemia, and Manching, Bavaria) or a gate tower (e.g. La Chaussée- Tirancourt, France). Otherwise, towers are rather rare. At their entrance point, gates could be as wide as 15 m (e.g. Bibracte, France; Titelberg, Luxembourg), but there were also very narrow passages with a width of only about 2.5 m (e.g. Kelheim, Bavaria). At several sites the entrance way featured extra walls or ‘hornworks’, which extended outwards from the main defences at a right angle near the gateway, thereby extending the passageway to the entrance considerably and, as a result, the exposure time of attackers to the efforts of the defenders (e.g. Danebury, Dorset).

Further reading

Bibracte; Boii; Caesar; Danebury; Gaul; Hallstatt; Heuneburg; Iron Age; Kelheim; La Tène; Manching; oppidum; Titelberg; Buchsenschutz et al., Les remparts de Bibracte; Collis, Celtic World 159–75; Collis, Defended Sites of the Late La Tène in Central and Western Europe; Collis, Oppida; Dehn, Celticum 3.329–86; Dehn, Germania 38.43–55, 47.165–8; Fichtl, La ville celtique; Furger-Gunti, Jahrbuch der Schweizerischen Gesellschaft für Ur- und Frühgeschichte 63.131–84; Guichard et al., Les processus d’urbanisation à l’Âge du fer; Harding, Hillforts; Leicht, Die Wallanlagen des Oppidums Alkimoennis/Kelheim; Metzler, Das treverische Oppidum auf dem Titelberg; Meylan, Reallexikon der germanischen Altertumskunde 20.388–91; Moor, Spätkeltische Zeit am südlichen Oberrhein 22–8; Motyková et al., Archaeology in Bohemia 1986–1990 115–25; Ralston, Celtic World 59–81; Sievers, Manching; Urban, Der lange Weg zur Geschichte 332–68.