The Triple Dyke: part of the Iron Age territorial oppidum and Romano-British town of Camulodunum


Heritage Category: Scheduled Monument

List Entry Number: 1019993

Date first listed: 09-Oct-1981

Date of most recent amendment: 24-Apr-2002


Ordnance survey map of The Triple Dyke: part of the Iron Age territorial oppidum and Romano-British town of Camulodunum
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The building or site itself may lie within the boundary of more than one authority.

County: Essex

District: Colchester (District Authority)

National Grid Reference: TL 96514 24617


Legacy Record - This information may be included in the List Entry Details.

Reasons for Designation

The Latin term `oppidum' usually refers to a town, although in the context of the Roman invasions of Britain, its use in the writings of Julius Caesar and Suetonius encompassed a wider range of fortified settlements and native strongholds. In archaeological terminology `territorial oppida' is used to describe a settlement phenomenon of the later Iron Age - areas of farmsteads, field systems and nucleated settlements of various kinds covering wide areas bounded by substantial earthworks. Such sites are considered to have been tribal capitals or focal places for communities between the 1st century BC and the 1st century AD, serving as centres of trade, manufacture and social prominence. Only a handful of sites in England have been identified under this term (principally Colchester, Bagendon, Silchester, St Albans, Chichester, Grims Ditch and Stanwick), all of which lie in southern, central and western parts of the country. They all share the common characteristic of boundaries defined by massive linear banks and ditches, sometimes intermittent and positioned to include natural barriers such as rivers and marshes. The enclosed areas vary from between 30 sq km and 90 sq km, some marked out by curvilinear boundaries, others by more rectilinear patterns. Activities within the enclosed areas may vary considerably and, given that Iron Age society in southern England was not homogeneous, there is no reason to suppose that all territorial oppida exhibited the same status or served identical purposes. In addition to farmsteads, areas of nucleated settlement and related field systems, other known features of the enclosures include storage pits and wells, areas set aside for burials (sometimes extremely elaborate), temple complexes and areas of pottery manufacture, metal working and the minting of coins. Some, particularly those positioned in coastal or estuarine locations, provide evidence of widespread trade in the form of imported goods, notably Gallo-Belgic pottery, from the continental mainland and the western Roman Empire. Territorial oppida reflect the development of complex social organisation and increased permanence of settlement in the late Iron Age. They also provide some of the most valuable evidence for the impact of Roman conquest and government on native society. Given the rarity of this settlement form and its importance for our understanding of the period, all territorial oppida are viewed as being of national, if not international importance, and all surviving elements are considered worthy of protection.

The territorial oppidum surrounding Colchester (`Camulodunum' in antiquity) encompassed an area of about 25 sq km mainly located between the converging courses of the River Colne and the Roman River to the west of the Colne estuary. In addition to the rivers the settlement was defined and protected by the largest group of linear earthworks of the time in Britain. These developed over a period of about one hundred years from the foundation of the settlement in the early first century BC and mostly take the form of large V-shaped ditches with banks constructed from upcast on the sides facing the settled area. The dykes may have been made still more formidable by the addition of timber palisades and gateways, and they have been interpreted as an expression of the settlement's status, as a means to control and protect grazing stock and as an effective defence against chariots - one of the principal features of later Iron Age warfare. If placed end to end the dykes would extend over a total distance of about 25km. Some 6km now survive as extant earthworks, and many other sections are known to survive as buried features.

The interior of the oppidum is thought to have been largely agricultural - a mixture of enclosed fields, pasture and woodland - with small occupation sites scattered throughout and two particularly large and complex areas of activity located to the west and to the north. At Gosbecks, to the west, an extensive farmstead has been identified. This has been associated with Cunobelin (one of the most famous British kings prior to the Roman Conquest) and interpreted as a centre of political authority and religious practice. Further north, at Sheepen, excavations in the 1930s and 1970 revealed widespread evidence of industrial processes, the minting of coins and continental trade. Associated with the settlement sites are burial grounds, the most prominent of which are the Lexden Tumulus, Lexden Mount, a group of excavated burial enclosures at Stanway (beyond the western dykes), and a similar (unexcavated) enclosure at Gosbecks. These sites reflect the beliefs and complex burial rituals afforded to the society's elite; a large number of less elaborate burials have been discovered across the oppidum.

The rulers and occupants may have fluctuated according to the relative fortunes of two rival tribal polities - the Trinovantes centred on modern Essex and the Catuvellauni based in modern Hertfordshire. An alternative suggestion is that the oppidum served as a Catuvellaunian colony within Trinovantian territory, maintained through political agreements or the warlike ascendancy of the former in order to provide this otherwise landlocked tribe with access to coastal trade. In either case, the oppidum was clearly of central importance to the region in AD 43 when it formed the primary military objective for the invading Roman army. After the collapse of local resistance the Emperor Claudius personally led his victorious forces into the oppidum - which was subsequently reorganised to provide a centre of provincial government and bridgehead for the further conquest of Britain. A small Roman fort was constructed within the Gosbecks complex, and a larger legionary fortress was established on the hill to the east (now the centre of modern Colchester). As the focus of military activity shifted towards the north and west of Britain the fortress was redesignated as a `colonia', a chartered town for a colony of retired soldiers. `Colonia Victricensis' (City of Victory) was the first Roman town established in Britain and thus the earliest truly urban settlement in the country. The burgeoning town was destroyed in AD 60-61 - the first major casualty of the tribal revolt led by Boudicca, queen of the Iceni. In the aftermath of the revolt, the town was rebuilt with a protective wall (based on the perimeter of the earlier fortress), and with the return of order the colonia developed in a manner apparently calculated to integrate the old and new social orders. Native settlement and burial practices continued within the territorial oppidum (now probably a `civitas' or self governing town) which was protected with additional dykes. A temple and a theatre were constructed at the Gosbecks site, and the Sheepen industrial zone was maintained, enlarged and extended to include a further religious complex.

The collapse of Roman government in the early fifth century signalled the end of Colonia Victricensis. Medieval Colchester emerged within the walls of the former Roman town leaving the greater part of the extended settlement and oppidum to disappear beneath its rural hinterland. As a consequence the archaeological remains in this area are remarkable for the lack of later disturbance and present a unique opportunity for the study of the Iron Age and Roman past.

The Triple Dyke is one of the best surviving examples amongst the linear earthworks which defined the perimeter of the Iron Age and Roman settlement. The banks will contain valuable archaeological evidence for the date and manner of their construction, and the buried ditches will similarly contain valuable evidence for the date when this section was built and the period over which it was maintained. The buried silts within the ditches may contain environmental evidence illustrating the appearance of the landscape in which the dyke was set, and the buried landsurface beneath the banks may retain sealed evidence of earlier occupation in the area.

The Triple Dyke, together with its continuation to the south (Shrub End Dyke), is thought to be a Roman construction. The majority of dykes within the system which surrounded Camulodunum were designed to defend the late Iron Age oppidum and its Romano-British successor. The Triple Dyke, however, appears to be a unique variation - built specifically to consolidate the position of the invading forces at an early stage in the Claudian invasion. As such it provides a valuable insight into the military campaign aimed at the conquest of Camulodunum.


Legacy Record - This information may be included in the List Entry Details.


The monument includes the visible and buried remains of a section of late Iron Age or early Romano-British boundary earthwork, known as the Triple Dyke, located along the eastern side of Straight Road some 3km west of Colchester town centre.

The section of dyke follows a NNE-SSW alignment (perpetuated by Straight Road) and extends over a distance of 256m between Chaucer Way and Heath Road. It was constructed as a series of three parallel banks, each approximately 10m in width. These have been considerably reduced since the time of construction and now measure no greater than 1m in height. The banks are separated by ditches and a further ditch flanks the western side of the western bank. The ditches are largely infilled, although they can still be detected as slight intermittent depressions. This section of the Triple Dyke was taken into the care of the Secretary of State in 1925. It is now the only part of this type of dyke to remain visible on the ground, and is the only section included in the scheduling.

The dyke is known to have formerly extended to the north for at least 1.2km, the alignment having been determined from trial excavations and a series of aerial photographs taken in the 1930s. The course of the dyke immediately to the north of the visible section is now overlain by housing. Continuing northwards, the line is believed to have been interrupted by an entranceway broadly corresponding to the current position of London Road, before continuing towards the River Colne at Seven Arches Farm; this northern extension of the Triple Dyke is not included in the scheduling. In 1961 excavations to the north of London Road in Hunter's Rough (now a housing estate) found the ditches to be, on average, 6m in width and 2m deep. A pattern of hobnails, representing a single boot or sandal, was found in the lower fill of the central ditch.

The Triple Dyke is thought to have terminated to the south near the Heath Road junction, although a single ditch and bank, possibly the continuation of the eastern rampart, has been identified over a further 600m (continuing to Dugard Avenue) through a number of minor excavations. This single dyke (known as the Shrub End Dyke) is now almost completely overlain by housing and is not included in the scheduling.

There is currently no definitive evidence for the date of the Triple Dyke, although its linearity and design is thought to indicate Roman rather than Iron Age construction. It has been suggested that the Triple Dyke and Shrub End Dyke were built soon after the invasion of AD 43 to secure a line between the River Colne and existing dyke to the south of Dugard Avenue (Kidman's Dyke) and thereby protect the western side of a temporary military encampment located around the freshwater springs at Lexden. The disparity of design between the Triple Dyke and Shrub End Dyke to the south is not fully understood. The process of triplification may have been left unfinished when the army relocated to the legionary fortress (now beneath Colchester town centre), or perhaps the length of Triple Dyke simply reflected the maximum extent of the temporary encampment.

All fences, fence posts and notice boards are excluded from the scheduling, although the ground beneath these features is included.

MAP EXTRACT The site of the monument is shown on the attached map extract.


The contents of this record have been generated from a legacy data system.

Legacy System number: 29460

Legacy System: RSM


Books and journals
Hawkes, C F C, Crummy, P, 'Colchester Archaeological Reports' in Camulodunum II, (1995)
Hawkes, C F C, Crummy, P, 'Colchester Archaeological Reports' in Camulodunum II, (1995), 174-77
Deed of Guardianship (File AA 40545), Lexden Straight Road, (1923)
Radford, D and Gascoigne, A, The Colchester Iron Age Dykes: Archaeological summary, 1997, Colchester Museums Internal Report

End of official listing