Monument record MDO5932 - Bokerley Dyke, Cranborne and Pentridge

Bokerley Dyke is a linear earthwork around 5.75 km long and is one of the most substantial and visible of all the monuments on and in the vicinity of Martin Down. It has been the subject of part excavations and detailed survey by the Royal Commission on the Historical Monuments of England. These investigations have provided much information on the nature and development of the earthwork. Bokerley Dyke is thought to have originated in the Bronze Age or Early Iron Age and was an important political and cultural boundary which divided areas showing markedly different patterns of land division. Once established, the dyke continued in use but was remodelled and adapted to suit the needs of the later periods. These included the more defensive requirements of the later Iron Age and Roman periods and it was possibly then that the dyke became the focus of the associated series of earthworks making up the `Bokerley Line'. The dyke continued in use after the cessation of the Roman administration and still forms part of a boundary, that between the counties of Dorset and Hampshire.

A defensive work in three parts: 'A' Dyke, 'B' Dyke (Rear Dyke) and 'C' Dyke (Fore Dyke). Excavated by Pitt-Rivers at two points. 'The Epaulement' (SU 0376 1966) and 'Bokerly Junction' (SU 0321 1989). From coin and pottery evidence, 'A' Dyke probably dates to cAD325-30.
'B' Dyke is later (it overlaps and recuts 'A' Dyke at the 'Epaulement') probably dating to shortly after AD 364 (coin of Valens). 'C' Dyke is later still as it is cut into 'B' Dyke at their junction and probably dates to after AD 393-5 (coin of Honorius).

'A' Dyke was probably a territorial boundary (the northern demarcation of an Imperial reserve ?). 'B' Dyke, a strong and definitely military work, was evidently constructed in time of crisis, as it cuts through the Badbury-Old Sarum Road and also ignores an existing, though declining, Romano-British Settlement (SU 031 200), leaving most of it on the undefended side, in its anxiety to use the ground to best advantage; and as the road was restored over it very soon afterwards, the crisis can be assumed to be a short-lived one, almost certainly that of AD 367-8 when the whole of Britain was under attack by the combined Picts, Scots and Saxons. 'C' Dyke seems to represent a last Romano-British defensive line before the final debacle; the Roman road was again cut by it, and this time remained cut.

The name of the works should properly be 'Bokerley Ditch'. (See Strip Map and diagrams). <2>

For field investigation report, see annotations on Strip Map. <4>

The final stage of Bokerley Ditch is more likely to be a boundary work than defensive; probably of 5th century date and demarcating a stage of agreement between invaders and Britains. <5>

Published 1:2500 survey revised between SU 0300-1999 and the eastern termination. This part is striking in its proportions (some 25m in width overall, with the bank rising in places to 4m above the bottom of the ditch). The work has a very close resemblance to the presumed Dark Ages `Grims Ditches' of Mongeham (Oxon) and Pinner (Herts) etc. <6>

Bokerley Dyke (016200-063168), a boundary bank and ditch, often of massive defensive proportions, was built in the late Roman period to serve as a protective barrier or frontier (map opposite). Facing north east, it extends for nearly four miles across Cranborne Chase from a point near West Woodyates in the west to Martin Wood in the south east. For much of its length the dyke is well preserved, though thickly overgrown in places, but north west of Bokerley Juncton, where the modern road following the line of the Roman road from Old Sarum to Dorchester passes through it, the dyke has been badly damaged or levelled by ploughing. To the south east of the junction the dyke constitutes the boundary between Dorset and Hampshire. Excavations by General Pitt-Rivers in the vicinity of the junction are the chief source of information concerning the structural sequence and date of the earthwork (Pitt- Rivers, Excavations III, 3-239). His report has been the subject of reinterpretation by C F C Hawkes (Arch. J. CIV (1947), 62-78).

Further excavations on the dyke were carried out by P A Rahtz in 1958, in advance of road widening (Arch. J., CXVIII (1961), 65-99).

Bokerley Dyke lies across a tract of open Chalk country, furrowed by dry valleys, between the upper reaches of the River Allen and those of the River Crane. At either end it terminates where later deposits (Clay-with-flints in the north west and Reading Beds in the south east) overlie the Chalk; these deposits support woodland today and probably gave rise to more extensive tree cover in the past. In Martin Wood the dyke is of modest dimensions, measuring less than 50 ft. across overall, but it increases steadily in size as it proceeds along the shoulder of the narrow ridge leading to Blagdon Hill, from which it commands a view over the lower ground to the east. On Blagdon Hill the dyke crosses one of the branches of the Grim's Ditch complex (17) and then turns to descend the northern slope of the hill obliquely (Plate 56). Here it reaches its maximum dimensions, 100 ft. across overall, with the bank 8 ft. high and the ditch up to 9 ft. deep. It then continues for over 1 1/2 miles across a relatively low, broad pass or saddle to Bokerley Junction, where the Roman road from Old Sarum to Dorchester and the modern road (A 354) pass through it. Another branch of the Grim's Ditch complex meets it from the north on Martin Down. Some 600 yards east south east of Bokerley Junction a short stub of bank and ditch of comparable dimensions to the dyke itself and known since Pitt-River's day as the Epaulement, extends west from the dyke and marks an earlier termination; the west part of this stub has been levelled.

West of Bokerley Junction the precise course of the dyke is less certain than to the east because of ploughing and earlier levelling. Pitt-Rivers showed by excavation that it bifurcated at Bokerley Junction and he traced the two arms westward on a roughly parallel course. The more northerly of these, which he termed the Fore Dyke, extends to a point 400 yards west of Hill Copse (01562000) and is still clearly visable on the ground for much of its length, though it diminishes in size westward. The southern arm or Rear Dyke, which Pitt-Rivers believed came to an end just north of West Woodyates Manor (01491961), is now almost entirely obliterated. There is no surface evidence to support Pitt-Rivers's belief, and air photographs (V 58 RAF 3250: 0126; C.U.A.P., RC 8 X99) show clearly that it ended 140 yards east of Hill Copse (02221986). A length of bank and ditch extends south west from the Fore Dyke in Hill Copse and appears to join a feature which Pitt-Rivers regarded as part of the Rear Dyke, just north east of West Woodyates Manor.

In his analysis of the date and structure sequence of the dyke (based largely on Pitt-Rivers's observations) Hawkes concluded that it was built from its south eastern end as far as the Epaulement in circa AD 325; that it was extended sometime after 364 (perhaps during the crises of 367-8) to block the Roman road and to continue as the Rear Dyke; that the road was soon unblocked, and that finally, sometime after 393, the Fore Dyke was built and the road was then permanently blocked. As a result of more recent work Rahtz suggests that the dyke extended initially as far north west as the Roman road, leaving an entrance or gap beside the Epaulement, and that this was blocked later, either when the Rear Dyke was built or perhaps permanently only when the Fore Dyke was built. The evidence at present available is insufficient for definitive interpretation.

The course and dimensions of Bokerley Dyke leave little doubt that it was built as defensive barrier or frontier, especially in its final form. It blocks a stretch of open downland which constituted a vulnerable gap between what probably were areas of extensive woodland, a gap through which passed the Roman road from the north east. The dyke was surely designed to prevent penetration from that quarter. Ultimately it may have served to protect the Romano-Britains of east Dorset from the unwelcome attentions of Anglo-Saxon settlers, whose early presence barely 10 miles away in the Avon valley around Salisbury is well attested. It seems likely, too, that Bokerley Dyke echoes or replaces, on a line better sited tactically, an older non-defensive boundary represented by part of the Grim's Ditch complex. To the north west of the Epaulement it is possible that it overlies and follows a branch of Grim's Ditch; on Martin Down a further branch of Grim's Ditch mets, but does not run under the dyke. <7>

SU 0124 1990 [left flank] to 0625 1698 [right flank] The name Bokerley Dyke or Bokerley Ditch appears first in the medieval period (Bockedic 1280). The earliest 10th century reference is merely to 'dich'. The name 'Bokerley' appears to be descriptive and to relate quite specifically to deer (?'Buck' and 'Wood clearing') and so plausibly to the 'chase' and the 13th or early 14th century Blagden deer park, which at that time was bounded at the north east by Bokerley Dyke.

The Dyke as defined by RCHME is an earthwork bank and ditch of considerably larger dimensions than those which constitute the normal run of Wessex boundary ditches. The whole line was probably refurbished at some late stage, making a feature over 5.2km long whose final unitary nature was confused by the incorporation or nearby survival of many diverse strands, some certainly prehistoric, some slight, some only postulated because of the placing of other features, probably embodied in or destroyed by the later Dyke, and others running roughly parallel.

RCHME divided Bokerley Dyke into 8 components and 5 sectors. The components are; Left Flank, Fore Dyke, Rear Dyke, Left Centre, Epaulement, Traverse, Right Centre, Right Flank. Alterations, modifications, levelling and even total destruction of certain areas have taken place in the use life of the Dyke. The chronology of Bokerley Dyke is not certain. Excavations have revealed 4th century coins and pottery as well as earlier samian, but the context of the discoveries and the quality of the excavations are in doubt.

The Bokerley Line was stabilised as a political frontier, indicated by differences in land allotment patterns sometime in the Bronze or Early Iron Age. Linears marking the limits of a particular type of land allotment were built on the Bokerley Line in unknown sequence and detail. A Roman road passed through an entrance in the linear. A massively deep ditch, the Rear Dyke was dug in a discrete length and apparently unfinished. Not long afterwards the ditch was filled in sufficiently to take a rebuilt road. The Dyke may be thought at this time to deter hostile movement into what is today the county of Dorset. This failed because the Dyke was subsequently slighted. The Fore Dyke is different in character from the Rear Dyke, both by reason of its lesser size and by its continuous extent and is possibly post Roman. Perhaps then, on the basis of inevitably slight evidence, Bokerley Dyke in its final form can be conceived as a single frontier work of post-Roman date, placed where it was very largely because it followed a major boundary line established in prehistory but plausibly ending against areas of thick scrub which, at the north end, would have regenerated in former arable. However, there is no convincing argument to exactly what Bokerley Dyke was protecting. <8>

<1> Ordnance Survey, Ordnance Survey Map 6in, 1902 (Map). SWX1540.

(SU 0119 - 0616). Bokerly Dyke (OE)

<2> Royal Archaeological Institute, 1947, The Archaeological Journal 104, 62-78 (Serial). SDO18401.

<3> Rumens, Eric John, Ordnance Survey Field Investigator's Comments EJR, F1 EJR 17/06/1954 (Unpublished document). SDO20445.

<4> Dorset Natural History and Archaeological Society, 1960, Proceedings of the Dorset Natural History and Archaeological Society for 1959, 100-102 (Serial). SDO59.

<5> Frere, S S, 1967, Britannia, 377 (Monograph). SDO19716.

<6> Hastings, Frederick Albert, Ordnance Survey Field Investigator's Comments FAH, F2 FAH 28/06/1969 (Unpublished document). SDO20446.

<7> Royal Commission on Historical Monuments (England), 1975, An Inventory of Historical Monuments in the County of Dorset, Volume V (East), 55-56 (Monograph). SDO129.

<8> Bowen, H C, 1990, The Archaeology of Bokerley Dyke, 15-41 (Monograph). SWX800.

<9> Bowen, H C, 1991, The Archaeology of Bokerley Dyke: Inventory (Monograph). SDO14864.

<10> Historic England, Historic England Archive (Index). SDO14738.

Object Number Object Title Scope And Content
1094015 LINEAR 74 (Bokerley Dyke, SU 0616) (1969) Includes profileAntiquity Model: Revised
1094048 LINEAR 74 (Bokerley dyke, SU 0517) (1969) Includes profilesAntiquity Model: Revised
1094068 LINEAR 74 (Bokerley dyke, SU 0617) (1969) Includes profileAntiquity Model: Revised
1094083 SU 01 NE 4, 8 (Martin 29), 9 (Martin 28), 11 (Martin 26 and 27), 34, 36 (Martin 20), 37, LINEAR 74 (Bokerley dyke, SU 0518) and (Grim's ditch, SU 0518) (1969) Includes profileAntiquity Model: Surveyed
1094123 5, 39, LINEAR 41, LINEAR 74 and LINEAR 498 (Roman road 4c, SU 0319) (1969) Includes profilesAntiquity Model: Surveyed
1094233 SU 01 NW 40, 41 (SU 0419), LINEAR 41 (Dorset cursus, SU 0419), LINEAR 74 (Bokerley dyke, SU 0419) and LINEAR 76 (Grim's ditch, SU 0419) (1969) Antiquity Model: Resurveyed
884555 RCHME: Bokerley Dyke, Pentridge, Dorset 3 detailed drawings of 3 area of dyke
907079 RCHME: Bokerley Dyke, Hampshire Sketch survey. Inscription: Sillen Lane as it crosses dyke
907195 RCHME: "The Archaeology of Bokerley Dyke"
BB76/04851B PROFILES AT WOODYATES AND BLAGDON HILL DRAWN BY HEYWOOD SUMNER Photographer: UNKNOWNDonor: UNKNOWNCopyright: UNKNOWN
ME000991 Ordnance Survey plan SU 0517: Showing archaeological site Linear 74 (Bokerley Dyke) Ordnance Survey plan amended with pencil, ink and sketch sections.
ME001267 Ordnance Survey plan SU 0616: Showing archaeological site linear 74 (Bokerley Dyke), with a sketch section The object consists of two pieces of paper joined with adhesive tape.
ME001268 Ordnance Survey plan SU 0617: Showing archaeological site linear 74 (Bokerley Dyke), with a sketch section The object consists of two pieces of paper joined with adhesive tape.
RCH01/095 The Archaeology of Bokerley Dyke This large archive contains material published in the RCHME volume 'The Archaeology of Bokerley Dyke', but also a significant amount of unpublished archive, particularly for medieval sites.

<11> National Record of the Historic Environment, 906268 (Digital archive). SDO14739.

Record last edited

Oct 25 2024 4:13PM