Military Architecture in England During the Middle Ages

by A. Hamilton Thompson

Old Sarum
(From Mr Hadrian Allcroft’s Earthwork of England by kind permission of Messrs Macmillan & Co.)

The steepness of the bank itself constituted a formidable means of defence. At Maiden Castle the great northern banks rise to a height of 60 feet or more. The top of the outer bank of Old Sarum ([4]) is 106 feet above the level of the ditch below.[2] In many cases, and probably in all, the inner bank was crowned by a stockade, consisting of a series of upright stakes, between and round which was twined an impenetrable hedge of thorns. The plateau or berm which was sometimes left behind the parapet of the bank, where there was more than a single bank and ditch, was a valuable asset to the defenders of prehistoric strongholds, forming an advance post from which they were able to wield their missiles freely; while sometimes the summit of one or more of the outer banks was made for the same purpose into a broad platform, which allowed greater freedom of movement. The parapet or counterscarp of the outer ditch was probably defended by a stockade, and it is known that in some cases sharpened stakes or stones were fixed firmly in the bottom of the ditches.

Bury Ditches

The impregnable character of the enceinte was thus ensured. But further skill was necessary to defend the entrances of the camp. Of these there was usually more than one, and these were necessarily formed by cuttings through the banks. As in the case of Maiden Castle, the path of entry could be converted into a labyrinth by multiplying the banks and ditches. Every inch of this circuitous path is guarded by tall ramparts: there are seven or eight points in its course at which fatal error was possible, and one at any rate where an attacking army could hardly fail to rush securely upon destruction. The eastern entrance is so guarded by transverse banks that the path is almost equally difficult to find. It was seldom, however, that entrances were so elaborately protected. At Old Sarum the western entrance is covered by a semicircular outwork, on the flanks of which are the two inlets to the passage through the outer vallum. On the east side the entrance is through a narrow passage which runs for some distance between the parapet of the outer ditch and an outwork, and is at right angles to the actual passage through the bank. The most common method of defending the entrance was to make a diagonal path, usually from right to left, through the banks. Each bank would thus overlap the next: the summits above the path would be broadened out into platforms, capable of occupation by bodies of defenders; and the right flank of the enemy, unprotected by shields, would be exposed to their missiles. The entrance, however, might be substantially protected by giving an inward curve to the inner bank on each side of the path; and this is a plan very frequently employed.[3] Where outworks were specially constructed, their form differs considerably: we have seen them employed in two ways at Old Sarum—as a kind of horn-work thrown out in front of a passage, and as a spur projecting at right angles in front of an entrance. In both cases an absolutely straight approach is precluded. Occasionally, where an approximately direct approach was permitted, it is guarded on one side by a spur thrown out at right angles to the bank. At Blackbury castle, an early earthwork in south Devon, the main entrance has a straight approach guarded on either side by a triangular outwork, which is formed by a most ingenious arrangement of banks and by prolongations of the main ditch ([7]). At the actual entrance the main bank is curved outwards, with broad platforms at the top. The hollow interiors of the outworks might serve as guard-houses, or the attacking force could be driven into them from the gateway of the fort, and penned in a position from which escape was impossible. Sometimes hollows were made in the bank or in a projecting outwork near the gateway to serve as guard-houses. On either side of the main entrance, the bank was often slightly raised. At least one instance is known in which the main gate was concealed by making a break in another part of the rampart, and raising the bank on either side. The enemy, making for this point, would miss the real entrance, and run the risk of losing his life in a cul-de-sac purposely constructed within the rampart.

Blackbury Castle
(From Mr Hadrian Allcroft’s Earthwork of England by kind permission of Messrs Macmillan & Co.)

In these fortresses, the defences of which were due to instinctive skill in the face of constant danger, it is impossible not to recognise how many of the most scientific features of medieval fortification were anticipated. The concentric plan of Caerphilly castle ([270]), with its easy provisions of egress, and its difficulty of access; the spurs which guard the approaches to Beaumaris ([277]) and Conway castles; the barbicans which form so prominent a defence of Alnwick castle ([243]), and the gateways of York have prototypes, of which their engineers were probably unconscious, in the huge earthworks of prehistoric Britain. Through a long interval, in which military art pursued a very gradual evolution, the wheel came full circle. The devices of the earthwork builders were translated into stone with far greater economy of labour.

Although the most conspicuous examples of early earthwork are found in hill fortresses, camps were not confined to hilly sites, nor were their defences always composed of earthwork. There are districts where the hard nature of the soil forbade the construction of earthen banks and fosses; and consequently there are many camps which are surrounded by walls of rough uncemented stone, originally kept in place by facings and bondings of larger and smoother stones.[4] These camps are usually not large. They occur very commonly in the north of England: a good example is that known as the Castles, in the valley of the Bedburn, seven or eight miles west of Bishop Auckland. The enclosure, situated on a boggy slope, is surrounded by shapeless masses of débris, the ruins of the dry-built ring wall, which has lost its facing and so has fallen to pieces. Stone was also used in the ramparts of some of the camps on the rocky hills of Somerset, as in the camps on either side of the Avon at Clifton. The great fortress of Worlebury, above Weston-super-Mare, was surrounded by an immense wall of uncemented stone, brought to great thickness by building several walls, each with its own set of facing stones, up against each other. On its eastern front, separated from the main rampart by a deep ditch, cut in the solid rock, was another wall of stone; and this again was protected by a series of outer earthworks ([9]). Dolebury, at the western extremity of the Mendips, is surrounded by a double wall of loose limestone.[5] In these cases, as in the Welsh strongholds of Penmaenmawr and Tre’r Ceiri, geological conditions made the earthen bank an impossibility, and the stone of the neighbourhood took its place.