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previous: Chapter 4 This webpage reproduces a chapter of Romano-British Buildings and Earthworks by John Ward published by Methuen & Co. Ltd. 36 Essex Street W. C., London 1911 The text, and illustrations except as noted, are in the public domain. next: Chapter 6

 p110  Chapter V

THE NORTHERN FRONTIERS

The Walls of Antoninus and Hadrian

Few Roman remains in Europe have attracted more attention than these two lines of northern frontier defence. The lower and older, stretched across the island from the mouth of the Tyne to the Solway; the upper, across the narrower isthmus between the indents of the Forth and the Clyde. The term Wall, however, does not give an adequate idea of these great works. Each was a complex of forts, continuous rampart with towers, military roads, and outlying posts, planned with consummate skill and on an imperial scale; but, in addition, the southern wall has enigmatical features which have long been the subject of controversy. The literature of these barriers is voluminous, extending from Roman times to the present day, and includes some of the most important works on Roman archaeology that have been produced in this country. The widened interest which resulted from the successive editions of the late Dr. Collingwood Bruce's monumental work, The Roman Wall, in 1851, 1853, and 1867, shows no sign of abatement; rather the reverse, to judge from the numerous explorations instituted by northern archaeological societies during the last dozen years.

Both lines appear to owe their inception to the military genius of Agricola. The strategic advantages of the northern isthmus were certainly recognized by him, for he held it by a series of military posts; and it is probable that some of the forts upon or near the Solway-Tyne line are also due to him. His immediate successors lacked his energy, and during the period of border unrest which followed, the Caledonians made at least one serious inroad into the province. To remedy this dangerous  p112 state of affairs, Hadrian appeared upon the scene in A.D. 119; and, in keeping with his general policy of consolidation rather than expansion, he constituted the lower isthmus the chief, if not the only, frontier. To this emperor, then, must be accorded the honour of the initiation of the magnificent barrier which crossed the isthmus, but, as will be seen later, it is uncertain how far the existing structures may be regarded as his.

It is probable that the Agricolan posts of the upper isthmus had already long been abandoned; but twenty-five years after Hadrian's visit, and in consequence of further border trouble, Lollius Urbicus, the legate of Antoninus Pius, fortified that isthmus with a 'wall.' This may have been the outcome of a return to the 'forward' policy of Agricola, in which case we may regard is as simply marking the first halt in a projected conquest of North Britain. On the other hand, it may have simply been intended as an additional security, the barrier serving, as Dr. Haverfield has suggested, as a 'breakwater' to mitigate the pressure of the Caledonians on the frontier proper. Or again, for reasons of policy, the Roman government may have placed the natives of the intervening country under a protectorate, with a view to forming a friendly buffer-state between the province and the Caledonians. Under any circumstance the barrier of the lower isthmus continued to be held, and in fact served as the base whence detachments were drafted to man the upper line.

This duplication of frontiers, however, was of short duration. Dr. Haverfield, in the Antonine Wall Report,​1 shows that history, inscriptions, and coins are alike silent as to "any general occupation of Scotland by Romans later than the reign of Marcus Aurelius"; and the late Mr. Thompson Watkin scarcely hesitated to date the evacuation of the northern wall from the great Caledonian inrush which took place in the first year of Aurelius' successor, Commodus, 180 A.D.​2 Mommsen was in favour of a longer occupation, but this was based upon the supposition that the barrier which Severus strengthened or rebuilt was the Antonine and not the Hadrian, a matter to which we shall revert later. On the other hand, the latter line continued to be the recognized frontier to the end of the Roman era; and in consequence of this, together with its greater length, complexity, and more massive  p113 construction, it has ever attracted the lion's share of attention from students of this branch of Romano-British archaeology.

Various Roman and British writers, as Dio Cassius, Aelius Spartianus, Eutropius, Aurelius Victor, Orosius, Cassiodorus, Gildas, Nennius, and Bede, have referred to or have described these great frontier defences, but to give even an outline of their testimony would demand too much space. The statements of these writers are, as a rule, vague and confusing, evidently written from hearsay, and sometimes quite unintelligible; still, when carefully studied in conjunction with the archaeological evidence, and especially with the inscriptions, they supply much valuable information.

The Antonine Wall

This 'wall' stretches from Old Kilpatric on the Clyde to Bridgeness, near Corriden, on the Forth, and the length of its gently sinuous course is about 36½ miles. For most of this distance its rampart and ditch are still visible; the former showing, where best preserved, as a broad and shallow convex mound, and the latter, as a more pronounced indent at a varying distance in front, that is, to the north. Less conspicuous is an irregular mound or glacis on the northern side or counterscarp of the ditch; and at a varying distance behind the rampart may be occasionally distinguished the military way. "The work is thus in its entirety a quadruple line, which, instinct with Roman greatness of design and thoroughness of execution, undulates across the isthmus with a course as direct as the strategic requirements of strength would admit. It skilfully takes advantage of high ground, commanding, throughout almost its entire course, a valley or low-lying ground in front. Occasionally it passes over ridges of a considerable elevation above the sea-level, as at Castlehill, Bar Hill, Croy Hill, and Westerwood. The three points last named stand close on the watershed of the isthmus — the Kelvin flowing westward, and the Bonny eastward, almost from their base. To the east of Westerwood the line of the vallum never reaches a height of 250 ft., but occupies a line of great natural strength, with the carses of the Forth lying in front of and at a considerable depth beneath it, until close on the terminal point at Bridgeness, where it sinks rapidly, to  p114 end itself on the shores of the Forth."​3 Add to this 'quadruple line' the remains of a dozen or more stations for the accommodation of the garrison and the traces of 'periodic expansions' at the rear of the rampart, and the reader will have a general idea of the Antonine Wall. Each member will now be described in detail.

The Rampart or Wall.— This work was regarded by the older antiquaries as made of the upcast of the ditch; but the investigations of the Glasgow Archaeological Society, between the years 1890 and 1893, conclusively showed that the anterior mound or glacis alone accounts for all of it. The rampart was proved to be not ordinary earthwork at all. It is characterized throughout by the presence of thin dark seams dividing the earth into a series of courses. "The dark horizon lines, in spite of numerous breaks and forks and blendings, preserve a remarkable parallelism. . . . At places they are so thick as to challenge comparison with the thickness of the intervening layer of other soil. At other places they are as often under as over half an inch in thickness. . . . The shades of colour vary considerably also: at some points they are black and bold, at others they are not black, but merely dark; at others, again, they are so faint and thin as to be hard to detect. Striking an average over the whole of the sections, it may be said that the distance between these strange lines is usually about three inches, and their general colour a mossy brown. But wider or closer, darker or lighter, thicker or thinner, there the lines are, not in one section, but in all."​4 The darkness of these lines is due to vegetable matter; and the conclusion which the excavators unhesitatingly arrived at, was, that the rampart was built of sods; in other words was turfwork, not earthwork.

That turf ramparts were frequently raised by the Roman engineers has already been noticed in these pages. That the Antonine rampart was of turf was known to Julius Capitolinus, who, writing about the close of the third century, relates how Antoninus Pius, through his general, Lollius Urbicus, conquered the Britons and built a murus cespiticius. And the Welsh and English chroniclers, Gildas, Nennius, and Bede, tell obscurely of a turf and a stone wall between the Picts and Scots of the north and the civilized population of the south, which may  p115 reasonably be identified with the two barriers considered in this chapter. The discovery of the Glasgow Society, therefore, is an instance of the confirmation of history by archaeology.

The rampart, as it now is, is rarely less than 32 ft. wide, or more than 4½ ft. high. Beneath it, and resting upon the old surface, is a spread of large rough stones, edged on either side with a row or kerb of squared stones, the width over all averaging between 14 and 15 ft. This constituted the foundation of the rampart; and it served also as a 'rumbling drain' to keep it dry, further provision in this respect taking the form of definite culverts here and there through it. This foundation determines the original width of the rampart, the present excess of which represents the spreading out of the turfwork by the combined action of its own weight, the disintegrating effects of the elements, and the operations of agriculture. The rampart appears to have been faced with clay, like those of Camelon, Ardoch, and Coelbren.5

Some interesting estimates of the original proportions of the rampart are given.​6 At Rough Castle, for instance, nineteen turf-courses remain, and it is estimated that the original thickness of the turves was 5 ins. Assuming that a few layers have disappeared, the original height of the rampart, independent of a parapet, would be not much over 10 ft. In another way the height can be gauged. In order to ensure stability, it would be necessary for the structure to have a decided batter, and a slope of 1 in 2½ of rise would be well within the limits of safety. With this slope, a wall 14 ft. at the base, would be reduced to 6 ft. at a height of 10 ft., and this, with a breastwork of wood, would afford sufficient space to comply with the Vitruvian canon that a rampart-walk should be wide enough to allow of two men passing one another.

The Ditch.— In its normal form, that is, where it is cut in the ordinary soil of the district, the ditch is V‑shaped, having a width of about 40 ft., and depth of 12 ft. The chief exception to these dimensions occurs along the foot of Croy Hill, where the masses of rock interfered with its regular formation. Here the sides are much steeper, and the average width is 20 ft. The ditch, it may be remarked, was a dry one, as usual in Roman work.7

 p116  The Berm.— Between the ditch and the rampart is a strip of natural surface, normally from 24 to 30 ft. wide, but sometimes narrower or considerably wider. In its great width, the berm (if it is permissible to apply the term to so wide a space) contrasts with those of the stations, but it is comparable with that of the barrier of the lower isthmus. One suggested explanation for so wide a berm is the position of the rampart and the nature of the soil. The former is almost invariably on ground which slopes to the north, consequently the drainage is in that direction; and this combined with the sandy nature of the upper soil would "tend to render the scarp unstable and make the erection of a high rampart near the edge of the ditch a matter of great risk." Arising from these is a strategic reason. It is contended that "the top of the wall was in line with the angle of the scarp of the fosse, so as to have the bottom of the ditch fully in view and under the fire of the soldiers on the wall without their unduly exposing themselves. Without a berm this would not have been so; the bottom of the ditch would not have been under effective fire from the top of the vallum at all; in other words, the bottom of the ditch would have been what in military language is termed 'dead.' By setting the wall some distance back from the ditch this disadvantage would be obviated, whilst, at the same time, the perfect stability of the structure would be ensured."​8 The theory is ingenious, and it seems to explain in a general way the correlation of the rampart, berm, and ditch; but its weak point is why the forts along its line should have narrow berms, as appears to be the case.

The Glacis.— This outer mound has little in common with the modern glacis except in its position. It consists, as already stated, of the upcast from the ditch; and is very irregular in form. "Yet even in this seeming irregularity there is, roughly speaking, a rule. There are in the main two shapes, the flat and the heaped-up, and the adoption of these respectively appears to a considerable extent to have been governed by the nature of the levels of the ground at the various points."​9 Briefly, where the opposite faces of the ditch are of about the same height, the former type prevails; and where the outer, or northern, is lower than the inner, the latter prevails; but nowhere does the glacis appear to have been so high as to have afforded shelter  p117 to the enemy, or to have interfered with the 'command' of the rampart.

'Periodic Expansions.'— Here and there along the line are projections from the inner or south side of the rampart, which, for want of a better name, are termed 'periodic expansions.' Little is known of them or of their distribution. In their present condition they appear as roughly rounded bulges, which gently slope off, like the rampart itself, to the surrounding level. Two have been cut through on Croy Hill,​10 and both were found to be of turfwork, but of separate construction from the rampart. One of these projects some 38 ft. and is about 60 ft. in width; and the other is somewhatº longer and narrower. These are, of course, their dimensions in their present spread-out conditions; what their original shape and sizes were, can only be conjectured at present. The Croy-Hill examples are 80 ft. apart, but there is no evidence that this represents the normal or even usual distance between the 'expansions' generally. The remains are so slight, as a rule, that it is almost certain that the sites of many are quite unknown, and for this reason it would be idle to speculate whether their periodicity had the approximate regularity of the mile-castles of the lower barrier.

The use of these projecting masses has not been satisfactorily solved. In Gibson's edition of Camden's Britannia they are described as "Watch towers within a call of one another, where Centinels kept watch day and night." The Antonine Wall Report admits the possibility that "they may have formed the basis for wooden turrets used as watch-towers or sentry-boxes"; also that "they may have been 'ramps' or steps to mount the wall from the south side answering to the 'double ascents' of Hyginus." But greater stress is laid upon the theory that they served as the bases or solid platforms for artillery, and in support of this, the finding of stone projectiles along the line of the fortification is cited.11

The Stations.— The garrisons were stationed at intervals along the line in forts or castella, of which the sites of ten are known and those of six or seven more are surmised. The known sites, starting from the east, are Rough Castle, Castlecary, Westerwood, Bar Hill, Auchindavy, Kirkintilloch, Balmuildy, New Kilpatrick, Castlehill, and Duntocher. These are on the actual  p118 line; but a little north of it, near Rough Castle, is the fort at Camelon, which may be regarded as an advanced post. Between the Forth and Rough Castle, 10½ miles, the stations have not been determined, but it is conjectured that they occurred at Bridgeness, the eastern terminus of the Wall, Kinnel, Inveravon, Mumrills, and Bantaskine. It is also conjectured that there was one midway between Kirkintilloch and Balmuildy, at Cadder; and another at Chapelhill at the western end of the Wall. Assuming that these conjectural allocations are correct, the stations were more closely placed than those along the Wall of Hadrian, the shortest interval being about 1¾ miles, and the longest, between Rough Castle and Castlecary, 3¾ miles. With the exception of Castlecary, Rough Castle and the fort on Bar Hill, which have been explored with the good results already described, little is known of these stations, as their visible remains are very obscure. Dressed stones are found about the sites of several, from which we may infer that, like Castlecary, they were stone forts or at all events contained stone buildings. Normally, they were applied, like the mile-castles of the lower isthmus, to the Wall, its rampart forming their northern defence; but one at least, Bar Hill, and probably also Castlehill, were slightly set back from its line.

The Wall of Hadrian

This grand barrier extends from Bowness on the Solway to Wallsend on the Tyne, and is 73½ miles in length, or almost double that of the Antonine line, with which it has points both of resemblance and difference. Like it, it has a similar succession of ditch with glacis-like outer mound, wall set back so as to leave an intervening berm-like space, and military road behind; also, at intervals, fortified stations for the garrisons. But, unlike it, the wall is built of stone; and the stations are in two series, one of greater, and the other of lesser size, which may be distinguished respectively as Forts and Mile-castles. The most striking point of difference, however, is a line of ditch and earth-mounds in the rear of the military road, known as the Vallum. This has no counterpart in the Antonine barrier, and is a most puzzling feature. The lower barrier thus resolves itself into two sets of works: the Wall with its appendages, and the Vallum.

 p120  These two lines pass from sea to sea in close companion­ship as a rule, running parallel some 60 or 80 yds. apart for miles on the stretch, along the more gently undulating lands of the eastern and western thirds of their course. But in the intervening rugged limestone region between Thirlwall and Sewingshields, this parallelism disappears, and the two lines seem at first sight to pursue independent courses, drifting apart here and there to the extent of half a mile or more. Yet it is here more than elsewhere that they bear the impress of a common design and scheme.

These divergencies in the middle third of their course are due to the configuration of the country. The Vallum pursues the more direct course — "a flexible line composed of straight pieces," as Dr. Haverfield aptly expresses it; while the Wall does not hesitate to leave its companion for higher grounds. In this rugged region, where the hills have gentle dip-slopes to the south and craggy precipices to the north, the normal position of the latter is the crest; that of the former, the slope behind. Of the Wall, Dr. Bruce thus wrote: "Shooting over the country, in its onward course, it only swerves from a straight line to take in its route the boldest elevations. . . . But if the murus never moves from a right line, except to occupy the highest points, it never fails to seize them as they occur, no matter how often it is compelled, with this view, to change its direction. It never bends in a curve, but always at an angle. Hence, along the craggy precipices between Sewingshields and Thirlwall, it is obliged to pursue a remarkably zigzag course; for it takes in its range, with the utmost pertinacity, every projecting rock. This mode of proceeding involves another peculiarity. The Wall is compelled to accommodate itself to the depressions of the mountainous region over which it passes. Without flinching, it sinks into the 'gap' or pass, which ever and anon occurs, and, having crossed the narrow valley, ascends as unfalteringly the steep acclivity on the other side."12

Between these great works, the Wall and the Vallum, the military road in the more hilly regions pursues a path which is parallel to neither, but which has been determined with a view to the easiest route from point to point.

The Wall.— As already stated, the Wall was of stone. Where  p121 best preserved it remains to the height of 5 or 6 ft., and in one instance of 8 ft.; but in those districts the land has been long under cultivation, it is more often reduced to a mere ridge of foundation rubble, or has so completely disappeared that only the ditch remains to indicate its line. Where ascertainable, the thickness varies from 6 to 9½ ft. What the original height was, can only be guessed. Sundry writers, from Bede to Camden, name 12 to 21 ft. for well-preserved portions in their times. It is probable that the last is an exaggeration, and that Dr. Bruce's conjecture of from 18 to 19 ft. is not far from the truth.

The Wall was faced front and back with well-squared stones selected with great care. The construction is not uniform. In most places the facing appear to have been built in stages of two or more courses, the intervening rubble being consolidated by grout. Less frequently the Wall was raised course by course, each being topped with a layer of trowel-laid mortar. Bonding tiles, the courses of which are so characteristic of Roman masonry in the south-east of England, are not used, as the abundance of large-sized building stones rendered them unnecessary. "On wavy ground the courses of the wall follow the undulations of the surface, but on steep inclines the stones are laid parallel to the horizon" (Bruce).

The Ditch.— This accompanies the Wall throughout its whole length, except where it would be of little practical use, as along the edges of the cliffs and for •a mile or two west of Carlisle, where the Eden takes its place. "No small amount of labour has been expended on the excavation of the ditch; it has been drawn indifferently through alluvial soil and rocks of sandstone, limestone, and basalt. . . . The fosse never leaves the wall to avoid a mechanical difficulty."​13 Its dimensions vary considerably. In some places it attains a width of 40 ft.; but Hutton's  p122 estimate of the average width as 36 ft., and depth as 15 ft., may be accepted as approximately correct. Wherever it has been examined, it has a flat bottom with sloping sides; and the upcast, like that of the ditch of the Antonine Wall, was used to form a glacis-like mound or spread.

Stations.— Along the actual line or in its vicinity are the remains of the stations which accommodated the garrisons. Of these, about nineteen are known, some still imposing though in ruins, others reduced to the barest traces. Their distances apart range from 2 to 7 miles, but most fall within the limits of 3 and 5. Their plans, so far as they are known or can be inferred, are those of typical Roman forts. Some, including the three or more detached stations, were apparently constructed, not only before the Wall, but before it was contemplated, and were subsequently woven into the mural scheme. The majority, however, were undoubtedly part of the scheme, although not necessarily built at the same time as the other works. It is reasonable to think that the first step would be to secure a safe retreat for the builders, and the easiest way to accomplish this would be to first provide the stations.

So far as we know, they were all 'stone' forts. They differed in size: Drumburgh, the smallest, having an area of ¾ acre; Birdoswald, the largest, •5½ acres. They differed in shape: Wallsend, of which few traces remain, was a square; Great Chesters, a short oblong; Housesteads, an elongated oblong; and Halton, an oblong with a rectangular projection or 'annexe.' They differed in their relation to the Wall. There were the detached forts lying to the south, as Chesterholm and Carvoran; those which simply came up to it, one end or side continuing its line, as Great Chesters, Birdoswald, and Carrawburgh; and those which straddled across it and projected into the space beyond, as Chesters, Rutchester, and Halton. The gates were usually four; but two at least of the larger forts — Chesters and Birdoswald — had six. In those which were on the actual line of the Wall, one of these gates opened into the extra-mural space, the only known exception being Chesters, with three. In their direction the stations fall into two series — those in which the axis or 'length' is parallel to the Wall, as in Great Chesters and Housesteads, and those — the majority — in which it is transverse to it, as in Chesters and Birdoswald. In other  p123 words, the direction of the one series is approximately east and west; that of the other, north and south. So far as we know, the former had their fronts towards the east; the latter, towards the north.

Mile-Castles.— These differed from the stations in several important particulars. They were smaller, more numerous, and distributed at tolerably even distances. The sites of about fifty have been identified, but their remains are for the most part extremely slight, consisting of mere rises in the ground or variations in the herbage; and in a few instances all visible traces have disappeared during the last century. In the wilder middle region, on the other hand, some are still conspicuous, three in particular, one near Housesteads, one at Castle Nick, and one at Cawfields;​14 and these, together with one at Poltross, have been excavated with good results.

These fortlets were all of oblong form, averaging 60 ft. by 70 ft. They were attached to the Wall, and the remaining three sides were of similar thickness and workman­ship, and bonded into it. The free angles were boldly rounded off. In the centre of the north and south sides were gates of single openings, as described on page 65, and through these passed the single street. At Poltross,​15 there was on each side of the street an oblong building, 16 ft. wide and between 50 and 60 ft. long, with four doors, indicating as many rooms. These buildings were separated by a narrow interval from the side walls of the Mile-Castle, but were set back from the Wall, 8 ft., and this interval contained an oven and the steps to the rampart-walk. The excavation of the Housesteads example revealed two floors with an intervening layer of rubbish derived from the partial destruction of the main fabric during a successful inroad of the barbarians. The lower of these had resting upon it much charcoal and other vestiges of a conflagration, derived probably from timber structures built against the walls. Upon the upper floor were the remains of a second series of buildings similarly placed. At Castle Nicks the foundations of similar buildings were found, but independent of the main walls and rudely constructed.

The distribution of the mile-castles is a point of great interest. Maclauchlan's maps show the sites of fifty-two; but these do not  p124 represent the original number. West of Wallhead none are shown, the sites along this portion of the line being uncertain; but eastwards of that point the chain is tolerably complete. Along the less hilly portions of the latter, that is, between Wallsend and Sewingshields, and between Thirlwall Castle and Wallhead, the fortlets recur, as a rule, after intervals of a trifle less than a mile, the exceptional intervals being twice or thrice the length, from which we may reasonably infer the former existence of intervening fortlets. The average length of the shorter intervals (of which there are twenty-six) is 1625.8 yds., or only 7 or 8 yd. in excess of the usual estimate of the Roman mile, the engineers evidently relaxing their rule in order to select the most advantageous positions near the theoretical points, as at the passage of a river, valley, or road. The stations appear to have been quite disregarded. Housesteads, for instance, does not affect the chain of mile-castles in its vicinity, being in one of the mile intervals. The original number of these structures was about eighty.

Turrets.— There is reason to think that these structures were numerous, but the remains of few are known. Even in Horsley's time, "scarce three of them could be made out in succession"; and, sixty years later, Hutton inquired in vain for them. But during the last half century or more, three — at East Brunton, Black-Carts, and Mucklebank, near Walltown — have been excavated, and others have been described. They appear to have been unequally distributed, and to have been placed where look-outs were required. To judge from the few which have been examined, they were, like the mile-castles, part and parcel of the structure of the Wall — small rectangular buildings, with an internal area of about 12 by 10 ft., recessed into its inner side, the remaining three sides being about 3 ft. thick, with a narrow doorway to the south.

The excavation of the Mucklebank turret by Mr. J. P. Gibson in 1892 not only threw much light on these obscure structures, but bore further witness to the vicissitudes through which the Wall passed. A succession of three ground floors, with intervening fallen débris and charcoal, pointed to two epochs of disaster. The lowest floor was of beaten clay, hardened by fire or mixed  p125 with ground brick; the second and third were flagged. Embedded in the débris above the third floor were heavy slabs of freestone, which Mr. Gibson attributed "to the floor of an upper chamber or possibly, the continuation of the path along the top of the great wall over or through the turret." These slabs, he suggested, had been supported on wooden joists; and from the large iron nails found about them, he concluded "that a great portion of the upper part of the turret must have been constructed of wood." No trace of an external or internal stair was found, so that the upper floor was probably reached by a ladder in the lower chamber.16

The Mural Road.— The function of this road was to provide a means of communication between the stations and mile-castles. Its ridge is best preserved in the hilly districts; elsewhere it is mostly obliterated or buried, but here and there its remains have been disclosed by the spade.​17 Its usual position seems to be from 60 to 100 ft. to the south of the Wall; but here and there it recedes, especially where the surface is uneven, in order to gain gentle gradients. Its contact with the stations is not always clear. At Carrawburgh, which is a north-and‑south fort, it apparently entered by the lateral gates, and so coincided with the via principalis. At Chesters, however, it could not have entered by these gates, as they were immediately north of the Wall; so that if it threaded the station, it must have passed through the subsidiary east and west gates. At Housesteads and Great Chesters, two east-and‑west stations, the road is usually shown on plans as passing through their end gates.

In serving the stations and mile-castles the road necessarily clung to the Wall, and thus more or less participated in its sinuosities. Hence in the hilly region, where the Wall zigzagged and swung considerably to the north, it would be neither a direct nor an easy means of communication between distant points. To provide a 'through' route from lowland to lowland, the road now known as the Stane Gate was constructed. It left the Wall in the neighbourhood of Chesters, and regained it west of Carvoran, its more direct course compared with the circuitous sweep of the former, likening it to the string of a bow.

 p126  The Vallum.— This great earthwork consists of a broad ditch, with its upcast disposed to form a series of mounds running parallel to it, two larger set back from the sides of the ditch, and a smaller, cresting one of the brinks — the south brink, according to the books — but not always present, or at all events not always noticeable. Here and there the Vallum is an imposing object, vying with the Wall itself in conspicuousness. In several places it has been cut through of late years, notably at Heddon-on‑the‑Hill and Downhill, near Halton, by the Newcastle Society of Antiquaries;​18 and at Appletree, near Birdoswald, Bleatarn, near Crosby-in‑Eden, and Brunstock, near Carlisle, by the Cumberland and Westmorland Society.​19 A comparison of the sections disclosed by these cuttings with the surface-indications generally shows that its form and dimensions varied little. The ditch was flat-bottomed like that of the wall, only smaller, being about 30 ft. in width across the top, from 10 to 12 ft. across the bottom, and about 7 ft. deep. The larger mounds vary considerably in width and height in their present condition, due undoubtedly to their unequal 'spread' since Roman times; and to this cause must, in some degree at least, be assigned their varying distance from the ditch. Where best preserved they are still 6 or 7 ft. in height. Their average width is about 30 ft. and distance from the ditch about 25 ft., the total width of the whole work averaging 130 ft. From its intermittent character it has been supposed that the small marginal mound is not part of the original scheme. It seems to the writer, however, that its purpose was to bring the sides of the ditch to a common height. Where the ditch is cut through approximately level ground, it is not seen; where the ground sinks to one side, there it is most conspicuous; and as the slope is generally to the south, this explains the prevailing view that it is confined to that side. Mr. Gibson confirmed this surmise, stating that where the ground falls to the north, the marginal mound is on that side, "showing that it was always made on the lower side of the ditch, to level it up to the opposite side."

The behaviour of the Vallum to the stations has an important bearing on the question of its origin and use. It has long been  p128 observed that it is indistinct or even obliterated in their vicinity; and this has given rise to the belief, reasonable enough, that whatever its purpose may have been, it fell out of use and was levelled at these places before the close of the Roman period. The excavations at Birdoswald and Carrawburgh in 1896‑7, showed that the ditch of the Vallum in their neighbourhood had been purposely filled, unlike the ditches of these stations which had been gradually silted up. These excavations also afforded some ground for thinking that the Vallum mounds had been omitted in these places, but this is a point which requires further elucidation.

The obliteration of the Vallum is responsible for some wrong impressions as to its relation to the stations that stand across its line or otherwise seem to touch it. There are stations that lie beyond its extremities, as Wallsend and Newcastle in the east, and Drumburgh and Bowness in the west; and there are intervening stations that are off its line. Of the residue, Benwell, Rutchester, Halton, and Chesters are so placed that their southern ramparts appear to be in line with the Vallum; while Carrawburgh and Birdoswald stand across it. The old view assumed that these stations were in actual contact with it. The excavations referred to, however, have shown that the Vallum curiously avoids them by skirting round them. But the method of deviation differs. At Carrawburgh, the Vallum ditch runs parallel with the proper ditch of the fort, forming, in fact, a second ditch round its southern half; while at Birdoswald it describes an irregular southerly semicircle. About a third of a mile east of Rutchester the Vallum was found to make a slight southerly bend, sufficient to carry it about 200 ft. south of the station. At Halton, trenching in the immediate vicinity of the station failed to find it, and the inference is that here also a deviation carried it some distance to the south. A later excavation at Walton proved that instead of pursuing its natural course north of the station, the Vallum purposely deviated so as to pass round its southern side. This curious behaviour is not confined to the stations. In following up its straight line east of Birdoswald in 1898, the excavators found it to abruptly turn southwards upon approaching a mile-castle.

The purpose of the Vallum has long been a subject of controversy, and if recent research has not provided a solution, it has  p129 at all events rendered several popular views untenable, and so has paved the way for further advance. The 'authorized' view, which is really as old as Horsley, who saw in the Vallum "a fence against any sudden insurrection of the provincial Britons, and particularly the Brigantes," has been pronounced against by such high military authorities as the late Lieut.-General Pitt-Rivers, General Von Sarwey, Military Director of the Limes-commission of Germany, and Sir William Crossman. The peculiarity of the Vallum in avoiding the stations also tells against the theory which gives a pre-Roman origin. The detours at Carrawburgh and Birdoswald clearly prove that the stations were already there, or were contemplated, when the Vallum was made. But apart from this, the lay-out of this earthwork in long straight sections is characteristically Roman. The theory that it was raised to protect the builders of the Wall is perhaps the least tenable of any, for the labour expended upon it would surely have been better employed upon the construction of those portions of the Wall where the frontier was most vulnerable; but apart from this, it is admitted by all who see in this work a defence, that it was a defence against the south, whereas the chief danger that beset the builders was from the north. More likely is it that the necessary protection was afforded by the numerous temporary camps which may still be traced in the vicinity of the Wall. The theory that the Vallum ditch was a sunken road is also unfortunate, for no excavation has yielded a trace of a roadway in this position or anywhere between the mounds; and apart from this, there is the insurmountable difficulty that the stations, which should be connected by such a road, are sedulously avoided.

A recent theory makes this earthwork a civil boundary, and this had the support, tentatively at least, of the late Prof. Mommsen, and is advocated by Dr. Haverfield.​20 Mommsen suggested "that the Vallum marks the southern or inside edge of the limes or 'frontier strip' of the empire," the two works, Vallum and Wall, being regarded as contemporary, but the one a legal, and the other a military line. Dr. Haverfield, in reviewing the discoveries of 1894‑5‑6, came to a similar conclusion, but guardedly added that "it is not, it is true, very definite, but it is much nearer a definite conclusion than we have before  p130 been able to go." Later, he surmised that its purpose "was forgotten or ignored even in Roman times," and in support of this he instanced the evidence of the early filling up of the ditch "where its presence may well have been inconvenient, as near a fort." And in 1902​21 he regarded the Vallum as intended to mark off the military works of the Wall from the province behind; but he doubted whether this purpose was ever fulfilled.

The reader must draw his own conclusion as to the meaning of this "strange earthwork, the inscrutable Vallum"; but it is safe to predict that his verdict will be that the last word has not been said upon it.

The Turf Wall.— The discovery of the remains of a turf wall in 1895 "introduced," as Dr. Haverfield puts it, "a new factor into the whole Mural problem." It had long been observed that for about a mile west of Birdoswald a ditch ran parallel to the Vallum at about 90 ft. to the north; and this was usually regarded as a supplementary defence to that work. But a series of transverse trenches disclosed the remarkable fact that it appertains, not to the Vallum, but to a former turf wall.​22 This ditch was found to be from 30 to 33 ft. in width across the top, about 10 ft. deep, and roughly V‑shaped, with convex sides and a flat bottom about 20 in. wide. The upcast had been spread out beyond the north lip, and the wall was set back some 10 ft. behind the opposite lip. The latter appeared to have been 12 or 15 ft. wide, and its still remained 2 ft. or more in height here and there. From the manner in which the dark matter was spread out on each side, it was concluded that it had been purposely destroyed. This wall deviates from the stone wall at Wall Bowers 1½ miles west of Birdoswald, and rejoins it nearly ½ mile east of that station. The western junction was obliterated by quarrying operations, but the eastern was still traceable. At this point the stone wall makes a bend, the eastern limb being in the straight line of the turf wall, and the western diverging from it on its northern side. The ditch of the latter was found to pass under the western limb and on the other side to coincide with the ditch of the eastern limb. It was evident that the turf wall was the older, and that the later stone wall was planted on its line eastwards of the above point, but took a new line westwards.

 p131  The relation of the newly discovered turf wall to the Birdoswald station is equally remarkable. On either side of the fort it was found to approach the north side of the great lateral gates, and its course was traced through the intervening internal area.​23 It is clear, then, that the turf wall is not only older than the stone wall, but also older than the fort, at least in its final condition. We have already observed that the latter was either already in existence or was contemplated, when the Vallum was made, for this deviates to avoid it. Was the Vallum an appendage of the turf wall or of the stone wall? It will be observed that it is approximately parallel to the former, not to the latter; and that this is its normal behaviour to the latter elsewhere, where the configuration of the ground does not necessitate deviations. This tells in favour of the contemporaneity of the Vallum and the turf wall, and its priority to the stone wall. If so, the Birdoswald fort must have been originally smaller and probably of earthwork, and was reconstructed in stone and extended northwards when the stone wall was built.

Before the discovery of the turf wall, Mr. Cadwallader Bates conjectured with singular insight, in his History of Northumberland, that the anomalous ditch near Birdoswald related to a turf wall which stretched from sea to sea, and which elsewhere along its line was subsequently replaced by one of stone, the stone wall here taking a more northerly course for some reason or other; and Prof. R. C. Bosanquet has also recently expressed his belief that this turf wall extended across the isthmus.24

Enough has been said to show that the Wall-system did not attain its final form at one bound. It embodies works and modifications of different times, all Roman, of course. Agricola appears to have recognized the strategic importance of the isthmus, but as he contemplated nothing less than the conquest of the whole island, it is hardly likely that he entertained a continuous fortification across it. The construction of a barrier could only have been entertained after the conquest of the northern part of the island was definitely given up.

The first emperor whose name appears in connexion with the Wall is Hadrian. In four of the mile-castles have been found inscribed tablets in his honour, placed by order of his propraetor,  p132 Aulus Platorius, and presumably there were similar tablets in other mile-castles. Some of the stations may have been such of Agricola's camps as happened to be in the line of the projected wall; but we cannot imagine a prior existence for the mile-castles — they are integral parts of the Wall itself. If Hadrian erected these, that structure must have been already determined upon. We know that when this emperor visited our shores in A.D. 120, the province was in a disturbed and unsafe condition, and we also know that his general policy was one of consolidation rather than expansion. It is true that no contemporary writer mentions his building a wall in Britain; but a century and a half later, Aelius Spartian states that "Hadrian went to Britain and put straight many things which were crooked therein, and was the first to draw a wall eighty-thousand paces, to divide the barbarians from the Romans."

But the same writer tells us that Severus, during his visit more than eighty years later, also built a wall — "the greatest glory of his reign is that he fortified Britain by a wall drawn across the island and ending on both sides with the ocean," — and this is reiterated by a succession of subsequent writers. But, as in the case of Hadrian, no contemporary writer records such a work on his part; still more remarkable is it that both Dio Cassius, writing a few years after his death, and Herodian a little later, should describe his Caledonian campaigns in graphic terms, yet make no allusion to his wall-building.​a

The wall thus attributed to Severus was certainly not the Antonine, which, as we have seen, was undoubtedly the work of Pius, and was soon abandoned; moreover, it has yielded little evidence of rebuilding or restoration. It cannot have been, as has been suggested, that Hadrian built the stations and the Vallum, and Severus the stone wall; for the recent excavations have proved that the Vallum was either a coeval or a subsequent work, or, if constructed previously, was planned with a view to the latter. It would be more reasonable to reverse the order and to say that Hadrian built the stone wall with its appendages, and Severus the Vallum.

That Severus had something to do with the barrier of the lower isthmus, is, however, beyond question. It is true that no inscription to him has been found upon the wall itself; but his name is inscribed upon Cumberland quarries, and upon slabs at  p133 Hexham, Risingham, and Old Carlisle. The Risingham tablet is noteworthy, as it records his restoration of a gate and the wall of the fort. Between Hadrian's day and that of Severus there had been troublous times; and it is likely enough that the second emperor found the Wall in a ruined condition, and that he not only restored, but strengthened it.

If we accept this view of the part played by Severus, there will be little difficulty in also accepting as literally true the statement that it was Hadrian who "first drew a wall, etc."; in other words, in assigning to this great emperor the initiation of the general scheme of wall forts, mile-castles, and vallum.

Communications and Supporting Forts.— This frontier system would be of little use without the means of expeditiously reinforcing its garrisons. It was particularly important, also, that York, the chief military centre of the north, and, in late Roman times at least, the seat of the official who had charge of the northern frontier, should be in easy touch with the whole length of the Wall. The map, Fig. 39, shows that these means of communication were admirably provided. From York proceeded a line of road in a north-north‑westerly direction, which by a prime bifurcation above Catterick and subsequent ramification, reached the Wall at Newcastle, Halton Chesters, Carvoran, and Carlisle, points roughly equidistant, and in addition an extreme easterly branch ended at South Shields, where a strong fort guarded the south side of the estuary of the Tyne. By these means, in conjunction with the transverse Stanegate and Mural Road, troops could be expeditiously massed at any point along the wall. The main artery from York to Catterick, with its continuation to the north (the Northern Watling Street), and its great branch to Carlisle, were portions of the first and the fifth routes of the Antonine Itinerary.25

Of less, but still of great importance, was access from Chester, and this was provided by a line of road on the western side of the Pennine range, which coincided in part with the tenth Antonine route. This joined the road from York to Carlisle at Kirkby Thore, and so participated in its connexions with the western portion of the Wall. Another important road linked Papcastle and the fortified Cumbrian ports of Maryport, Moresby,  p134 and Muncaster with Carlisle, and by a short western branch with Bowness on the Solway at the western end of the Wall.

All these roads, especially as they approached the Wall, were strongly guarded by forts, which formed an inner belt of frontier defence, well capable of stemming an incursion of the barbarians into the province until reinforcements arrived, should the Wall have been successfully assailed.

Several roads crossed the line of the Wall. The two most important of these were the Northern Watling Street, which, traversing the eastern lowlands of Scotland, had its destination  p135 in the eastern end of the Antonine Wall; and the continuation of the road from York to Carlisle above referred to, which appears to have reached that barrier at its opposite extremity by a devious and obscure route. On the former road were two important forts, the one at Risingham, and the more distant — twenty-two miles from the Wall — at High Rochester, the Antonine Bremenium. At similar distances on the other road were also two forts, the one, reached by a short branch road, at Netherby, and the other at Birrens, near Middleby, probably the Antonine Blatum Bulgium. These forts were of such size and strength as to render it almost certain that they were charged with something more than the keeping open of routes to the north, which would naturally lose importance when the Antonine Wall was evacuated. They were of strategic value to the Hadrian line. The more vulnerable parts of that line lay east and west of the central hilly region; moreover, there was the possibility of it being outflanked by the passage of an enemy across the estuary of the Tyne and the Solway. High Rochester and Risingham were well placed to check an advance upon the eastern portion of the Wall and the mouth of the Tyne; still better placed were Birrens and Netherby, with regard to the western third of the line and the Solway, the weakest part of the frontier. These four extra-mural forts may, therefore, be considered outposts and integral parts of the Mural scheme.

The Later Frontier.— There is some evidence that in late Roman times the Wall west of Birdoswald ceased to be held or regarded as part of the frontier scheme. In the Notitia Dignitatum​26 is a list of the stations and of the corps that occupied them, which were under the control of the Duke of the Britains, and among these is a series per lineam valli. By comparing the latter with the inscriptions found in the stations along the Wall which name their garrisons, it has been possible to identify the following: Wallsend, Newcastle, Benwell, Rutchester, Halton Chesters, Chesters, Carrawburgh, Housesteads, Chesterholm, Great Chesters, Carvoran, and Birdoswald, respectively with the Notitia Segedunum, Pons Aelii, Condercum, Vindobala, Hunnum, Cilurnum, Procolitia, Borcovicus, Vindolana,º Aesica, Magna, and Amboglanna.

 p136  When, however, this method of identification is applied to the stations west of Birdoswald, it fails to give satisfactory results. In the first place, it is impossible to crowd the remaining eleven stations per lineam valli of the Notitia into the remaining third of the Wall, even if we travel some distance from its actual line. Horsley tried his best, and found that he had still five to spare; and recently, Dr. Budge reduced this excess to four. But Bruce and Hodgson doubted whether two or three of Horsley's stations could be accepted as Mural forts at all. The fact is, this western length of the Wall and its forts are more obliterated and less fruitful in the evidences of long occupation than is the case elsewhere along the line, a circumstance which Bruce attributed to the interference of agriculture, this region being extremely fertile.

The inscriptions west of Birdoswald are few and tantalizing. The only corps common to them and the list is the Ala Petriana, inscriptions to which occur at Lanercost (on a rock), Carlisle, Old Carlisle, and Hexham. Of these, Lanercost alone, so far as sequence from Birdoswald goes, has the best claim to be the Petrianae of the Notitia, but the evidence for a station here is extremely vague, and all that the inscription proves is that this ala came for stone. Still this suggests that Petrianae was at no great distance. Accordingly, it is commonly identified with Castlesteads, at Walton; but, as Bruce points out, that station was too small for so large an ala, which was a thousand strong. Remains of stations occur at Brampton, Watchcross (according to Bruce, only a summer camp), Stanwix, near Carlisle, Burgh-on‑Sands, Drumburgh, and Bowness; but scarcely two writers agree as to their Roman names. There is evidence of another place in the vicinity of Birdoswald which is not mentioned in the document, and which may have been a Mural fort — Banna. An altar dedicated to Silvanus by the hunters of Banna has been found among the ruins of Lanercost Priory, which was built of Roman stones. This place is associated with Aesica on the Ravenna list;​27 and it also appears next to Amboglanna in the inscription of a bronze cup found at Rudge in Wiltshire, which also names two other Notitia places, Aballaba and Axelodunum. It is just possible that the Notitia Magna is a misspelling for Banna; if not,  p137 it might be identified with Castlesteads, Brampton, or Watchcross.

	DEO SANCTO SILVANO VE‑ NATORES BANNIESS To the holy god Silvanus, the hunters of Banna.
Altar to Silvanus, found at Birdoswald in 1821. Photo © Jona Lendering 2009, by kind permission.

On the other hand, there is fair evidence that the remaining eleven places of the Notitia were not on the Wall at all, but lay to the south-west and south. For instance, inscriptions to corps at these places have been found as follows: to the Second Cohort of Thracians at Moresby, and to the First Cohort of Spaniards at Maryport, two ports on the Cumbrian coast; to the Third Cohort of Nervians, at Whitley Castle; to the Sixth Cohort of the same at Brough near Askrigg; and to the Cuneus Armaturarum, at Ribchester in Lancashire. The evidence of the Antonine Itinerary points in the same direction, the Notitia Glannobanta, Alionis, and Bremetenracum,º being the Glannoventa, Alonis, and Bretemnacumº of its tenth route, and these lay far away to the south of the Wall.

The trend of evidence is strongly suggestive that the garrisons of the western portion of the Wall were withdrawn before the date of the Notitia, that is, before the 5th century. We know that towards the close of the Roman era, our shores were increasingly subject to attacks from the sea; and the long indent of the Solway must have rendered the Cumbrian coast peculiarly liable to descents from the contiguous coasts of Scotland and Ireland. Once a foothold gained on that coast, the valley of the Eden would afford easy access to the heart of the country. This liability of the western portion of the Wall to be outflanked must have greatly reduced its value; whereas the coast-forts of Cumberland and those along the eastern fringe of its highlands would be admirably placed to check these incursions. We can well imagine that these forts would be regarded as part of the northern frontier system — as a continuation, so to speak, of the eastern two-thirds of the Wall which continued to be held, and in this sense there is nothing incongruous in their being scheduled per lineam valli by the Notitia compiler.

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The Author's Notes:

1 Pp157‑66.

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2 Roman Lancashire, p14.

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3 Antonine Wall Report, p2.

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4 Ib. p123.

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5 Ib. pp76, 83.

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6 Ib. p128.

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7 Ib. p127.

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8 Antonine Wall Report, p132.

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9 Ib. p138.

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10 Ib. pp71 and 80.

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11 Ib. p148.

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12 Roman Wall, 1867, p51.

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13 Ib. p55.

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14 Roman Wall, pp202, 225, 230.

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15 per Mr. F. G. Simpson.

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16 Arch. Aeliana, XXIV, p13.

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17 For the peculiar construction of this road, see Roman Era in Britain, Chap. ii.

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18 Arch. Aeliana, N.S. XVI.

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19 Cumb. and West. Arch. Soc., 1895, p456; 1896, p191; 1897, p415; 1898, p174; 1899, p351.

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20 Cumb. and West. Arch. Soc., 1899, p341.

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21 Athenaeum, No. 3881.

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22 Cumb. and West. Arch. Soc., 1896, p185.

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23 Ib. 1898, p180.

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24 Arch. Aeliana, XXV, p243.

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25 A road-list of probably the latter part of the 2nd century. See Roman Era in Britain, Chap. i.

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26 Compiled about the beginning of the 5th century. See Roman Era in Britain, Chap. i.

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27 Compiled in the 7th century. See Roman Era in Britain, Chap. I.

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Thayer's Note:

a Dio Cassius: LXXVII.11 ff.; Herodian: III.14.

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