CHAPTER VIITHE PERIOD OF TRANSITION: CYLINDRICAL TOWER-KEEPS

Thedevelopment of the castle during the twelfth century was governed, as has been explained, by the methods of attack which its defenders had to meet. The strong fortresses of the reign of Henry II., with their stone curtains and rectangular keeps, opposed to the enemy a solid front of passive strength which defied attack. Sufficiently provisioned, a small garrison was capable of holding out against a long blockade, and tiring the patience of the assailants, whose artillery could make but little impression upon the masonry of the castle. At the same time, the stone castle with the rectangular tower-keep does not represent a final point in the perfection of fortification. The early Plantagenet castles were, on the contrary, merely a departure from the ordinary type of castle, composed of earthwork and timber, in the direction of an organised system of permanent stone castles. They belonged to a transitional period; for, even while they were being built, improvements upon their most striking feature, the rectangular keep, were suggesting themselves. During the last twenty years of the twelfth century, lessons learned by the Crusaders from the traditional methods of fortification employed in the Eastern empire exercised a profound influence upon the military architecture of France and England; and the application of these lessons during the thirteenth century entirely altered the defensive scheme of the castle, until the plan of masterpieces of fortification like Caerphilly and Harlech presented an entire contrast to the plan of defensive strongholds like Norham and Scarborough.

The first necessity which had governed the development of fortification was that of enclosing the defended position so as to present an adequate barrier to attack. The bailey was surrounded with its palisade; while the palisaded mount, with its wooden tower, commanded—that is, overlooked—the operations of the defenders within the bailey, and provided a second line of defence, if the bailey were taken. As siege-engines increased instrength, stone-work took the place of stockading. The bailey was encircled by a stone wall with a certain number of towers on its circumference. It was sometimes divided into an outer and inner ward by a cross-wall, or, as at Ludlow (96), a large outer bailey was added to it, which formed a courtyard for barracks and stabling, and a protection in time of war for dwellers on the outskirts of the castle and for their flocks. A wall superseded the palisade round the mount, or a strong tower was built, either in connection with the mount or on a new site, which commanded the whole enclosure. Thus the passive strength of the castle was ensured. But stone walls and towers, however strong, were in themselves an insufficient protection, unless the defenders could keep themselves fully informed of the movements of the enemy. It was necessary that they should be able to command the field in which the besiegers worked, and especially the foot of the wall or tower on which the attack was concentrated. The battering-ram, the scaling-ladder, and the mine must be kept under constant observation. A first step towards this was the establishment of projecting towers along the wall at intervals. These flank the wall—that is, the outer face of the wall between them can be overlooked and protected by bodies of men posted upon the projection on either flank. At first, however, the system of flanking was far from perfect; and therefore the next step was in the direction of improving it, so that every portion of the outer surface of theenceintemight be covered by the fire of the defenders. This improvement, which we are about to trace, was effected gradually, (1) by a change in the form of the flanking defences themselves; (2) by their multiplication at more frequent intervals. The first of these changes begins to be noticeable during the later years of the twelfth century: the second was brought to pass in the first half of the thirteenth century, and led to further developments in the arrangement of the lines of defence.

The rectangular form of the keep and of the towers on the curtain was in two respects a drawback to the defence of the castle. In the first place, the salient angles of the masonry were liable to destruction by sap and mine. The parallel jointing of the stonework made the removal of fragments of stone by the bore or pick at these points a comparatively easy, if still laborious, task. In the second place, the angles of a tower or curtain, which were thus points of danger, were precisely the places which the defenders were least able to command satisfactorily. Each face of a rectangular tower commands the field immediately in front of it: the range of shot, from the point of view of each marksman, is in a direction at right angles to the face of thetower. Strictly speaking, the foot of the whole curtain and its towers lies within a “dead angle,” as vertical fire from the rampart is impossible; but the wooden galleries attached to the rampart obviated this difficulty. But, if the lines of two adjacent faces of the tower are produced, it will be seen that the space contained by these is out of the defenders’ range, and within it miners can work securely, while the main attack is directed against the faces of the rectangle. One obvious concrete illustration of this is seen at Rochester. When King John, in 1215, besieged the castle, he directed against it his stone-throwing engines. Finding that progress by this means was slow, he set his miners to work. A breach was made in the outer curtain, and the miners continued their operations on the tower, and eventually, after much difficulty, broke their way through it.192We can see to-day that the south-east angle of the tower has been rebuilt, and that the form of the reconstructed turret is round, and not square. This, no doubt, marks the place where the breach was made: the repairs are evidently part of the work taken in hand by Henry III. in 1225.

A further weak point in the defences of the castle was the insufficient flanking of the curtain. In the eleventh century, as we have seen, flanking towers were discouraged by feudal over-lords, who rightly recognised the danger which a strongly fortified castle, in the hands of rebels, might mean to themselves. As time went on, stone curtains were provided with towers; but these were not many in number, and, so long as the rectangular form of tower continued in fashion, long spaces of straight wall were left between the projections. The risk of providing too many salient angles was probably recognised by military engineers. From the flanking towers the adjacent part of the wall could be covered by the artillery of the defence; but, where a long interval existed between two towers, the wall mid-way was out of effective range. To protect these unflanked points in time of siege, a body of defenders would have to be kept on each spot. A twelfth-century castle, therefore, to be thoroughly defended, needed a large garrison to cover its numerous weak points. Any attempt to concentrate the defence upon one threatened spot might lead to the weakening of the defence at other points, of which the enemy would not be slow to take advantage.

Added to this was an inherent drawback in the normal plan of the castle. Its wards and keep provided a system of successive lines of defence, which caused an enemy immense troubleto pierce, but could not offer a combined resistance to him. In many castles, like Norham or Barnard Castle, the inner ward and keep were placed at a distant angle of the enclosure, and were protected from external attack by steep outer slopes and a river at their foot. In such cases, the wall of the outer ward offered the first resistance: the inner ward did not come into action until the enemy had entered the outer ward, and the defenders had to retire to the inner enclosure. If the inner wall was breached or stormed, the keep gave the defence its last shelter. At Château-Gaillard, as has already been described, the chief feature of the siege was the capture of ward after ward: the defenders, in despair, did not even attempt to resort, as a final resource, to the keep. Château-Gaillard was in its own day a model of scientific fortification. Its fall was therefore a very striking example of the disadvantage of successive lines of defence, of which only one could be effectively used at a time. It is true that here and there, as at Rochester, the keep was placed so near the curtain of an outer ward that the exterior of the castle could be commanded from its battlements, and its artillery could be brought into play over the heads of the defenders of the curtain. At Richmond, the great tower commands the one side of the castle from which attack was possible, and was thus placed in the very fore-front of the defence. But such arrangements were happy ideas which occurred to individual engineers, and do not imply any systematic advance in the science of defence.

Château-Gaillard; Plan

The experiences of the earliest Crusaders brought the warriors of the west face to face with methods of defence far superior to those employed in England and France. The city-wall ofAntioch gave them an example of a perfect system of flanking defences; and, in the tripleenceinteof Constantinople they saw how successive lines of defence could be used in co-operation. At Antioch the wall was flanked at frequent intervals by fifty towers. Each of these, rising above the curtain, commanded not only its space of intermediate wall, but the rampart-walk as well. The rampart-walk, moreover, passed through the towers, which were protected by strong doors. To gain the whole line of wall, therefore, it was necessary to occupy the towers, each of which could be converted into a separate stronghold, isolating the intermediate rampart-walk. The siege was badly conducted, the Crusaders limiting themselves to a strong position between the city and the Orontes, and allowing the defenders to hold their communications on two sides of the city open for some five months. Posts of observation were eventually established on the two neglected sides; but the actual capture of the city was due to the treachery of one of the commanders of the Turkish garrison, who admitted a body of Franks into one of the towers in his charge. They made their way into seven more towers, and so gained access to the city.193The three walls of Constantinople surrounded the whole city: each was higher than the one outside it, so that all three could be used simultaneously by the defenders.194Against such a system of concentric defence, the besiegers were manifestly at a disadvantage.

These lessons from the east, stimulating though they were, did not produce their full practical effect for some generations in the west. Our engineers had to pass through a long epoch of gradual experiment before they could arrive at a finished system of flanking or of concentric lines of defence. The traditional mount-and-bailey plan provided the foundation of the plan of the stone castle. The traditional importance of the keep as the ultimate place of refuge dictated the arrangement of ward behind ward, culminating in the great tower. Meanwhile, the improvement of flanking defences led more and more to the concentration of engineering skill upon the curtain, so that the keep gradually took a place of secondary importance. As an obvious result of further improvement, the keep was dispensed with, and the whole attention of the engineer was directed to combining the defences of the castle into a double or triple line of simultaneous resistance to attack. These steps took time: the transition from one to the other was effected by no sudden revolution, but by work along old lines, a work of revision andimprovement, until the finished product formed an almost complete antithesis to the source from which it was derived.

The earliest signs of transition in England are seen in the strengthening of the masonry by the reduction and elimination of salient angles. It is obvious that, if a rounded or polygonal form is given to a projecting tower, or if the angle of a rectangular tower is rounded off, a wider field will be commanded by the artillery of the defence. The new range will be a large segment of a circle radiating from the centre of the tower, instead of a rectangle in front of each face. The sectors at the angles within which an attacking party can work securely will be thus eliminated, and the chances of the success of a mine will be less. The masonry also will offer much greater resistance to the battering or boring engines of the enemy. The joints are no longer parallel, but radiating, so that it becomes much harder work to force out stones and effect a breach. The obtuse angles of polygonal towers, with the joints of the masonry in the alternate faces running in oblique directions to each other, have a much greater power of resistance than the right angles of the ordinary twelfth-century tower.

The general use of circular and polygonal forms is first found in connection with the principal tower of the castle, the keep. The main object was at first, no doubt, the greater cohesion imparted to the masonry: the scientific advantages, from the point of view of artillery, probably were not realised till later. In France the cylindrical donjon appeared at an earlier date than in England: that at Château-sur-Epte (Eure) is said to have been begun in 1097.195The tower of Houdan (Seine-et-Oise) is a cylinder flanked by four cylindrical turrets: it was built during the reign of Louis VI. (1108-37),196and the form shows that the builders looked, not merely to the strength of the masonry, but to the reduction of the enemy’s chances of successful attack. The majority, however, of such donjons in France belong to the second half of the twelfth century and the beginning of the thirteenth, and were contemporary with our rectangular towers. But the engineers of Henry II., to whom we owe so many of our stone keeps, were certainly acquainted with the possible benefits of forms other than square. The keep of Orford in Suffolk was probably built between 1166 and 1172,197and is therefore earlier in date than many rectangular keeps.

Conisbrough; Keep

Internally, it is cylindrical; externally, a polygon of twenty-one sides, with three very large rectangular turrets projecting from it. It has a basement and two main floors, and is entered by a two-storied fore-building, which forms a southward continuation of the eastern turret. The sloping base of the tower is continued round the turrets, and greatly strengthens their angles; while the turrets themselves are so placed as to flank the whole tower and fore-building very effectively, and to provide additional room in the interior. This combination of the rectangular and polygonal forms is, for its date, an unique departure from the ordinary type of English tower-keep. But it must be remembered that the shell-keep on the mount usually took the form of a cylindrical or polygonal wall strengthened by buttresses; and at Orford, where the tower appears to stand upon the base of a levelled mount, we may have a conscious adaptation of this form to the heavier and loftier tower. At Gisors (Eure) the older donjon was an octagonal tower, built on a mount, and surrounded by a circular wall. The tower was probably built by Henry II. between 1161 and 1184,198within the somewhat earlier shell, and took the form which was best suited to the artificial soil on which it stood. But there are at least two instances of English rectangular keeps in which a slight departure from the normal form was made for obvious purposes of additional strength, without reference to an artificial site. At Newcastle the north-west turret is octagonal, with very obtuse angles. In the small tower of Mitford, on the Wansbeck above Morpeth, the north wall is built with an obtuse salient angle, so that the tower forms an irregular pentagon. The date of this tower cannot be fixed with certainty, but it probably belongs to the second half, at any rate, of the twelfth century;and it can hardly be doubted that the object of this peculiar device was to give the defenders better command of the angles of the tower which were exposed to attack from the inner ward.

Conisbrough; Keep. Plans

Somewhat later than these is the noble cylindrical keep of Conisbrough (166), which is attributed to Hamelin Plantagenet, a natural brother of Henry II., and husband of Isabel, heiress of William, earl of Surrey. Hamelin died in 1201: the tower was built, as the architectural details show, during the last quarter of the twelfth century. It is a regular cylinder; and to its circumference are applied six bold buttresses, which narrow slightly outwards,and rise above the parapet in turrets. The whole is built of dressed stone in large rectangular blocks, the fine condition of which, after more than seven hundred years, is extraordinary. The construction is unusually solid: the thickness of the wall in the basement exceeds 20 feet. On the first floor it is just under 15 feet: in the two upper floors it is reduced by internal off-sets, until, at the rampart level, 75 to 80 feet above the ground, it is 12½ feet. In addition to this the buttresses, which project 9 feet at the basement level and 8 feet above, are not used, like the turrets at Orford, to contain additional rooms, but are built solid. The chapel, however, was formed by constructing a chamber in the eastern buttress upon the third floor.

Conisbrough; Fireplace

The tower of Conisbrough, like that of Orford, was intended for residential as well as defensive purposes; but light and comfort were sacrificed to military necessities. The entrance, as usual, was upon the first floor, but there is no trace of anyfore-building, nor is the original means of approach at all clear. The basement was simply a domed well-chamber and store-room: the only approach to it from the first floor was an opening in the centre of the guard-chamber, over which was probably the windlass by which buckets were lowered into the well.199The first floor was a guard-chamber: there were no windows, and the only means of admitting daylight was through the open door on the far side of the passage through the wall. On the right-hand side of this passage, a curved stair mounts through the thickness of the wall to the second floor, which it enters by a landing in the embrasure200of a loop on the north side. This floor was the hall of the keep. There is a large fireplace (168) in the west wall, with a spreading chimney-breast, and a lintel of joggled stones resting on triple shafts with carved capitals. In the wall between the fireplace and the entrance is a rectangular recess, containing a small sink, which was drained through the wall. There are two windows, the loop close to the entrance, and a double window opening to the south-east. The embrasures are barrel-vaulted: that of the double window has a stone bench on all three sides, and stands three steps above the floor of the hall. This window was not glazed: the upright between the two rectangular openings has at the back a rounded projection, through a hole in which the bolt of the shutters passed, and the fastening was further secured by a wooden draw-bar. On the north-east side of the hall a winding passage with two turns and a flight of steps leads through the thickness of the wall to a garde-robe.

To reach the third floor, the hall had to be crossed to a recess in the direction of the south-west buttress. From this point a curved staircase mounted through the wall to the embrasure of a loop in the south-east face of the third floor. The apartment on this floor contained a smaller fireplace, immediately above that on the second floor, and treated with similar architectural ornament. The flue of the lower chimney runs up through the wall behind that of the other: the common chimney-top projects from the rampart-walk above. There is also upon this floor a trefoil-headed recess with a sink. There are two windows, the loop in the south-east face, and a double opening, similar to that below, looking south. This room corresponded to the “great chamber,” which is found in the larger houses of the middleages. On its east side the chapel, an irregular hexagon, vaulted in two ribbed bays with a transverse arch between, was constructed in the eastern wall and buttress. The details of its beautiful capitals, like those of the fireplaces, show elementary foliage of the water-leaf type, such as is found in the chapel of the tower at Newcastle (152). Chevron is used in the stilted transverse arch and round the outside of the arch of the loop at the east end. The quatrefoil openings north and south of the chancel bay, and the trefoil-headedpiscinaein the same walls, are of an advanced transitional character; and, by comparing these details, a date approximating to 1185-90 may with some certainty be given to the tower. In the north wall of the chapel a doorway leads into a small vestry or priest’s chamber, lighted by a loop. The stairway to the rampart-walk mounts through the wall above this chamber, and its head is above the western bay of the chapel. It is entered from a recess in the north-east wall of the second floor, and from this recess there is also a zigzag passage to a garde-robe, the seat of which is corbelled out in the angle between the north-east buttress and the north wall of the tower. The two lower stairways and the two garde-robe chambers are each lighted by a small loop.

In the roomier arrangement of the keep at Orford, the stair is a vice in the turret or buttress to which the fore-building is annexed. The chapel is upon the first floor of the fore-building, and, being on a level of its own, not corresponding to the levels of the tower, is approached from the stair by a separate passage. The entrance to the chapel is a doorway on the left of this passage, which is continued through the south-east wall of the tower to a priest’s room in the south turret.

The defensive side of the arrangements at Conisbrough must now be considered. The tower stands close to the north-east corner of a large bailey, the shape of which follows that of the knoll on which it is built: the north segment of the tower, with the two adjacent buttresses, continues the line of the curtain; but five-sixths of the circumference, with four of the buttresses, are within the enclosure. On the north and east sides the steepness of the hill made access nearly impracticable, and the natural point of attack was from the south and south-west. The position of the keep is at the point furthest removed from attack, and the capture of the inner ward, as will be seen in a later chapter, was rendered very difficult by a well-guarded approach.201The tower stood on higher ground than the rest of the ward, and the entrance, on the south-east side, was sheltered by the east curtain. The south and south-west faces were fullyexposed to an attack from the inner ward, and it was on this side, therefore, that the defenders needed full command of the sides and base of the tower. Accordingly, when we mount to the rampart-walk, and examine the tops of the buttresses, we find that the two which are upon the north curtain, and were not exposed to attack, contain cisterns. The two on either side of the main entrance were not necessary for flanking purposes, as the entrance itself would be defended by some kind of platform in time of siege. One, therefore, above the chapel, was employed as a house for carrier-pigeons; while the other contained an oven, in which stones and arrows could be heated. The remaining two buttresses are raised platforms which effectively flanked that part of the circumference which was otherwise insufficiently guarded, and lay open to catapults and mining operations. The spreading base of the tower and buttresses served further to keep the battering-ram and bore from direct contact with the main wall of the tower, and improved the flanking position of the defenders; while missiles dropped from the summit upon this talus or sloping surface would rebound upon the enemy with deadly effect.

Above the talus the solidity of the main wall defied the force of catapults. These engines, however, had increased in strength and range, and it was no longer safe to give light to the tower in the somewhat lavish method adopted by the engineers of some of our large keeps. At Conisbrough, as we have seen, the walls of the first floor, save for the entrance passage, are absolutely solid. The loops in the upper floors are very few in number, and the one on the most exposed face is almost concealed by a buttress. The double window on the second floor is immediately over the main entrance, on a side which it would be difficult to command with a large siege-engine. That on the third floor is placed upon an exposed face, but would probably be out of range.202The garde-robe vents are on the side where the tower crosses the line of the curtain.

In time of siege the larger windows would be shuttered and barred. The defence would be conducted from the top of the tower, while a body of the garrison would be told off to protect the main entrance. The whole summit would be utilised. The defence was not confined, as in a rectangular keep, to the rampart-walk; but there was a rear-wall to the walk, through which openings probably gave access to a covered round-houseabove the third floor. To this room, which, to judge from contemporary instances, had a conical roof, arms and missiles could be hauled up, through trap-doors in the floors below, from the guard-room and the store-chamber in the basement. There was no vaulted roof in the tower above the basement, so that the flat roof could not be used as a platform for catapults. There is no indication that hoarding was employed outside the rampart. The tower and its buttresses were finished off with a battlemented parapet in the usual way; the buttresses, as has been shown, were so constructed and so near together that additional wooden defences were practically unnecessary.

Etampes; Donjon. Plan

GOODRICH CASTLE: round tower with spur at base

GOODRICH CASTLE: buttery hatches

In France the treatment of the donjon was pursued with more variation than in England. To the middle of the twelfth century belongs, for instance, the donjon of Etampes (Seine-et-Oise), which takes the form of a quatrefoil (172). The donjon of Provins (Seine-et-Marne) is of much the same date, the ground-plan forming an octagon flanked by four cylindrical turrets. Although both these towers have analogies in England, they were constructed nevertheless by French engineers at a period before even the rectangular tower had become common with ours.203They are also only two out of many diverse experiments. The cylindrical form, however, commended itself to the builders of the finest French examples. Château-Gaillard (163) follows closely upon Conisbrough in point of date, having been begun by Richard I. in 1196. The donjon is not, as at Conisbrough, a tower to which the line of a somewhat earlier curtain has been adapted, but is part of a homogeneous scheme of fortification. The site of the castle is the top of a very steep and almost isolated hill on the right bank of the Seine: the west slope is a precipice, and the only practicable attack could be made from the ridge joining the hill to the high ground on the south. The donjon is set so that its west face projects from the curtain of the inner ward, upon the very edge of the precipice. The interior forms a regular cylinder, and the west face is a segment of a circle. On this side the solidity of the masonry is increased by a tremendous outward slope or batter, the wholeheight of the basement and adjacent curtain. Towards the inner ward, however, the cylinder is strengthened by a covering spur, also battered, so that, while the interior of the castle was commanded from the rampart, the tower offered to the besiegers an angle of immense thickness and strength, immediately opposite the gateway of the inner ward. A possible prototype in France of this form of defence is the donjon of La-Roche-Guyon (Seine-et-Oise), higher up the Seine, where the spur covers about a quarter of the circumference of the tower. Philip Augustus adopted the same device a few years later in the White tower at Issoudun (Indre).204It is seen at Goodrich (174), Chepstow, and elsewhere.

Château-Gaillard

As the upper portion of the tower of Château-Gaillard is gone, its internal arrangements are difficult to decipher. It was purely a tower of defence; but the inaccessible nature of the west side allowed of large windows being made in that face upon the first floor. There was probably a low second floor, above which was the roof and rampart-walk. The rampart was defended with the aid of a device, unusual at the time, although very general at a later period. The sides of the tower within the ward were furnished with narrow buttress projections above the battering base, which gradually increased in breadth as they went higher. These divided the face of the tower into a series of recesses spanned by low arches, on the outer face of which the parapet was carried. The top of each recess, between the parapet and the wall, was left open, so that the defenders could use the holes for raining down missiles upon their opponents. Such holes, formed by corbelling out a parapet in advance of a wall or tower, are called machicolations (mâchicoulis),205and graduallysuperseded the external gallery of timber. Holes in stone roofs for the same purpose are found at an earlier date, as in the fore-building at Scarborough; and, as early as 1160, they appear in connection with the parapet of a donjon at Niort (Deux-Sèvres).206The general tradition is that they were invented by the Crusaders in Syria, where wood for hoarding was not easily obtained; and this is probably true.207They appear in a state of perfection, which testifies to a long course of previous experiment, at the great Syrian castle of Le Krak des Chevaliers (176), begun in 1202. But hoarding continued in use in Europe long after the building of Château-Gaillard, and even the donjon of Coucy (Aisne), by far the finest of all cylindrical donjons, was garnished with timber hoarding carried on stone corbels—an interesting example of the transition from one form of defence to another.

Le Krak des Chevaliers

Coucy

The cylindrical form of donjon was brought to perfection in France under Philip Augustus (1180-1223). At Gisors, which came into his hands in 1193, he built a new circular tower on the line of the curtain, which superseded Henry II.’s octagonal tower on the mount. His fortification of Gisors led directly to the building of Château-Gaillard by Richard I., to cover the approach from French territory to Rouen.208But in 1204 the capture of this great stronghold delivered Rouen into Philip’s hands; and in 1207 he built the donjon, now known as the Tour Jeanne d’Arc, at Rouen. Here we meet with thetower vaulted from basement to roof, with a strongly defended entrance at the level of the ward in which it stands, of which the most perfect example is found at Coucy.209Coucy, the work of a powerful vassal of the crown of France, represents a degree of scientific fortification to which none of our cylindrical donjons attains. The castle was constructed, like Conway at a later period, in connection with the defences of a walled town.210It consists of two wards, a large outer ward or base-court and an inner ward of irregular shape, with four straight sides of unequal length and round towers at the angles. In the middle of the east side, between the two wards, is the donjon (177), a cylinder of some 200 feet high—90 feet higher than the tower of Rochester. It stands isolated from the curtain of the inner ward, from the line of which about one-third of its circumference projects, and is surrounded by a ditch, originally paved with stone. To this ditch there was no external access. On the outer edge of the ditch, joining the east curtain of the inner ward at two points, was a strong wall orchemise. Outside this was theditch dividing the inner ward from the base-court. Within the inner ward, a low wall took the place of thechemiseof the donjon, and access to the tower was provided by a bridge across the stone-flagged ditch. The bridge was worked by a windlass, and, when not in use, remained drawn up on the threshold of the tower.

The donjon of Coucy is built in three stages, and has a large apartment, originally vaulted, on each floor. There is no basement chamber below the level of the entrance. In order to facilitate vaulting the various floors, each chamber was planned with twelve sides, lofty niches being left between the abutments of the vault.211Without giving a detailed description, we may notice the points in which this great structure resembles and improves upon the tower of Conisbrough. (1) The isolation of the tower, defended by its own ditch and, towards the field, by its own curtain, makes an entrance on the ground floor possible. In this respect, the builders of Coucy followed the example of Philip Augustus at the Louvre and at Rouen. (2) The defences of the entrance are more elaborate than at Conisbrough, where the doorway was closed merely by a strong wooden door, reinforced by two draw-bars, and a straight passage led into the guard-room on the first floor. At Coucy there was a similar door, but in front of it was an iron portcullis, worked from the first floor of the tower, and sliding through grooves at the back of the jambs of the doorway. The portcullis was defended further by a machicolation or open groove in the floor above. The entrance passage behind the wooden door was closed by a hinged grille at the entrance to the guard-room. (3) The stair, as at Conisbrough, was on the right of the entrance passage, but, instead of following the curve of the wall, was a vice, which led straight to the roof, communicating with the two upper floors on the way. The device adopted at Conisbrough, by which the stair ends at each floor, and, in order to ascend further, the floor has to be crossed, was adopted in the lesser towers at Coucy,212but not in the donjon. The Conisbrough method has the advantage, very desirable in a tower, of keeping the approach to the roof under direct observation throughout its entire distance: we find it used in the stairs of the rectangular keep at Richmond. (4) The tower of Coucy, as already noticed, wasdefended by a lofty parapet, pierced with arches, which, in time of siege, gave access to an outer wooden gallery supported by stone corbels.213The form of the corbels is that which became general in later times: each is composed of four courses of stone projecting one above the other, with their outer ends rounded. (5) The well at Coucy was in one of the niches between the abutments of the ground-floor vault. (6) There are garde-robes at Coucy on the left of the entrance-passage, and in a similar position at the entry to the first floor. (7) We have seen that at Conisbrough arms were probably transported from the basement to the roof through a series of trap-doors in the floors. At Coucy there was a circular opening left for this purpose in the crown of the vault of each floor. (8) The solidity of the tower of Coucy is emphasised by the absence of large windows, even more noticeable than at Conisbrough; and, although the tower contains fireplaces, its purely defensive character is unmistakable. It provided accommodation for an enormous garrison, but for residential purposes, it would have been uncomfortable to the last degree. It contains no trace of a permanent chapel: when the tower was in use, an altar might have been set up in one of the niches on the first floor; but the regular chapel was in the inner ward, and was connected with the domestic buildings.

In the walls of the tower of Coucy can still be seen the holes which served to attach the scaffolding during construction. The spiral course which they take shows that the scaffolding, rising with the tower, formed an inclined plane of a moderate slope, up which the necessary materials could be wheeled. The advantage of a cylindrical tower from this point of view is obvious. Another structural feature is the provision of gutters for the drainage of the roof in the stonework at the back of the vault-ribs of the second floor. The absence of any effective provision for draining the centre of the roof at Conisbrough points to the probability that it was sheltered, as already explained, by a conical roof of its own.

Pembroke

The introduction of the cylindrical donjon in England coincides with a period at which the keep was already beginning to disappear from the castle. The principal examples, which may be attributed to the early years of the thirteenth century, are on the frontier and in the south of Wales. Chief among them is the fine tower of Pembroke (180), which was probably built by William Marshal, earl of Pembroke and Striguil, about 1200.The castle of Pembroke was of great importance, owing to its situation upon an arm of Milford haven,214and its command of the passage to Ireland. The keep was probably the first completed portion of the present castle, the stone-work of which, as it stands to-day, is very largely of the late twelfth and early thirteenth century.215It is a round tower, with a basement and three upper floors, standing just within, but not touching, the curtain which divided the inner and higher from the outer ward. The height is 75 feet; the floors were of wood, but the uppermost stage was vaulted by a dome, which still remains, rising in the centre of the tower above the rampart-walk. The stair is a vice in the west wall, from the basement to the summit: the main entrance was upon the first floor, but there is also a basement entrance, which seems to have been pierced not long after the building of the tower. The whole structure batters upwards, and the walls are slightly gathered in at each stage on the outside, a method the reverse of that pursued at Conisbrough: the masonry is roughly coursed rubble. On each of the first and second floors there is, towards the inner ward, a two-light window with pointed openings, the spandrils between which and the enclosing arch are pierced with plate tracery. The third floor was lighted by windows pierced in the dome.216Commanding, as it does, thewhole interior of the castle, this tower is remarkably grand in situation; and its thick walls offered considerable resistance to artillery. It shows, however, no advance upon the defence of Conisbrough. The rampart-walk is narrow, and the dome in the centre prevented the employment of the roof as a platform.

Pembroke; Plan

The cylindrical donjon in England and Wales was simply an experiment attempted here and there, as an improvement upon the rectangular tower, but was never carried to the general perfection which it attained in France. Its isolation at Coucy, upon the outer face of the inner ward, protected by its own inner ditch, and covered by a strong curtain of its own, are signs of a perfection of engineering skill to which our builders did not attain. In one case, at Flint, we find a round tower which is isolated within its own ditch at one corner of the castle, but stands outside the main wall, and had no separate curtain of its own.217The plan strongly suggests a mount-and-bailey fortress, the isolated tower occupying the site of the mount, and the bailey walled in, leaving the moat, which was marshy and was filled with water at high tide, clear. The construction of this keep is peculiar: it is composed of an outer and inner circle of masonry, with barrel-vaulted passages between the two. Its actual date is unknown.218But, as a rule, where the keep stands upon the outer line of defence, it is joined by the curtain of the bailey. Thus at Caldicot, near Chepstow, the castle is simply a mount-and-bailey enclosure surrounded by a stone curtain of the thirteenth century. The keep is a round tower at one corner, standing upon the partially levelled mount; and the curtain crosses the ditch to join it on both sides. At Conisbrough, where the keep was on the line of the curtain; at Pembroke, where it stood just within the line, there was no ditch round it: the high ground on which it was placed seems to have been thought a sufficient protection.

There are, however, a few round towers which, although they have not their own curtain in the sense of Coucy, are yet within defences of a peculiar nature, and therefore stand in a class apart. The most remarkable of these is Launceston, where the tower stands upon the summit of a lofty artificial mount of early Norman origin, and is approached by a steep and well-defended stair, ascending the face of the mount to the main entrance. Round the outer edge of the mount remain the lower courses of a stone wall, concentric with the keep. Within this is another and higher circular wall, which was crowned by a rampart-walk, approached by a stair in the thickness of the wall, to the left of the entrance. Inside this enclosure is the tower itself, which now consists of a basement and a ruined upper floor. The narrow space between the tower and the encircling wall was evidently roofed over at the height of the first floor of the tower: holes for joists still remain.219This double circle of masonry recalls Flint, where, however, the intermediate passage was vaulted, and the outer circle was probably the whole height of the tower.220Flint does not possess the low outer wall which existed at Launceston. The nearest analogy to Launceston isat Provins (Seine-et-Marne), where the octagonal keep has its own outer curtain, and is composed of an outer octagon with cylindrical turrets at the angles, commanded by an inner octagon rising two stages higher. The upper stage at Provins is surrounded by a lofty crenellated wall, on which rests a conical roof.

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