THE CYLINDRICAL KEEP, c. 1170-1250

The latter part of the twelfth century and the earlier portion of the thirteenth was marked by the introduction of the Cylindrical Keep, forming a transition or connecting link between the Shell and the Rectangular Keeps of the previous period, and the remarkable development of castellation which occurred in the thirteenth century. The latter, however, must not be considered in the light of a sudden revolutionary change, inasmuch as many indications occur in the castles of the twelfth century which exhibit a tendency to break through the conventionalism then prevailing, and to produce works of a more complex character, suited to the progress in military methods of attack. The introduction of the Cylindrical Keep was one of these innovations; although it did not remedy the great fault inherent in Keeps generally, viz. that of impotence with regard to driving off the besiegers, yet it furnished a method which enabled the builder to effect a considerable economy in material and labour, while at the same time affording that strenuous passive resistance to assault which characterised the former styles. It is probable that King Henry II. was chiefly responsible for the introduction of the Cylindrical Keep, as by reason of his French birth he was acquainted with a number of foreign castles having citadels built upon this plan. These Cylindrical Keeps were likewise known as Donjons and Juliets, and attained to a degree of perfection upon the Continent which was never reached in the British Isles. The example at Coucy is probably the finest abroad.

The advantages which may be claimed for the Cylindrical Keep, apart from its lessened cost of construction, are the increased solidity, and the great difficulty in breaching it, or bringing it down by a mine. By vaulting each floor the resistance of the structure was increased; by enclosing the upper part in a similar manner also, the danger of fire from incendiary missiles launched upon the roof was practically nullified. A disadvantage, however, lay in the fact that the besieged could not concentrate a discharge of missiles against assailants at one part of the base without exposing themselves to the enemy's archery. This was to a great extent rectified by the bretasche, which, though in use previously, became established as a regular defence at this period.

These were timber galleries encircling the outer part of the tower at its summit, supported in position by strong beams of wood inserted in holes made for the purpose, and strengthened by struts resting upon corbels. Upon this foundation a wooden gallery was built, covered in by a sloping roof resting against the walls, and generally enclosing the summit of the wall. In suitable places the gallery was loopholed for archers and cross-bowmen, while through openings in the floor stones and other missiles could be dropped upon assailants at the foot of the Keep. It could be entered from the battlements behind, where stores of ammunition were placed.

At times two bretasches were in use, one above the other; the upper projected a greater distance from the walls so as to avoid injury to the lower. The unfinished appearance of the tops of many towers can be explained by their having been covered with a bretasche in former times, although this defence was not kept in position permanently but usually built upon the approach of danger. The machicoulis and alurs of a later date were imitations in stone of the wooden bretasche. At Coucy these defences were placed about 180 feet from the ground, and the nerve displayed by the defenders working at such a giddy height excites admiration.

The introduction of machicolation proper into England occurred in the latter part of the thirteenth century and became a prominent feature at that period. The faults inherent in the bretasche were the feeble resistance which it offered to missiles launched from the mangonels of the besiegers; the destruction of one part by a well-aimed stone would naturally expose the remaining defenders to archery, besides seriously weakening the rest of the structure, which depended to a great extent upon its continuity for safety.

Another weakness was the perishable nature of the material, which required constant renovation and addition, and to this circumstance may be attributed the fact that examples of the true medieval bretasche are extremely rare at the present day. A fragment remains over one of the gates at Coucy, while the position of the main beam may be seen upon the outer gate of Leeds Castle. At Norham Castle a small doorway appears in the upper part of the square Keep, the conjectured use for which is that it gave access to the bretasche. In many castles of the twelfth century still remaining a line of small openings in the outer wall at the top is visible; they indicate the position of the former bretasche, and are caused by the removal of stones for the insertion of the projecting beams. Notwithstanding the advantages inherent in the Cylindrical Keep, which prompted their erection in many parts of France and other parts of the Continent, we do not find one example forming an integral part in a British Castle of the first class.

Cylindrical Keeps were not always of a stereotyped form, and among the comparatively few erected in England there is marked diversity in detail. Launceston, for example, really consists of a triple defence; two outermost rings of walling, one of which is a dozen feet thick and nearly 30 feet in height, effectually prevent any attempt at mining the Keep proper, which stands a few feet within the second ring. It is now only a shell, but timber flooring once divided it into three stories. The walls are nearly 50 feet in height, about 10 feet thick at the base, and stand in a ring whose diameter is nearly 20 feet. The open spaces around the Keep were formerly covered by roofing.

Richard, King of the Romans and brother of Henry III., is generally credited with raising the Launceston Keep and also the companion one at Restormel. The Keep at Barnard Castle is remarkable for the huge projecting triangular spur, which, springing from the soil, rises to within a few feet of the parapet. The floors were vaulted. This circular Keep is about 50 feet in height and 40 feet wide. Pembroke Keep, on the other hand, rises without buttress or spur or concentric walling straight from a battering base at the ground-level to a height of about 70 feet to the spring of the vaulted roof. It trusted apparently to the enormous thickness of its walls, 20 feet at the base, to defy any attempts at mining.

Conisborough Castle possesses the most remarkable Keep of the cylindrical type in the British Isles, both by reason of its extraordinary plan and rare contour. It is a gigantic cylinder nearly 70 feet in diameter, and tapering upwards to a height of over 90 feet. Upon the exterior six enormous buttresses are arranged symmetrically round the face, projecting 9 feet from the surface and being 16 feet wide where they support the cylinder. They diminish in width, however, as they recede from it. These buttresses are carried up the whole height of the Keep, and thus, combined as they are with a massive base of masonry upon which the tower stands, and forming an integral portion of the wall which is about 12 feet thick, we have what is probably the most efficient protection against the deadly mine ever devised as a protection to a British Castle. It may be compared to six enormous spurs, the blowing up of one or even two but little affecting the stability of the remainder.

The entrance to the Keep is only a small square aperture placed in the first floor and approached by a long flight of steps in which at one time a drawbridge occurred. The ground floor contains the well and is entered by means of a trap-door in the vaulted ceiling. The buttresses are excavated in places to form chambers, and in one is situated the oratory described by Scott in Ivanhoe. It is beautifully vaulted in the Early English style, with carved capitals and bases to the supporting shafts. This grand relic of the feudal period was probably built in the reign of Richard I. by Hamelin Plantagenet, the natural brother of King Henry II., who had married into the de Warrenne family, the rich Earls of Surrey.

Another variety of the Cylindrical Keep was that at Orford, in Suffolk, which possessed a cylindrical shaft similar to that at Conisborough, and was supported by three minor towers symmetrically arranged and carried above the battlements. This Keep was protected at the base by a massive wall with a ditch between the wall and the Castle base, and probably suggested the Conisborough Keep and also that at Warkworth, while those at Wallingford, York and Pontefract approximated to the same ideal.