British History,Monarchs of Great Britain,King Arthur

The English Castle, Part 3
by David Dawson

This article is the third in a series which attempts to outline the development of the English Medieval castle and to describe its major features. Where possible, reference is made to existing castles within a comfortable day's journey of London so that the visitor who wishes to view a selection of English castles, but has limited time at his or her disposal, need not travel far from the capital



By the second half of the 12th Century the English Medieval castle had developed a form which we today would recognize as being that of a castle. It possessed a stone keep, shell or tower, and a gatehouse. Its enclosure or bailey was bounded by battlemented stone walls and defended by a ditch or moat. Yet events taking place far away from England were having a profound effect on castle design and were gradually to modify the form and structures of English castles in the next two centuries.

These events were the Crusades; attempts by the armies of Christian Europe to seize, and retain, control of Jerusalem and the other Holy Places of Christianity from the Saracenic Turks. Although there were three main Crusades, the conflict between the Crusaders and the Saracens generated almost continuous warfare that lasted the whole of the 12th Century. This produced, throughout the century, a constant traffic of military forces between Europe and the Levant. The Crusaders experienced first hand developments in siege warfare and in fortification that they took back and applied in their own countries.

In essence, there were three ways of forcing entry into a castle. One could climb over its walls, one could knock those walls down or one could tunnel under them! The Crusaders gained ample experience of all three methods, particularly in the spectacular sieges of the First and Third Crusades (Antioch in 1097-8, Jerusalem in 1099 and Acre in 1189-92).

The simplest way of climbing over a castle wall was to scale it using a ladder. It was also the most hazardous method since the scaling ladder afforded the attacker no protection against whatever missiles the garrison might hurl at him. The deadliest of these missiles was the crossbow bolt (or quarrel). Heavier than the usual arrow, it was delivered with far greater force and had a greater range since it was propelled by mechanical energy rather than by the strength of a man's arm. The wounds the crossbow inflicted were so severe that it was outlawed as a barbarous invention by the Lateran Council of 1139. Needless to say, no army would foreswear such a splendid weapon and it continued in use until the 16th Century, when the development of firearms rendered it obsolete.

Yet, the crossbow was a cumbersome weapon, being slow to load. On the battlefield, it was outclassed by the longbow; a trained longbowman being able to fire 4 or 5 arrows to a single bolt from the crossbowman. Behind fortifications, where its user had time to load and was protected while doing so, the crossbow proved to be an ideal weapon. Providing for the crossbow was, as we shall see later, to have a significant influence on certain aspect of castle design.

A better means of scaling a castle's walls was afforded by the siege tower (or belfry). This was a large timber tower, of several storeys, covered with raw hides (to protect it gainst missiles and fire) and mounted on wheels or rollers. Inside it was fitted with ladders and also, on the top storey, with a drawbridge or platform which could be raised and lowered. Apertures were provided in its hide walls for archers. It would be manoeuvred into position close to the castle wall (this invariably involved filling in the castle ditch). The archers inside it would seek to drive the defenders from the wall with a hail of arrows. When it was judged that the defense was sufficiently weakened, the drawbridge would be let down onto the battlements and the attackers would rush the wall walk. A constant stream of attackers could be fed up the tower and on to the wall to maintain the momentum of the attack. Records of major sieges of the period mention the besiegers availing themselves of several such towers. It was not uncommon for the defenders also to build siege towers to directly oppose those of the attackers.

To batter down a castle's walls, the besiegers had the Medieval equivalent of "artillery". This can be broadly divided into two groups of siege engines; the petrariae or stone throwing engines and the ballistae or catapults which fired long iron bolts or javelins. The former were for use against the fabric of the castle whilst the latter were, in modern jargon, anti-personnel weapons. The petrariae can be further subdivided into two groups; the mangonel for throwing smaller stones using the principle of torsion for its energy and the trebuchet which could hurl very large stones or rocks and which operated on the principle of counterpoised weights. The ballista was a giant crossbow.

Crude as these engines may seem to us, they were capable of inflicting considerable damage and loss. At the siege of Acre, King Louis of France had a petraria - nicknamed Malvoisin or "Bad Neighbour "- which succeeded in demolishing a long section of the city wall. Not to be outdone, his ally, Richard the Lionheart, King of England, deployed an engine which killed twelve men with one shot!

However, accounts of Medieval sieges make it very clear that the most effective means of capturing a castle, other than starving it into surrender which could take a long time, was by sapping and mining. Sapping involved attacking the base of a wall or the corner of a keep or tower to dislodge the lower courses of stone so causing the wall above to collapse. This was done either by using a battering ram or by gangs of men using crowbars; both operations being conducted under the protection of a movable penthouse (or cat) which was a large timber shed, again covered with hides and mounted on wheels. Groups of archers would be positioned close by, behind mantlets (wooden screens) to give covering fire.

Mining required the digging of a tunnel below the foundations of the castle wall. Once these were reached, a large chamber was created underneath the foundations by excavating the soil; the wall above being temporarily supported by wooden props. Between these props the miners placed combustible material. Once the chamber was deemed to be sufficiently large, the combustible material was set on fire and the miners withdrew. The supporting props eventually burned through and the wall collapsed into the chamber. At this point, the attackers would rush the resulting breach in the castle wall. It is evident from contemporary accounts that mining was very much feared by the beseiged. Once a mine was begun, the only defence against it was counter-mining; i.e. the defenders would dig their own tunnel hoping to break in to that of the beseigers and halt its construction. To prevent mining, a castle required a wide and deep moat.

Evidence of a successful mining operation is to be found at Rochester Castle, Kent (photo at right). Its splendid Norman keep was originally built with four square angle turrets. In 1215, the castle was beseiged by forces under the direct command of King John. The last part of the castle to surrender was the keep. Its fall was due in large part to the King's miners who successfully mined the South-East angle turret causing its complete collapse. The keep was later repaired but with a round S.E. turret in place of the original square one.

The Crusaders brought back to Europe many improvements in siegecraft and in castle design. One of the most important is hinted at in the replacement of the square by the round angle turret at Rochester. The rectangular keeps and towers that had been built in England during the 11th and 12th Centuries had the great disadvantage of presenting vulnerable corners to the crowbar and the battering ram. Not only were the corner stones easier to remove than those in a flat wall but the corner sheltered the attacker, limiting attacks on him to one direction only. The answer lay with the round tower or keep. The change from rectangular to cylindrical keeps begins in England in the later 12th Century. The transition is by no means immediate and there are several versions of the polyganol keep, that is a tower having many sides but presenting no sharp angles to invite attack.

A fine example is at Orford in Suffolk (photo at left) which, while cylindrical inside, has three large rectangular buttresses on the outside. Other instances of polygonal keeps in the South-East of England are to be found at Chilham in Kent (octagonal) and Odiham in Hampshire (also octagonal and much ruined). Further afield is the magnificent keep at Conisborough in Yorkshire. This consists of a massive cylinder of stone 95 feet high, to which are attached wedge shaped buttresses, spaced equidistant around the outer wall of the cylinder.

Purely round keeps begin to appear in the early 13th Century but are largely confined to Wales and Scotland, very few examples being found in England. The main reason for this was that the impetus to build new castles was much greater in the disputed border regions between England and Wales and England and Scotland.

Other means of defending the base of a wall that made their appearance at this time were the batter or spur and timber hoardings. The batter or spur involved splaying the stonework out from the base of the wall to a considerable breath and depth to frustrate the sapper or battering ram. Timber hoardings were wooden galleries projecting out from the battlements and overhanging the base of the wall. They had appertures in their floors to enable the defenders to drop missiles on the attackers below. The hoardings were the fore runners of machicolations, which we shall meet later.

Finally, the early 13th Century saw improvements in the defenses of the battlements to make better use of the crossbow. The crenallation was improved by increasing the number of embrasures and narrowing the merlons. At the same time arrow slits were incorporated into the merlons so that the bowman could fire whilst remaining under cover.

Significant as these improvements were, there was one which was to lead eventually to a fundamental rethinking in castle design and the obsolescence of the keep. This was the adoption of the flanking tower which developed from concerns about the defense of the bailey. The Anglo-Norman keep and bailey castle was not an integrated design. It consisted of two units, the keep and the bailey, neither of which was able to add to the defense of the other. Moreover, the emphasis in these castles on defending the keep tended to leave the bailey less well protected. Yet the bailey contained many important buildings and much of the castle's supplies. By the end of the 12th Century military engineers were using their experiences in the Crusades to give the bailey added protection and this was provided by the mural or flanking tower. A flat, continuous wall round the bailey was a poor defense. Once an attacker crossed the outer ditch and assailed the base of the wall, the only way the defender could prevent the attacker from sapping or battering the wall base was by leaning over the battlements, thus exposing himself to the fire of the attackers' siege engines and archers.

Towers built at intervals along , and projecting, beyond the outer face of the wall enabled the defenders to enfilade the wall while themselves remaining under cover behind the battlements of the flanking tower. Also, if the flanking tower were built higher than the wall, it commanded the wall battlements. Should the enemy attempt an assault with scaling ladders or belfries, he would face fire from several directions instead of just one. The flanking towers could be turned into strongpoints, dividing the wall into sections, so that the capture of one section of the wall did not inevitably mean the loss of the whole bailey. One of the earliest examples of the systematic employment of mural towers can be seen at Dover Castle, Kent. Henry II built a new (now the inner) bailey at Dover during the last quarter of the 12th Century. This work was continued by John and the inner bailey at Dover was ultimately defended by fourteen flanking towers (including gate towers). Framlingham Castle in Suffolk acquired thirteen flanking towers when its bailey defenses were rebuilt around 1200 by Roger Bigod, Earl of Norfolk.

During the 13th Century the focus of military engineers was to shift more and more towards integrating walls with flanking towers (which became predominantly round rather than square) into cohesive designs in which the need for a keep disappeared. This new thinking was, ultimately ,to lead to the finest expression of Medieval military architecture; the concentric castle .

The English Medieval Castle, Part #1
The English Medieval Castle, Part #2


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