The successful invasion and subjugation of Saxon England in the mid-11th century, by what was to become the ruling Norman elite, led to the construction of hundreds of defensive wooden towers and stockaded perimeters, such as at Carisbrooke, by which the new rulers imposed their control over the country. Such motte and bailey castles, often entirely wooden, comprised a hall and watchtower surrounded by a defensive crenellated palisade and fighting platform on a substantial mound, usually artificial. This was connected by a defensible bridge to a bailey, a palisaded enclosure below the mound
.
Motte and bailey castle building peaked during the struggle for the crown between
the Empress Matilda and Stephen of Blois from 1135 to 1153. The chaos encouraged
both factions, uncommitted landowners and even ecclesiastical authorities, to
construct fortifications.
With the Treaty of Winchester the conflict was resolved and Matilda’s son,
Henry, ascended the throne in the following year. As part of his campaign to
restore and increase effective centralised royal authority, Henry outlawed and
slighted almost a thousand of the many castles constructed without royal licence.
According to Roger of Howden, Henry "took every castle of England into
his hands, and removing the castellans of the earls and barons, put in his own
custodians …". This campaign was perhaps concluded after Henry crushed
the 1173-4 rebellions.
However, castles were not only defensive fortifications designed to impress
other lords and overawe local inhabitants. They also symbolised the prestige,
dignity, wealth and power of their owners. For example, strategically-sited
royal castles, such as Orford, exercised the king’s control over civil
law, maintained public order and countered nearby private castles, like Roger
Bigod’s Framlingham.
The king’s success assisted urban growth in the latter half of the 12th
century with, for example, seigneural investment in planned villages in northern
England, while peace was maintained by the enforcement of the royal writ. His
castles were designed to shift the balance of power from the magnates towards
the crown.
Alongside the king’s peace, the price of luxury goods and staples increased
between 1180 and 1220 as the nobility competed for prestige and social standing
through increased ostentatious consumption. This inflation, combined with bad
harvests and greater royal financial demands, encouraged aristocrats to take
previously rented estates under their own management. Investment and efficient
administration, together with marriage dowries, raised income but required more
resources to be devoted to estate management and the employment of clerks in
the lord’s household. However, the cost of building castles of the latest
design together with providing a sufficient garrison and a retinue commensurate
with the lord’s prestige outstripped the enhanced resources of smaller
landowners who had previously maintained wooden fortresses.
Unlike most motte and bailey castles, new castles were stone built and experimented
with the latest military design. They were more able to withstand attack and
substantially raised the technological level and cost of military works. Increased
cost of construction and maintenance forced lesser barons to drop out of military
competition with the king, even if they had royal licence to build a castle.
Furthermore, the defensive inadequacies of wooden motte and bailey fortresses
were well known to potential attackers and they ceased to be effective defences
and consequently less prestigious. Instead, lesser landowners had to be content
with fortified manor houses, secure against raids, but unable to withstand the
king’s siege train and routiers, mercenary soldiers from Flanders specially
trained, equipped and maintained by the king. The wealthiest magnates, however,
continued, under watchful royal licence, to match the king’s building programme
in order to display their resources, high prestige and ability to undertake
independent warfare.
Castles, especially those of the king, fulfilled an important economic function
and were the most visible part of a complex system. Each was inseparable from
its dependent area, the castellaria. This comprised the castle itself, land
it controlled and administered, feudal duties of surrounding villages and lesser
nobility, its function as a gathering centre for taxation and as the local court.
The network of royal castles also acted as residences for the peripatetic court,
moving from place to place administering government and justice, collecting
rents and consuming the taxation in kind from each region. Others fulfilled
more personal social functions such as bases for hunting parties in the royal
forests of central and southern England. Each was an economically self-sufficient
unit, as Stamford Castle with its corn-drying kilns, bake-ovens and wine cellar
illustrates.
Thus the primary social factors that influenced developments in castle design
were the demand for increased accommodation for enlarged households, their role
as administrative centres of private estates or royal jurisdictions and the
need to boast in stonework the lord’s power, prestige, ostentatious consumption
and potential for warfare, even if the castle itself was incapable of withstanding
a siege.
Contemporary with these social influences, the latter part of the 12th century
witnessed a rapid improvement in military technology which also influenced castle
design. The most significant, as previously noted, was the use of stone in construction.
The greatest innovation in personal weaponry was the crossbow which, despite
being banned for use against fellow Christians by the Lateran Council of 1139,
was too effective a weapon to be ignored and was widely employed by the end
of the 12th century. The alternative short bow had only a limited range, while
the Welsh longbow was not yet in common use in England.
Although expensive, complex, slow to load and cumbersome to fire compared with
the short bow, the crossbow’s bolt could be fired about 370 metres with
remarkable accuracy. This made it a valuable personal weapon for both attack
and defence. The crossbow outranged the short bow and the velocity of its metal-headed
bolt was sufficient to penetrate some forms of armour. In skilled hands and
perhaps with a second weapon being reloaded by an apprentice while the first
was fired, the crossbow’s range and effectiveness meant attackers could
pick off defenders high on a curtain wall or tower and allowed defenders to
hold attacking troops at a distance.
Attacking crossbowmen sheltered behind mantlets, moveable wooden screening which
reproduced battlements and the arrow slits that were beginning to appear in
castle walls. Any opening in the outer wall of a keep, tower or curtain, however,
provided potential access for attackers and a structural weak point less able
to withstand missiles. Narrow slits, introduced to provide light and ventilation,
were enlarged to allow defensive archery fire. Unenlarged light slits through
ten-foot thick walls, by contrast, were impossible to aim through. Their advantages
outweighed their drawbacks as castle technology developed and loopholes became
more sophisticated, providing the defender with a greater arc of fire and personal
protection, such as those in the curtain wall at Pembroke.
The logical development was the provision of several loopholes opening from
a gallery within a tower or curtain. At Dover Castle the original entrance to
the inner bailey was closed by a revolutionary structure, the Avranches Tower,
designed to maximise defensive crossbow fire and attributed to Maurice the Engineer,
working between 1185 and 1190. The slits’ construction provided convenient
ledges to support the forward end of the crossbow stock. This steadied the weapon
and assisted aiming. The tower comprises five faces of an octagon, each with
up to six slits. Two vaulted galleries, one above the other, circle the tower
linking each fighting position which in turn covers up to three slits. The curtain
wall continuing to the north-west is also provided with loopholes. Taken together,
these slits could have "poured a withering fire on any attackers of the
old entrance to the castle" as well as providing enfilading fire to secure
the base of adjoining curtain walls from attack.
The other major development in missile warfare which encouraged innovatory defensive
architecture was the increased accuracy and reliability of siege weapons.
Ballistas were essentially giant crossbows using tensioned rope as a spring
to fire bolts. Mangonels were torsion weapons that could fire stones weighing
up to five hundredweight, although as they relied on rope, which stretched,
they were inaccurate. Trebuchet, which replaced them in this period, were counterpoise
weapons using a substantial weight at one end of a lever to launch stone ammunition.
As the counterweight provided a consistent force, the trebuchet could accurately
deliver repeated blows to the same selected point on a curtain wall. The objective
was structural failure of a castle’s defences at one point.
These developments in missile warfare complemented increasingly professional
siege techniques. Once a castle was surrounded and isolated from a food supply
or military relief, the besiegers could use fire to destroy wooden gates and
hoardings as well as mining to destabilise foundations and bring down a section
of wall. The breach could then be exploited by men-at-arms while crossbowmen
and missile weapons came forward to bombard the castle’s interior. In addition,
if the approach was prepared, belfries could be used by attackers to directly
assault the wall tops.
The inherent weakness of square Norman stone keeps, despite their height and
entrances at first or second floor level, was recognised by the latter part
of the 12th century and was subsequently demonstrated during the siege of Rochester
in 1215. One rectangular corner tower was undermined and part of two walls brought
down with it. Enfilading fire from the curtain wall would be at an acute angle
and therefore less effective. A corner, even if protected by a projecting plinth
and strengthened by vertical pilasters, presented two faces from which an attacking
mason could lever supporting stones. In addition, as at Rochester, if the corner
was undercut by a mine, two faces of the keep’s wall were damaged. When
reconstructed, Rochester received a circular tower at the damaged corner.
Square keeps continued to be built, however, where potential enemies lacked
the resources and expertise for technically-advanced siege warfare. Trim Castle,
Co. Meath, for example, at this period was a rectangular structure with four
corner towers to enfilade the walls.
The design of circular and polygonal stone keeps, for example that of Pembroke,
built c.1200 and Conisborough, had already attempted to overcome the square
keep’s vulnerability to masons attacking the "dead ground" at
the corners. The angled walls were also designed to deflect siege engine missiles.
The height provided vantage points and an elevated platform roof from which
defenders could hurl missiles down. Battered plinths, such as those at Conisborough’s
keep, allowed missiles to be ricocheted horizontally into attackers’ faces
and helped keep siege towers at a distance.
However, the pressure to provide increased accommodation to cater for castles’
developing administrative roles together with the vulnerability of keeps to
more effective siege engines and mining techniques, essentially rendered such
towers obsolete as the primary defensive structure.
Instead, designers turned to experience gained in the crusades. They moved the
zone at which an attacker was confronted outwards from the keep to the surrounding
curtain wall. This is illustrated by the second phase of construction at Carrickfergus
between 1216-23. In this way the defensive strength of the structure was "redistributed
and multiplied to a series of strong points comprising towers built along the
circuit of the curtain wall", instead of restricted to a single massive
tower. Platt regards Conisborough’s curtain wall as especially innovatory
with its solid half-round towers. Even if the intervening wall were captured,
each tower could, in theory, become a separate defensible cell overlooking the
wall walk and able to rake attackers with missiles.
Mural towers, initially rectangular but soon built circular or polygonal, transformed
weak spots in the defence, such as entrances and corners, into strong points.
It is possible that then extant remains in the Mediterranean of classical Roman
castrum provided the initial inspiration for crusader castles such as Belvoir,
built for the Hospitallers after 1168 and Krak des Chevaliers. Barons and their
masons returning from the crusades probably brought these ideas with them.
Mural tower roofs provided fighting positions from which enfilading fire could
be provided to cover the connecting curtain wall and ditch as well as platforms
from which defenders could operate large missile weapons. Together with the
curtain wall battlements, tower roofs became the principal points of defence.
Passages within the walls allowed soldiers to move around without obstructing
the fighting platforms as, in a siege, the hall and other rooms were full of
stores. Such internal passages, lit by slits in the wall, may have inspired
the crossbowmen’s fighting galleries at Dover Castle.
A further innovation was stone corbelling and slots near the top of the curtain
and mural towers to support temporary wooden hoards from which archers and men-at
arms could launch missiles. These were, however, vulnerable to siege engine
missiles and to fire and were gradually replaced at key points, during the thirteenth
century, by stonework machicolations. Hoardings and machicolations allowed defenders
to drop missiles on attackers at the wall base and dump water on fires placed
against wooden gates.
With defensive strength concentrated on the curtain walls and mural towers some
castles, such as Framlingham, apparently dispensed with the keep altogether.
The castle resembles a wooden palisade recreated in stone with the new-fangled
mural towers added to give the owner greater prestige. However they were perhaps
more for show than defence, they project so little that they fail to protect
the curtain and would be of little use in a siege.
The logical development of curtain wall defence was the provision of several
concentric wall-and-tower circuits, each higher than the one outside it, enclosing
a series of separate defensible baileys. At Dover, for example, although Henry
II favoured a square-designed keep, the most convenient for accommodation, the
principal defensive strength comprised two concentric curtain walls equipped
with rectangular mural towers and strong gateways. When besieged by the Capetian
Dauphin, Prince Louis, in 1216 Dover’s wall and tower system was too strong
for the besiegers and the keep was never threatened.
Concentric defence could only be used where there was sufficient room on the
site to permit it and the resources of the builder could meet the immense cost
of the work.
Henry II’s son, Richard I, spared no expense to provide three successive
lines of defence at his "Fair Castle of the Rock", Château-Gaillard
on the Seine at Les Andelys, built 1196-8. An important aspect of concentric
defence, illustrated at Château-Gaillard, was that each wall and drum
tower "circle" was constructed higher than that outside it and that
the keep at the centre was the highest point of all . This allowed the fighting
platform at the top of each wall and tower to be overlooked from inner walls
or the keep. In addition, the inner parapet of each fighting platform was kept
low. In this way, if the outer curtain was captured by besiegers, the defenders
of the inner curtain still had the height advantage and the besiegers lacked
stonework to shelter behind.
Approachable only from the south-east, Château-Gaillard was invested by
the French king, Philip Augustus, in 1203. The besiegers methodically broke
through the outer ward and secured the middle ward through a small group climbing
the precipitous western slopes and gaining access through the crypt and chapel
added by King John in 1202. The defenders withdrew into the inner ward which,
overshadowed by the keep, provided an even tougher defensive position. Inevitably
there was a weak point. The bridge linking the inner and middle baileys provided
cover for sappers to mine the wall and although intercepted by countermining
they weakened the inner bailey curtain. Siege artillery then bombarded the wall.
As the final attack was made, the 140 remaining defenders surrendered rather
than retreat further and fight from the keep alone.
Some aspects of Château-Gaillard were less innovatory. Wooden hoarding,
for example, was still used, perhaps because stone machicolations, which Richard
must have observed in the Near East, were never completed. Also, although crossbows
were in common use there appears to be no special fighting positions for them
within the walls and towers, as at Dover Castle for example. They seem to have
been restricted to the battlements.
The range of siege engines and crossbows, together with the threat of mining
also prompted the digging of encircling moats to keep attackers at a distance
and flood underground workings. A moat had to be filled with fascines before
attackers could reach the base of a castle. Even a shallow wadeable depth would
slow any assault and prevent the use of belfries or battering rams. However,
moats were unsuitable for hilltop sites or on porous rock and were almost as
expensive to build as a circuit of concentric defence.
These improvements in the bailey’s defences speeded the keep’s obsolescence
as a defensive structure and it was only retained for accommodation. Instead,
the latter part of the 13th century, beyond this period, saw gateway-keep entrances
become the most powerful defensive element, as illustrated by the Welsh castles
of Edward I.
Castles fulfilled a variety of functions. To be effective symbols of wealth,
influence and warlike ability they had to impress other castle owners and consequently
exhibit credible forms of defence. Between 1175 and 1225 military engineering
adopted a more scientific approach based on armour-penetrating enfilading fire
of crossbowmen stationed in towers. Castle design advanced from defence to offence,
from square keeps to concentric walls and towers able to withstand missile attack
and mount substantial counter-battery firepower of their own. Those aspiring
to military strength and influence, of necessity, had to maintain their position
in this arms race and incorporate at least some of these innovatory elements
into their buildings.
As they evolved into administrative centres of vast estates and provided impressive evidence of their owners’ high social standing, castles of the early Angevin period came to epitomise the fusion of social and military functions of the Norman elite. Fortress and country house, local court and hunting lodge, social change and military innovation combined to produce new design complexity to these statements in stone, graphically illustrating both the bellicose independence and prestigious landholding status and wealth of the lords that built them.
Works referred to:
Brown, R. A., 1976, English Castles, London
Dyer, C., 1989, Standards of Living in the Later Middle Ages, Social Change in England c. 1200-1520, Cambridge
Fry, P. S., 1974, British Medieval Castles, Newton Abbot, David & Charles
Johnson, P., 1978, The National Trust Book of British Castles, London
King, D. J. C., 1988, The Castle in England and Wales, An Interpretative History, London
Mallory, J. P., and McNeill, T. E., 1991, The Archaeology of Ulster from Colonization to Plantation, Belfast.
Platt, C., 1978, Medieval England, A Social History and Archaeology from the Conquest to AD 1600, London
Platt, C., 1982, The Castle in Medieval England and Wales, London
Platt, C., 1990, The Architecture of Medieval Britain, A Social History, London
Renn, D. F., 1969, "The Avranches Traverse at Dover Castle", Archaeologia Cantiana 84, pp 79-92.
Simpson, W. D., 1949, Castles from the Air, London
Simpson, W. D., 1957, Exploring Castles, London
Steane, J., 1985, The Archaeology of Medieval England and Wales, London
Warner, P., 1971, The Medieval Castle, Life in a fortress in peace and war, London