Ignacio-Javier Gil-Crespo

reinforcing chains in Spanish Medieval fortifieations

Ig'' ,cio-Javier Gil-Crespo

psearch Center "José Joaquín de Mora"-Cárdenas Foundation

nc walls of castlcs and Fortrcsses havc always playcd a key rolc: they had to resist not only mechanical aciions, bu[ also attacks with projectilcs and battcring rnms. And so, to make thein able to withstand attacks irom ,,ncmies' walls had lo bc rcinforccd with interna1 woodcn chains. This reinforcement also scrved to stabilisc Ihe walls i t i the cvcnt of a breach occurring, prcvcnting thcm from collapsíng and facilitating their fast reconstruction. f i e wooden reinforcing mcthods followed woiild be di*, dcpending on thc technique uscd by builders to constru~i ihe walls. In rammed earth, fomwork or masonry walls, bmnches and beams are laid insidc the earth or thc lime and mbhlc. In stone masonry walls and aslilar or brick walls, the wooden beams reinforce the interna1 fifling. Auihom such as Vitmvius or Philon of Byzantium had already referred to this poliorcetic building lcchniquc in ancient times. Tliey m m m e n d e d the usc of wooden beams inside the walls to reinforce them; and ii was during tlic Middlc Ages tliat lhcir recommendations were followed and fully applied.

Gowadays, we can still visit some Spanish Medieval fortifications in which the wooden reinforcement is clearly fisible. The ruination of castles often reveals the building 'section' of the walls, and so, we can see the einforcing system, study it and trace it. Usiially, wood has rotted and fallen away through with time, and the only

thing that remains is the irnprint il has IcR on the wall mass. Despite this loss, there are some cases in which wood itself has been presewed, or thc reinforcement design can be recorded.

Reinforced Walls Building Tradition: from Babylon to Medieval Europe

Commonly, walls are not just built with masonry or "hard" materials, but they are frequently reinforced with vcgetable fibres: straw, branches or wooden square beams. The first aim of this reinforcement systcm was to help supprt the bricks and avoid s h i h and movements while thc mortar drid, and lo makc rhe wall one single unit but with a ccrtain amount of elasticity, allowing the wall enough flexibility to scttle witlioul cracking.

However, it is onc thing to improve the structurat behaviour of masonry walls and conwol B e movemenis and shifting due to h e drying orrnortar, thc rcinforccmcnt of the walls using wooden chains embcdded in Uie nibblc or the masonry is difícrent. Jn this case, the oim is dien (also) to make the wall able to withstand cxtcmal actions,

the attack of a battering ram during a siege, for example.

wall reinforcement using wooden ties is an ancient constmction practice. Ln Myccnaean f~i t i f ¡~at ion~ some Wooden beams were embedded in the wall mass, giving thc curiain wall "une sorte d'ossaíurc" made by builders embedding transversal and longitudinal timbcr in ihe walls at dil'fcrent heights.[l] Wootlcn reinrorccrnents were

Wooden reinforcing chains in Spanish Medieval fortiJications 7 used in ancient Greek architeclure, although not systeinatically, to increase the resistance of tlie walls again battering of a rain and to reinrorce tlie brick or aslilar iniisonries. [2]

the

Gaulish cities were surrounded by walls built with stoiie and earili inasonry bonded by liniber lies. 1" fa,.( , passage in Caesar's De Bello Gallico (Book 7 , ~aragraph 23), dcsciibes tlie wall constnictioii iechniqu~ of

1c Gauls and adds: "it possesses great advantages as regards iilility and tlie dcfcncc of cities; h r tlle stonc protects

i t froin fire, and tlie wood froin the battering rain, since i t [tlie wood] being morlised in thc inside witli r o w

O f beains, generally forty feet each in length, can neither be brnkeii tlirough nor (orn asiindcr".

Ancient Grecks snd Roinans leaint froin (Iieir conquests. Lhcy studicd other pcoplc's constriiciions and developed Ihc science of tlie polioi-ceiics and Fortific~tion. Philon of Ily~anliuin wmtc his ircatise on r ~ r l i f i ~ a t i ~ n s and in it he oMered some rccommendations on tlic planning of fonrcsses, ihe naturc of ihe ground nnlo which to build ihcse fortresaes and thc size, form, clenicnls and inatcrials lo be uscd in (he constniction of the walls so as to mnkc tliem strong eiiough to stand a sicgc and to rcpcl sn attack of the enemy. He also recoinmended the face op the walls be built with stones or stones with salient bosses in the most exposed areas in view of an attack with siege engines: "timber ties of oak should be buried in the walls of both curtains and towers, the timber being placed end to end and forming horizontal chains at vertical intervals of 6 ft. The presence of these ties greatly facilitates the repair of any part of the wall which may be damagedU.[3]

In Vitruvius's De Architectura Libri Decem (Book 1 , chapter 5) we find some recommendations about the choice of the best place to build a city and the form, size and reinforcements needed in order to guarantee the solidness and strength of the defensive walls. Amongst other building items, Vitruvius suggests putting some charred olive wood "binding the two faces of the wall together like pins, to give it lasting endurance". For Vitruvius, olive wood is an almost ever-lasting material, which even when buried in the earth or immersed in water neither decays nor weathers and remains sound and useful. Notwithstanding the authority of Vitruvius, in the Spanish translation of his work made by Joseph Ortiz in 1787 an additional recommendation is given: "it will be a ver - dangerous mistake to put such long beams, with their extremes in the outer sides of the walls, as someone has drawn because they will be exposed to fire and surely collapse".

Byzantine builders learnt about the various aims of reinforced masonry (stone and brick) fioin Ancient Babylon and classical poliorcetics. First, the inserlion of wooden chains allows for the stabilisation of the building during the first stages of construction, especially during the drying of the mortar. Second, this reinforceinent balanced forces and trusses improving the seismic behaviour of the walls, arches and vaults. And Lhird, the wooden chains reinforced the walls where externa1 actions (such as warfare, the beating of the sea ...) were worse. This is the case, for example, of the monastery of Prinkipo (6-8th centuries), where there is an oak structure of 20x20 cm square beams that have been embedded in the morlar of the wall, at five regular intervals. Also the lurrets of the walls of Constantinople were reinforced with wooden beams laid inside a brick sti.ucture.[4]

Commonly, Byzantine fortresses were built with a facing of stone and brick and a core of mortared rubble. To join the two materials and to keep them together, a system of wooden beams was usually set, a system which is still visible in Metabloe, Selifer, Susurkuk, the tower of tsaak Angelos in Constantinople and the castles of Achyraous and Lopadion built by the Kommeni.[S]

The works on construction and poliorcetics written by ancient authors such as Vitruvius, Vegetius and Philon of Byzantium became well known and highly respected by Medieval builders, especially since the 13"' century. For

Ignacio-Javier Gil- Crespo

instarice, Ainaury de Moiitfort built the castle of ~~~d~~ (Seine-et-Oise) betweeii the years 1105 aiid 1137 foliowing Vitr~iviiis's recoiuineiidatioiis on the layout of the keep, or Vegetiusls ideas on tiie flanking towers biiilt in the walls.[6] Ttie descendants of Guillaulne l e Conquérant, the Plantagenet, dukes of Norinaiidy, built inost of tlie French castles in the 12'" century. Guillaume le ~ ~ ~ x , son of Guillaiiriie le Conquéraiit, ordered tlie construction of tiie castle of Gisors (Eure). The builder was R0beí-t de Bell61iie. Tlie castie is located on al1 artificial inouiid 20 in high and it has a keep (20 in high and 25 m in diaineter) and a siirrounding cliernise (70 in in diameter).[7] "A nurnber of wooden beains are bedded in the rubble of the cliernise to reinforce the cernenting of the masonry; this also follows tlie principles recommended by Vitruvius (1, 5) and Philon of Byzantiuin (3, 3)".[8]

During the restoration works, Viollet-le-Duc observed lhat the walls of the castle of Coucy were built with a wooden chain in their interna1 part: "toute la inaconnerie était chainée au moyen de longrines de bois de 0,20 a 0,30 in d'équarrissage, noyées dans I'épaisseur des murs, suivant la inéthode encore en usage pendant le XIIe sikcle. Au-dessus de la vohte du preinier étage, ce chainage se reliait i une enrayure égaleinent en boisU.[9] Following Viollet, Choisy poinled out that "its use goes back to the most distant Ancient times, and it was for the saine reasons: to distribute the effect of impacts during attacks".[lO] The castle of Verclause was built around the year 1220 (experts have been able to date it using dendrochronology). A wooden chain with pieces 20-30 cm of section and joined together was laid inside the masonry. The chain was set at at least three different heights in the tower with bow-plan.[l 11

Wooden Reinforcernent in Spanish Medieval Castles

In the Middle Ages, from the 8"' to the ls th centuries, the Crowns of Castile and Aragon were continuously enlarging their tei~itories while re-conquering areas that belonged to the Muslim realms. And between the 1 2 ~ ~ and 1 5 ' ~ centuries they were also fighting amongst themselves. Therefore, we can define this period as a latent state of war. Throughout these 800 years, nuinerous defensive constructions were built: watchtowers, city walls, castles, fortresses, fortified churches ... Building techniques were various and some of them were in use for a long time while others were only specific to particular periods. For instante, stone masonry walls were built in every single period and always following, more or less, the same building principles, while fonnwork inasonry is apparently specific to the 1 2 ' ~ and 1 3 ' ~ centuries, and rammed earth was mainly used in the palace-castles of the 1 4 ' ~ and 1 5th centuries. This is the general rule; and of course there are exceptions to that rule. Rammed earth had been in use since the loth-1 llh cenluries and, very soon, builders learnt to use it to reinforce weak points in the walls, such as corners, that were usually built with stone inasonry but without any ties. Many walls lost verticalily and so builders began to put some wooden ties in the corners, as it can be seen in the castles o i Autol, Arnedillo and Clavijo (La Rioja).[l2]

Nevertheless, there is a construction invariant in al1 of these building techniques: walls were usually reinforced with wooden branches or beams embedded in the masonry, the rubble or the rammed earth. In soine cases, these branches were only laid along the wall and in other cases a wooden chain was designed and built. The use of wooden chains was not only to horizontally reinforce and strengthen the wall, but they were also bracing systems Lo support turrets or echaugettes or to join corners and construction joints (Le. between different materials).

The castle of Soliedra (Soria) was built on an ancient Muslim fortress -whose foundations still remain- and was still in use during the war between the Infante Alfonso de la Cerda and the Crown of Castile at the end of the 12th century: the Infante asserted his title to the Crown of Castile. Later on, the castle was intentionally destro~ed. The building technique used in this castle was stone facing masonry filled with rubble. The comers were

Wooden reinforcing chains in Spanish Medieval fort@ations

reinforced by laying various layers of wooden beams which are still visible today. There are four or five horizontal beains in each layer and, finally, two intervals of ~ h ~ i n s in the reinaining sections of tlie tower (Fig. 1).

Figure 1. Wooden beams bedded in the rubble of the walls of the castle of Soliedra

Castles built with formwork masonry. 1 l'h-13'h centuries

With the conquest of Toledo in 1085 by King Alfonso VI, the Crown of Castile enlarged significantly its territov. Therefore, at this time many new towns and cities were built in the newly acquired territory so as to control -demographically, militarily and economically- the extremaduras (the southern bordering territories of the Christian kingdoms); new city walls, Romanesque churches and fortresses were also built. One of the most used building techniques was formwork masonry. This kind of technique allows express construction, durability and resistance against siege warfare, employing vernacular materials without needing to use previous and specialized works (as is the case with ashlar masonry).

Moreover, during the and 13' centuries, the Crown of Castile was at war in different borders of the Iberian Peninsula. First, between the years 11 18 and 1 124 the Crown of Aragon conquered the Ebro valley and bumped into Castilian borders in the area that is today the province of Soria. Dynastic quarrels and a lack of definition of the borders ultimately resulted in a long-lasting war between the Crowns of Castile and Aragon until they finally reached peace and were united under one crown by the Catholic Monarchs by the end of the 15" century. Second, in 1157 Alfonso VI1 died and his kingdom was divided into the Crowns of Leon and Castile. In the year 1230 Ferdinand 111, also called Saint Ferdinand, inherited the thrones of Castile and Leon and secured the permanent union of both crowns, but until then several wars were fought and borders had to be fortified and strengthened to withstand the enemies' attacks. Third, the Almoravid and Almohad Islamic Empires became strong in the Mediterranean and the Southern Iberian Peninsula after a period of weakness of the taifa kingdoms. The Battle of Las Navas de Tolosa (1212) allowed Castile to win over the Guadalquivir valley and conquer the cities of Cordoba and Seville. To round up this period in Spanish history, several civil wars occurred in Castile during this time. And throughout al1 this battling and fighting, building activity was strong, many new castles were constructed and the ancient ones rebuilt, restored os reinforced.

The complete process to build a wall with foimwork masonry is as follows. The wall is founded on the bedrock. If not, then a stone foundation is built to avoid mines and underground attacks. Next various materials -mbble, pebbles, boulders ... and lime-are poured into a wooden formwork. Once the operation is completed, the box is

Ignacio-Javier Gil-Crespo

s u c c e s ~ i ~ ~ l y moved 10 ihc next StagC. Walls are COiiiinonly 1.80-2.40 m wide. ~ i ~ ~ l l ~ , the last parl of the wall is built, a thicker aiiid ifllemiiitent arca, wliich is wficrc ihe wall-walk and the battlements were built. In the lower pnm of the wall, when thc slope of he ground w0uld noi alIow buildFrs to pul fhe Fomwork in botli races, o n l ~

the boards of the cxlcmal face wem sct and the matcrial was pouwd ngainst the rock; lhat was thc case, for mnmple, of iIle wdls buill in tlie cily of Scgovie.[l31 It was not always ihal the lateral formwork waS crected. and so thc joints itito the "pouring-boxcs" werc sloped. The rammed arth constniction tecliniquc is similar, biil it diffcrs in ihai ilic material is usunlly coinpacied ant! ilie face is a lime-crusted layer.

ln both techniques the only connection between the successive boxes is by friction. Therefore, in order to brace the successive inasonry boxes, it was very cornmon to put wooden ties einbedded in the rubble, in the low parts ,f the walls.

The bordct castles bctwcen Caslile nnd Aragon of Peroniel del Campo and Soria still llave these chains, or their imprint can still be seen. In both LYSW iherc are wooden beams 15x9 cm that were laid horizontally at each constmclion lcvel (Fig. 2). The construction process was as follows: first, the fronts of the fonnwork were set and fiey werc braced using noedles madc witli a couple of thin branches. Builders then tied the vertical timber joining d ~ c boards of he fonnwork. Over he needlcs, ihe wooden chain was then laid to place and support them and, afterward~, the masonry was poured in the box.

Figure 2, Tower of the gate of the castle ofperoniel del Campo, in where the wooden chains has been signed

Structurally speaking, in defensive architecture the main forces are perpendicular to the wall (projectiles, missiles, 'am s...) and they have to be resisted by the width of the wall and the interna1 ties and chains. The friction between two formwork masonry boxes is not always enough to resist the attack of a siege machine or the stones thrown by a kebuchet. This is why there is a wooden chain in the externa1 border of the rubble. The medieval castle of Soria Was demolished in the year 1813 -aRer the Peninsular War against the French- using powder and dynamite. The remains of the waIls reveal that the force of the explosions displaced the Medieval formwork masonry boxes horizontally but the wooden chain provided resistance (Fig. 3).

Wooden reinforcing chains in Spanish Medieval fortijkations

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Figure 3. Negative of the wooden tie in the rests of the walls of Soria, after the explosions and demc 1

The castle of Saldaña (Palencia) was built in the.1 lth century and was named after Juan Alfonso de who lived there in the 1 4 ~ century. The building technique usedin this castle was the same, with that in this case the faces were built with ashlar. Each interval of formwork masonry was reinfo rows of wooden chains and, in the lower parts, the beams were connected with ties to the interior o1

4).

Figure 4. Hollow of the wooden chain placed in the rubble of the formworked masonry oflhe castlc visible when externa1 ashlars have disappeared (generally, they have been stolen and reused in 0th constructions)

Ignacio-Javier Gil-Crespo

This systeiii was also einployed iii other defensive biiildings such as the towei of La Pica (Soria) or the castle OS Turégano (Segovia). The inost coinplex reiiiforced systein is that of the exteinal encincture of the castle of ~Urégano. The flanking towers are built with walls of formwork inasonry OS rubble, sinall stones and lime. The towers are filled with rainined earth al1 the way up to the wall-walk and parapet. The low part of soine OS the walls were reiiiforced with woodeii chains OS 20x20 cin sqliare beains over wliich builders added other rectangular beains (abo~it 5x15 cm) that joiii tliein with the interna1 fi11 of rainmed earth. Tliis systein is coinpleted witli other vertical tiinbers (Fig. 5).

Figure 5. Negative laid by the wooden chuins of the turrets of the outer walls of the castle of Turégano

Castles built with rammed earth. 141h and 15lh centuries

After the Civil War OS 1356-1369, also known as the War of the Two Pedros, the crown of Castile passed to the Trastámara Dynasty. They progressively transformed the lands of the Crown (public) into large private estates, on the one hand to free the Crown of the responsibilities of governing and to have a more effective control over the territories; but also to show their gratitude to the various noblemen that had stood by their side and had helped them during the wars. These new estates would see the building of severa1 alcázares or castle-palaces.

Many OS these castles were built using the lime-crusted rammed earth technique. The upper battlement and the parapet walk were built with stone and inortar Sor masonry that protects the top of the rammed earth walls from erosion. Late Medieval Christian Castilian Sortifications have used rammed earth with only dry earth and a mix of earth and lime. The formwork used in these fortresses tends to be continuous, but there are many cases of closed boxes OS formwork in which to ram Lhe earth. Earth is the sole material in most cases, but there are masonries in which it is combined with brick in rows and buttresses.

As for the putlog holes, they tend to be placed in the immediately inferior constrnctive leve1 and formed by the ilnprint of the putlog and placing stones over the beam. This system facilitates the extraction and later reuse OS the beams. They usually have a rectangular section. This putlog systein simplifies the bracing system used in Islamic construction which was based on half-beams, nails, wedges, Saint-Andrew crosses and rows which are

Wooden reinforcing chains in Spanish &fedieval fortz~?cations

abandoned inside the earth. In addition to simplifying the manufacture, the advantage of passant and rectangular putlogs is that they serve as scaffolding and can be reused as the building work progresses. Separation between the axis of the putlog holes tends to be constant in each castle because putlogs were reused constantly along the building construction. [l4]

Another important consh-uctive characteristic of Castilian rammed earth is that there is an interna1 reinforcement system. This system usually consists in a wooden chain that is placed inside tlie eartli at the same time as the earth is rainined. This wooden reinforcement is also used in the corners, where logs are set at 45-degree angles between the two walls that meet at the comer. The ties are also set in the joint of elements with different materials or constructive elements, such as turrets.

The castles of Serón de Nágima (Soria) and Palenzuela (Palencia), although separated by more than 200 km, are similar in both size and typology. They were presumably built at the end of the 14 '~ century or the beginning of the lsih century. Their walls are 2.70 m wide, equivalent to nine Castilian feet. Both castles have a square plan with towers in the comers: two in Serón and three -perhaps four- in Palenzuela. In the case of Serón, part of the north, part of the west and the south walls are preserved, as well as the low part of the southeast tower and part of the southwest tower. Walls have deteriorated immensely and parts of them have even collapsed. In the case of the castle of Palenzuela, the building preserves three of the possibly four comer towers it had and some parts of the curtains in between them.

Some beams of the perimeter wooden chain set along the walls are preserved in Palenzuela. With the collapse of the extemal layer of lime-crusted rammed earth, it is possible to see the wooden chain at every constructive level or, at least, the imprint it left. Branches are placed just undemeath the putlogs, behind the lime-crusted external layer and parallel to the fiont of the wall. The chains seem -the ruins are in bad shape- to be continuous along the walls of the towers and especially in the corners (Fig. 6).

Figure 6. Tower of the castle ofPalenzuela, where the wooden reinforcements of each rammed earth level are visible when the external lime crusted layer has disappeared

Ignacio-Javier Gil-Crespo

In ~ h c collapsed remains ofseriln ii is possible to see thc "sectionM of the waII, and it reveals the use of a couple o f ~ d e n cliains 011 eiicll ~0~SlrUctivc Icvcl: the fírsi is placed on the low part of the ratnrned earth layer and the second is se1 tindeneatli h e pullogs ~f tlie following lcvel (Fig. 7). In addition to these wood eleinents, of wliich

he mce or Ihe iinprini inside [he e~rth remains. 0 t h items have been found einbedded inside the wall. l'hey are wooden mugh 10% aboiit 8 10 10 ctn in dioincter. They appear inainly in iIie corners or in encouiiters ~ ~ t ~ c e n lhe castle walls. l'erhaps Ilicir rolc was to lock the joint behveen perpendicular walls. After the Marcli 201 1 collapse, Come rougli logs llave becn fouiid insidc [he ruins of tlie rainrned eartli and have been collected fol. laboralory andysis. I'lie samc Systcm was iised in ilic castle of Monreal de Ariza (Zaragoza), Aragon's border ca,tlc near Cnsiile ttnd vcry clow to Ser611 (Pig. 8).

Figure 7. Section of the west wall of the castle of Serón de Nágima. First levels have an external layer of ashlars íthey were stolen at the beginning of 20 '~ century) and the upper levels have two wooden chains each one, placed behind the lime crusted external layer

Wooden reinforcing chains in Spanislz Medieval fortiJications

Figure 8. Some wooden beamsplaced inside the rammed earth walls of the castle of Monreal de Ariza

Finally, the castle of Fuentidueña de Tajo, near Madrid, shows the use of wooden ties to brace cantilevered turrets or echaugettes. Despite the information present in the first documents dating from the 121h century, the castle was restored and reused in the uth and 15"' cerituries, when it was property of Don Álvaro de Luna, Constable of Castile. The current remains include a curtain and part of the 14-meter-high keep. The walls were built with rammed earth while the echaugettes were built with brick and stone masonry. In.the inner part of the hedges of the keep there are some wooden pieces that are inside the masonry. The function of these wooden beams is to support and to reinforce the brick masonry of the cantilevered turrets in the keepls comers. There are two systems of wooden ties in, the echaugettes. Firsl, there are some wooden beams placed radially in the turrets. They seem to connect the externa1 face of brick or masoniy to the interna1 rubble. The second system ties the echaugettes to the rammed-earth walls by laying two or three parallel beams at every constructive leve1 (Fig. 9).

\ 1 \

Ignacio-Javier Gil-Crespo

Figure 9. Axonornetric analysis of the wooden ties for the echaugeltes of the castle of Fuentidueña de Tajo

Conclusions

Historical architecture has been reinforced with vegetable fibres to achieve three main goals. The first one is to improve the flexibility of the masonry walls against movements, either seismic or, more commonly, due to mortar drying. The reinforcement of the beds o i mortar between courses of bricks was born in Ancient Mesopotamia and Egypt and it is still been used today in traditional architecture. Ryzantines reinforced their walls also to avoid cracks derived from the lack o i volume when the mortar dries. The second function is to connect several parts of the building so as to distribute stress evenly, ¡.e. vaults and walls, o r t o connect different

Wooden reinforcing chains in Spanish Medieval fortzjications

inaterials or voluines of the buildings as well the external layer with the rubble core of the wall or the cantilevered turrets with the walls. The latter is to give more resistance to the wall against external attacks. Militaiy walls protect a secure enclosure against the external eneinies who want to enter to occupy the city or the fortress by breaching the walls. When the wall is hit by a battering rain or a projectile, the inteimal reinforceinent will distribute the buinp and, in the case of tlie wall collapsing, will avoid the coinplete ruining of the whole building, holding the reinains and facilitating quick reconstruction.

This poliorcetic technique was born in Mycenae and was used by the Greeks and the Roinans (who learnt it also from the Gauls) and it beca~ne generalized during the Middle Ages -by influence of ancient books on architecture written by authors such as Philon of Byzantiuin, Vitruvius or Vegetius- to the point of constituting an accurate "wooden skeleton" for the inasonry. Governors and builders followed their recommendations on the defence of fortresses and cities and used them systematically in every building technique and in every historical period.

References

[l] A. Choisy, Histoire de I'Architecture, Paris: Gauthier-Villars, 1899, vol. 1, pp. 227-228. [2] R. Martin, Manuel d'architecture grecque, Paris: Picard, 1965, vol. 1: p. 32. [3] Cited by: S. Toy, Castles. Their construction and history, New York: Dover, [1939] 1985, pp. 21-22. [4] E. Mamboury, 'Le couvent byzantin de femmes Z1Prinkipo2, Échos d'orient, no. 19 (1 18), 1920, pp. 200-208. [5] C. Foss, 'The defenses of Asia minor against the Turks', Greek Orthodox Thological Review, no. 27, 1982, pp.

145-205. C. Foss, 'Byzantine Malagina and the Lower Sangarius', Anatolian Studies, no. 40, 1990, pp. 161-183.

[6] F. Gébelin, The chhteaux of France, New York: Putnam, 1964, p. 39 [7] J.P. Panouillé, Les chateaux forts dans la France au Moyen Age, Lille-Rennes: Editions Ouest-France, 20 15,

pp. 9-10. [8] Gébelin, Chbteaux, (Note 6 ) p. 44. [9] E.E. Viollet-le-Duc, Essai sur l'architecture militaire au Moyen-bge, Paris: Librairie dtArchitecture de Bance,

1854, p. 98. E.E. Viollet-le-Duc, Description du chhteau de Coucy, Paris: B. Bance, 1857. [lo] Choisy, Histoire (Note 1) p. 717. [ l 11 P. Bernardi, Batir au ~ o ~ e n Age, Paris: CNRS Editons, 201 1, pp. 191 -192. M.P. Estienne, 'Les chainages de

bois du donjon de Verclause (DrBme)' pp. 257-262 in J.M. Poisson, J.J. Schwien (Eds), Le Bois dans le Chiteau de pierre au Moyen Age. Actes du Colloque de Lons-le-Saunier, 23-25 octohre 1997, Besancon: Presses Universitaires Franc-Comtoises, Picard, 2003.

[12] B. Cabañero Subiza, 'Los castillos de La Rioja construidos frente al dominio del Islam. Notas sobre su origen', Cuaderno de invesigación histórica Brocar, no. 19, 1990, pp. 19-40.

[13] E. Herrero García, M.Á. Martin Blanco, 'Hipótesis del sistema constructivo de la muralla de la repoblación cristiana de la ciudad de Segovia', pp. 801-810, in S. Huerta and P. Fuentes (Eds), Actas del Noveno Congreso Nacional y Primer Congreso Internacional Hispanoamericano de Historia de la Construcción, Segovia, 13 - 17 de octubre de 2015, Madrid: Instituto Juan de Herrera, 2015.

[14] I.J. Gil-Crespo, 'Late medieval rammed earth technique in the fortifications of Castile, Spain', pp. 185-192, in B. Browen, D. Friedman, T. Leslie, J. Ochsendorf (Eds), Proceedings of the Fifth International Congress on Construction History, Chicago 3-7 June 201 5, Chicago: Construction History Society of America, 2015.

Purther Studies in the History of Construction

The Proceedings of the Third Annual

Construction History Society Conference

Queens' College, University of Cambridge, 8- 1 O~ April20 16

Edited by

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Nicholas Bill

Michael Driver

Michael Heaton

Yiting Pan

Michael Tutton

Christine Wall

David Yeomans

Published by The Construction History Society 1 Scroope Terrace

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O 20 16, First Edition ISBN 978-0-992875 1-2-1

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Proceedings of the Third Construction History Society Conference edited by James W P Campbell, Nina Baker, Nicholas Bill, Michael Driver, Michael Heaton, Yiting

Pan, Michael Tutton, Christine Wall and David Yeomans