Fortifications and Siege. (11 pts)

[Longmane]

This thread will be concentrating on a chapter taken from the book "WESTERN WARFARE IN THE AGE OF THE CRUSADES 1000 - 1300" by John France.


Pt1

Fortifications and siege

Castles were never the only fortifications in medieval Europe. By the end of the period there were cities everywhere, and most had stone fortifications. Large cities were more common in southern France, Spain, Italy and the Holy Land than in northern Europe.

In Italy, Florence, Milan, Venice and Genoa, and in Spain Cordoba and Granada, all had populations of 50,000-100,000, but in northern Europe only Paris was of this magnitude, although Ghent and Bruges may have approached 50,000. Cities of 25,000–50,000 included Padua, Bologna, Verona, Pavia, Lucca, Rome, Naples and Palermo in Italy, Barcelona and Valencia in Spain, Toulouse in Provence and only Bordeaux, Lyons, Rouen, London and Cologne further north. In the 10,000–25,000 range, Italy had Cremona, Mantua, Modena, Parma, Pavia, Rimini, Forli, Faenza, Ravenna, Cesena, Orvieto, Perugia, Sienna, Pistoia and Pisa, and Spain had Zaragossa, while northern Europe could count Abbeville, Amiens, Arras, Lille, Ypres, Douai, Valenciennes, Mons, Louvain, Liège, Beauvais, Chartres, Troyes, Metz and Dijon. For the rest, the cities we hear of probably numbered between 2,000 and 10,000.

Because many towns grew up around castles, the distinction between a small town and a castle was not at all clear-cut and, indeed, in the Holy Land and elsewhere we know of towns founded in castles, while Latin terminology often uses confusingly overlapping words which further obscures the distinction. The basic strength of the fortified city, as of the castle, rested in its garrison and political connections, whether as part of a state, such as Ghent and Bruges within Flanders, or Paris within the Capetian monarchy, or as a city–state with alliances of its own. In this sense, the strategic problem for the attacker was the same – to isolate the target from a friendly field-army or the support of a network of castles.

It was simply more difficult for a besieger to mount a successful assault on a city or to cut it off beyond all hope of relief, both because of its size and because of the problem of sustaining a large army over a period of time. All besiegers faced certain common problems.

Any city or castle could obviously be blockaded, and so would eventually fall from starvation if relief did not arrive. But the besieger himself was just as likely to suffer from supply problems as the besieged, and was more exposed to weather and disease. In 1184, hunger forced the retreat of an allied attack on the county of Hainaut, while in 1198 the Piacenzans could not assault Borgo San Donnino because of drought, followed by bad winter weather.

The presence of a relief army imposed terrible risks on an attacker. At the siege of Acre, the crusaders dug earthworks that had to be manned when they attacked the city, lest they be taken in the rear by Saladin's army; Philip Augustus did the same against an English relief force at Château Gaillard. Richard I argued against an attack on Jerusalem in 1192 because Saladin's army could cut his communications with the coast. In 1199, the Piacenzans and Milanese were forced to withdraw from the siege of Castelnuovo Bocca d'Adda by the Cremonans, whose relief force established itself nearby in a fortified camp, and in 1237 the Milanese and their allies prevented Frederick II from besieging Brescia by establishing a similar camp 25km to the south, on the Lusignolo.

The problems of a major siege were aggravated by the loose and composite nature of medieval armies. Lack of discipline and a less than alert guard probably explains how Mathilda escaped from Oxford in 1142. At Ascalon in 1153, the Templars forced a breach in the walls, but refused to allow others to exploit it, with disastrous results. In 1238, Frederick II was anxious to follow up his great victory at Cortenova in the previous year, but he was unable to gather a sizeable army until July, and then it was with a very motley force that he attacked Brescia – Germans, Cremonans, Apulians, Saracens, Tuscans, English, French, Spanish, Provençals and even Greeks are mentioned, each with their own leaders.

The siege seems to have been decided upon at a very late stage, for it was only after the arrival of the young King Henry in June that the army gathered. By that time, the four months' supply of rations that Frederick had commanded the Cremonans to take with them must have been running low. Although the only serious relief effort was an attack by the Piacenzans on Cremona, the siege, begun on 11 July, seems to have been conducted in a dilatory way which failed to prevent Brescian sallies, one of which, in August, captured Frederick's engineer, Calamandrinus, who was persuaded to work for the city. It was not until September that great siege towers were built and serious assaults made, but by then it was too late and inclement weather forced the imperial army to return to Cremona.

In February 1248, Frederick II's army was encamped in his siege-city of Victoria outside Parma when the besieged noted his absence – he had gone hunting. A minor skirmish of a few knights on both sides led to a determined sally by the Parmans, which panicked the imperial army before Frederick could impose order – the result was a major defeat for the imperialists. Edward I's siege of Caerlaverock in 1300 began with futile assaults by notables intent on displaying their bravery; these were soon replaced by a systematic siege.

The factor that distinguished siege warfare against important cities was their enormous potential for resistance. Street-fighting was just as costly in the Middle Ages as at Stalingrad. When the crusader army reached Toulouse in 1217, the city was virtually unfortified, but the crusaders were unable to enter because the citizens barricaded the streets and showered the attackers with missiles from the rooftops. At Mansourah, over 300 mounted knights were lost when they charged into the town and were overwhelmed by blocks of wood thrown down from the houses.

When the First Crusade attacked Antioch in October 1097, their army of about 50,000 faced a garrison of no more than 5,000 Turks, who had limited support from the population, many of whom were Christians. But the walls were 10km round and enclosed an area nearly 3km long and 2km wide. On the west they abutted the river Orontes, while to the east they rose abruptly up the mountainside to 500m; the more vulnerable north side was reinforced by barbicans. This strong city wall dated from Justinian's time and it was defended by a hierarchy of great and lesser towers. The crusaders were not even able to blockade all of the main gates until April 1098, after seven months of siege. The risk that they ran was dispersal of forces, which might open them to defeat in detail by a determined sally, precisely the fate of Kerbogah's army on 28 June 1098, after his siege of the crusaders who had obtained entry to Antioch by betrayal.

Similarly, in Italy, Barbarossa's first siege of Milan in 1158 was dogged by many sallies because his army was stretched out around the walls. By contrast with the garrison of Antioch, the Milanese enjoyed the support of the city population, whose limitations as soldiers counted for less behind city walls. Internal lines enabled defenders to launch effective sallies: it was probably for this reason that on the eve of the crusader attack in 1099, Jerusalem was reinforced with 400 horsemen. Medieval pictures almost always show knights in besieging armies; their mobility was necessary to defend against such sudden attacks. It is worth noting that the destruction of Frederick II's siege-city of Victoria began with a small cavalry skirmish.
   

[Longmane]

pt2

To attack a large city was an enormous undertaking, involving strong and able command, special equipment and personnel, persistence and, above all, organization to sustain forces. These qualities were not commonly combined in medieval armies, although they were demonstrated by the First Crusade at Antioch, to a remarkable degree.

Baldwin I of Jerusalem maintained the siege of Tyre from November 1111 to April 1112 using earthwork fortifications to protect his army from relief forces, and constructing formidable siege-towers. In the end, he failed because the citizens put up a stubborn and intelligent defence, could count on supply by sea and knew that a relief army was imminent. In 1124, the same disciplined effort – this time supported by a Venetian fleet – was successful. The siege of Ascalon, from 1153 to 1154, was a triumph of organization and determination over adversity. The siege of Lisbon in 1147–8 enjoyed remarkable success, but there was tension between the Portugese, the Anglo-Normans, the Germans and the Flemings over booty. During the Third Crusade, the siege of Acre, sustained for two years from August 1189, was badly hampered by friction between various groups, notably those of Richard I and Philip Augustus.

Frederick Barbarossa's enormous exertions against Milan illustrate the problems of siege very well. Barbarossa wanted to reassert imperial authority in the old Lombard Kingdom, but Milan was deeply opposed. After the failure of his early efforts to come to terms, Barbarossa besieged Milan with a great army in 1158, but he was never able to isolate the city, and many of his nobles tired of the bitter conflict, forcing him to come to terms at Roncaglia in September 1158. This settlement broke down, chiefly because Barbarossa needed the support of the imperialist cities; amongst them was Cremona, which wanted to weaken Milan by destroying Crema and the fortifications of Piacenza.

The siege of Crema, from 2 July 1159 until 27 January 1160, was an immense effort by Barbarossa. Although relatively small, the city was well fortified and required an all-out effort, with the use of complex siege machinery. After its fall, Frederick's army melted away, leaving the initiative to Milan, which tried to seize imperial Lodi and to cut Frederick's communications by isolating Como: armed confrontations resulted, with a pitched battle at Carcano on 9 August 1160 in which Barbarossa was defeated. Only in May 1161 was Milan besieged, and by late August the bitter fighting prompted some of the German nobles to seek a settlement with Milan; Rainald of Dassel prevented this by ambushing their envoys. It was not until March 1162 that Milan capitulated.

The attack on Milan strained even Barbarossa's resources. To sustain a war with so radical an objective – the destruction of an enemy city – was a major achievement in a world in which military activity was normally fitful. But a military solution in the Lombard plain was impossible, for the cities were too numerous and their political connections were too ramified, and Barbarossa failed to create a political solution after the fall of Milan. When Verona rebelled in 1164, much of eastern Lombardy followed – the emperor found himself with few Germans and "the Lombards were reluctant to come to his assistance".

[Longmane]

pt3

Toulouse, in southern France, was another great city which demonstrated its resilience in the face of a determined attack. It defied the army of the Albigensian Crusade in 1211: Simon de Montfort was unable to surround the city, whose walls were three miles round, and he could not depend on reinforcements. But, decisively, the crusaders were starving outside the city while Toulouse was able to buy food through its other gates, so after two weeks the siege was raised. The crusader army went on to attack Moissac, but even this small walled town defied them for a month, and in the end fell because of dissension between the garrison of knights and German mercenaries and the citizens.

Through changing political conditions, the walls of Toulouse were almost destroyed in 1215–16, but in September 1217 Count Raymond of Toulouse regained the city and once again de Montfort and his crusading army laid siege in October 1217. The citizens were united in their defiance of the crusader army and they organized themselves efficiently – men, women and even children. They improvised fortifications with earthworks and timber, and, where these did not exist, poured down stones and other missiles from the roofs upon the attacking French, making the narrow streets impassable.

The citadel, the Château de Narbonne, was held by the French, but it was completely cut off from the city. Once the fury of their first attacks was spent, the French settled down for a long siege. Focaud of Berzy advised Simon: "We must work out how to maintain a long siege so as to destroy the town. Every day we must make raids across the whole country so as to deprive them of corn, grain, of trees too and vines, of salt, timber and other provisions. In this way we shall force them to surrender."

By January 1218, reinforcements from France were starting to arrive, and more poured in in May and June, but although savage assaults were mounted from both sides of the city, supported by elaborate siege equipment, it was never wholly closed off, and this enabled the citizens to receive reinforcements. When Simon de Montfort was killed by a stone from a mangonel on 26 June 1217, the siege was abandoned. The city was besieged for a third time in 1228, but ultimately it surrendered to the overwhelming power of the French monarchy.

In fact, many sieges of cities were unsuccessful. Frederick II had huge resources, but at Brescia in 1238 his large army was poorly organized and unable to prevent effective sallies by the besieged. At Parma in 1247, his allies blocked the river to prevent food entering the city, which soon became desperate, but a sally caught his forces unprepared. In 1243, tiny Viterbo defected to his enemies at a time when he had dismissed his forces and defied the troops that he raised with Pisan loans. In 1241, the small city of Faenza eventually fell after a bitter six-month siege, which deflected his army from Bologna, its main goal. 

By contrast, as we have seen, Henry II and his son Richard had been able to reduce castles with relative ease. The castle was formidable against an enemy with limited wealth and where, as in thirteenth-century Germany, warfare was on a limited scale, but only an exceptionally strong castle could resist a monarch who could mobilize resources on Henry II's scale.

In Spain, the Christian kingdoms exploited the strength of cities to defend their frontiers. As the kingdoms advanced into Islamic territory, they planted cities to secure their new frontiers. Citizens were recruited by the offer of land, on generous terms. Fired by a mixture of religious zeal, well founded fear and anxiety to defend what they held, the settlers made good garrisons quite ready to sally out to attack Muslim ravagers and to offer determined resistance in the face of greater attacks. Even when Alfonso VIII was defeated at Alarcos in 1195, the Muslims were unable to make much progress in reconquering the lands, because the cities stood against them, only three minor ones falling.

Attacks on cities were relatively uncommon in northern Europe before the major growth of cities in the thirteenth century. London was besieged by Cnut in 1016, but it offered no resistance to Duke William in 1066 and stood no siege in the civil wars under Stephen, King John and Henry III, although it played a role in all three upheavals.

In Germany, attacks on cities were very frequent, and were essentially "a by-product of the fractured political landscape into which Germany and its sub-regions developed by the thirteenth century". The dissolution of the kingdom, especially after the death of Frederick II in 1250, produced a chaos of competing forces – many of them very small indeed – and free cities of one kind or another loomed large amongst them. These sieges almost always failed, in part because of the strength of town fortifications, but the major factor must surely have been the small size of the competing political units and their inability to sustain conflict over a long period of time.

Siege was a test of political will and resources on both sides. The defenders needed to provide food and to maintain hope of ultimate success: the task was very much the same on the attackers' side, complicated by the need to provide shelter and an infrastructure of support. Strong fortifications were an important factor in this struggle of wills.

The fortifications of cities were not, in principle, very different from those of castles. Milan's in 1158 incorporated a Roman arch which stood outside the main circuit, while Alessandria was a new city, whose fortifications at the time of Barbarossa's unsuccessful siege of 1174–5 were probably earth and timber. At the time of the First Crusade vulnerable sections of the defences of Antioch and Jerusalem were reinforced by double walls, and the twelfth-century sources indicate that most of the important cities of the Palestinian littoral enjoyed this form of protection: these were almost certainly the inheritance of the Roman past.

The great walls of Constantinople were of course the example of systematic fortification. Such relatively sophisticated structures were rare in the West. Crema had a double wall at the time of its siege in 1159–60, while at Carcassonne in 1228–39 a strong concentric pattern was developed, and this was used in the new fortifications at Oxford shortly after. St Louis constructed Aigues Mortes as a modern fortification from which to launch his crusades. In the East, he recreated Caeserea with massive stone-lined ditches and a steeply raked talus on the wall side, on the model of Belvoir. Acre's walls were rebuilt on much the same pattern in the thirteenth century; the city fell to al-Ashraf after a siege of only six weeks, but its garrison was not numerous and the enemy was overwhelming.

In North Wales, the walls of Conway and Caernarfon shared the modern sophistication of the castles that sheltered them. In these advanced fortifications, all of the devices found in the castle – machicolations, angled arrow-slits and sally-gates – were emulated. Such complex structures were probably as rare as concentric castles, although the strengthening of city defences with stone walls was a feature of the thirteenth century, and barbicans seem to have been a common addition at weak points. Determination compensated for lack of walls at Toulouse in 1217, and at Alessandria from 27 October 1174 to 12 April 1175, when the threat posed by the army of the Lombard League persuaded Barbarossa to raise the siege.

[Longmane]

Pt4

The defences of cities were often strengthened by the incorporation of a citadel. In Europe and the Middle East, castles often gave birth to towns, which nestled around them and were walled. At Ghent, the comital castle dominated the town. Montgomery was laid out as a town when the new castle was built there in the 1220s. Dryslwyn was a small castle-town of the later thirteenth century.

But as cities grew, citadels became quite distinct entities within the defence. In Laon a "new tower", built by Heribert II in the 920s, held out after the city had fallen in 931 and 949, but fell to mining. During the siege of 985, the commercial quarter of Verdun seems to have served as an inner core for the defence. At Antioch, the citadel stood on the walls and at Jerusalem the famous Tower of David was on the west perimeter. In 1243, the citadel of Viterbo resisted when the city fell. An old Roman fort, the Château de Narbonne, was the citadel of Toulouse, but the demolitions of 1215–16 removed it from the circuit of the walls, and it served as headquarters of the Albigensian Crusade in the great siege of 1217–18. Thirteenth century Acre was defended by double walls with a deep ditch between, and a similar arrangement cut off the suburb of Montmusard from the port proper, where the Templar castle served as a citadel. Citadels on the perimeter sometimes strengthened the defences of a city, although Antioch was an exception. The citadel there was so remote that during the crusader siege it had no influence whatsoever. When the crusaders seized the city, the citadel on its remote mountain-peak held out against them and admitted the forces of Kerbogah when he besieged them in Antioch shortly after.

Citadels, like keeps in castles, must have given confidence to those of the defenders who might find an ultimate refuge in them. However, they often represented the menace of some outside ruling power and were intended to hold down the city rather than defend it, notably in early Norman England.

In the end it was the garrison, not the walls, that mattered. Surprise was by far the best means of seizing a fortified place, and dissension within a city or garrison could be fatal. In 1236, an allied army of the eastern Lombard cities of Vicenza, Trevio, Padua and Mantua was being held off by Ezzelino of Romano when Frederick II suddenly marched from Cremona and seized Vicenza. This was possible because of the absence of many Vicenzan soldiers, and because Ezzelino had already enlisted sympathizers within the city. In the wake of this blow most of eastern Lombardy, notably Padua and Trevio, fell to the imperial cause. At Moissac in August 1212, as we have noted, the citizens lacked the will to fight off the crusader siege although the garrison was willing. Parma defected from the cause of Frederick II in 1247 when Parman exiles made a sally into the city and gained the upper hand.

If surprise was impossible, a determined assault well pressed home was often enough, as at Tonbridge castle in 1088, which Wiliam Rufus's troops seized by storm on the second day of the siege. The army of the First Crusade tried to rush the formidable defences of Jerusalem equipped only with a single siege-ladder in June 1099. According to the Gesta Stephani, in 1144 Stephen captured Winchcombe by ordering his troops to rush at it under "a cloud of arrows". The castle was newly built on a high mound, which suggests that it was of wood, and it had only a small garrison. The assault failed, but the garrison quickly decided to surrender on terms.

The fall of Winchcombe nicely illustrates the combination of psychological and physical factors which was called for in siege warfare. Stephen's assault was a clear show of determination and the garrison, feeling isolated and outnumbered, decided on the better part of valour. In 1144, Baldwin III was unable to take Li Vaux Moise but devastated the countryside, and so persuaded the inhabitants to turn against the Turkish garrison. Before he besieged Taillebourg, Richard's opening gambit was also destruction of the countryside, provoking the garrison to an ill-considered sally which enabled him to capture the place.

Besiegers and besieged sometimes resorted to cruder methods to depress enemy morale. At Nicaea in 1097, and again at Antioch, the crusaders demoralized the garrisons by impaling the heads of their dead colleagues. Saladin did the same during his siege of Tiberias in 1187, while in 1153 the defenders of Ascalon hung the bodies of those killed in a failed assault over the battlements. During the siege of Milan, Adam de Palatio was hanged at the order of Frederick Barbarossa after a successful Milanese sally. When Barbarossa captured Corno Vecchio, all of the garrison had their right hands cut off. In 1224, Henry III swore that he would hang the garrison of Bedford if it failed to surrender, and duly did when the castle had to be stormed. Edward I reluctantly spared the gallant garrison of Stirling. But if terror failed, specialized techniques and tactics were needed.

[Longmane]

Pt5

Castles were built to attack towns or other castles. William of Normandy used four against Domfront in 1052 and built one for his successful siege of Arques in 1053–4. The army of the First Crusade constructed three at Antioch. In 1102, Raymond of Toulouse began the famous Mont Pèlerin on a ridge dominating the city of Tripoli, which only fell long after his death in 1109; thereafter, the increasingly elaborate castle served as a formidable redoubt of defence for the city. At Tyre in 1111, Baldwin I built a fortified camp for his besieging force. At Alençon in 1118, the citizens admitted Fulk of Anjou into the town and he constructed what the sources refer to as a "park", an earthwork camp, as a base for his siege of the castle. Barbarossa built a camp for his siege of Manfred's castle near Castelleone in 1186, and the place surrendered on terms. In 1247, Frederick II created the grandiosely named "city" of Victoria, but his army was surprised by the besieged Parmans and destroyed.

A camp provided shelter for the besiegers, protected them and their equipment from sallies, and provided a logistic base, as witness the huge booty of food seized by the Parmans at Victoria. At the same time, there was an obvious coercive purpose: Victoria was built only four bow shots away from Parma. However, fortified camps were not an invariable condition of success: the First Crusade built none during the siege of Jerusalem. By contrast, during the Third Crusade very elaborate fortifications ringed the crusader camp before Acre.  Sieges, especially of lesser castles, were often undertaken in a very casual way if no relief army was anticipated and the place was not strong, but bases were essential for operations against major fortifications.

There were a variety of stratagems for attacking fortifications. Wooden castles could be burned, although this was never as easy as we tend to think. An earthwork slope such as that of the motte made approach difficult – but not impossible, as the picture of Dinan in the Bayeux Tapestry shows. Setting fire against timber was by no means easy: Raymond of Aguilers spoke of mallets set with spikes being hurled at crusader machines during the final attack on Jerusalem in 1099, and another source tells us that a "newly invented" machine threw fire at the assault by the Count of Toulouse. The sources make fairly frequent reference to "Greek Fire" being used by the Muslims at the siege of Acre. The availability of naphtha and other oil derivatives in surface deposits probably explains why such fire-throwing was more common in the Middle East than in the West, where creating any form of "sticky fire" that could adhere to a wooden palisade and ignite it must have been difficult – and almost impossible in wet weather.

A frequent stratagem was to undermine or batter down a wall with a ram or picks under the cover of showers of missiles. The approach of the attackers could be protected by mantlets, large panels of woven light wood. Armoured roofs or penthouses could be constructed, most simply of heavy logs leant against the defending wall, to shelter men working below. Alternatively, the roof could be mounted on wheels: such structures might be called "cats" or "sows". At Nicaea in 1097, most assaults were delivered by penthouses, some of which sheltered battering-rams. A battering-ram, used to break through the outer wall of Jerusalem in 1099, was then burned to make way for the siege-tower that was brought up behind it to dominate the main wall.

Battering-rams suspended in siege-towers were used at Tyre in 1111–12, but the defenders used grappling irons and ropes to foil them. At Acre during the Third Crusade, a great ram protected by a penthouse was deployed, but the Muslim garrison managed to burn it. Edward I used a ram at Stirling in 1304. Penthouses could be employed to cover troops approaching a wall and to provide fire-cover: at the first siege of Toulouse in 1211 "cats" of boiled leather supported the attackers. An enormous wooden penthouse, massively armed, led the final abortive attack in 1217, in the course of which Simon de Montfort was killed.

Deep mining was an alternative approach to undermining city or castle defences. Zengi seized Edessa in 1144 by undermining the walls using a system of natural tunnels. At Rochester in 1215, part of the curtain wall and then the southeast corner of the keep were undermined by a deep sap created by miners: in the case of the latter, the props in the sap were burned with the aid of the fat of 40 pigs. At Bedford, too, in 1224 the inner bailey and the keep were mined. In the Holy Land, both Crac des Chevaliers in 1271 and Marqab in 1285 fell to mining operations.

But the success of deep mining depended on soil conditions: at Dover the soft rock made for easy progress and reduced the need for careful propping, but the miners with Edward I in Scotland in 1300 were of little use in the siege of marshy Caerlaverock. At Acre during the Third Crusade, countermining blocked French attempts to bring down the walls. At Bungay castle in Suffolk, a mine and a countermine, dating from 1174, are intact. At Alessandria, Barbarossa's "cat" covered the filling in of the ditch, supported a siege-tower and served to cover deep mining, but the defenders managed to collapse the tunnels.

Even when mining was successful, the results were not always decisive; at Nicaea the breach was made late in the day and filled in overnight, while at Dover and Acre defences were improvised after breaches were made. Mining was also relatively slow and demanded skilled labour, which might not be available.  Moreover, fortifications could incorporate design features to prevent it. Heavy batters in front of the wall could cause shallow mines to collapse before they reached anything vital, while cisterns could be sited across likely lines of sap, offering the possibility of flooding diggings. Overall, however, mining was the most consistently successful tactic used against fortifications.

[Longmane]

Pt6

An alternative approach was to build huge wooden towers to overawe the defences and enable others to attack them.

The Vikings attacked Paris with one in 885–6. At Verdun in 985, the siege-tower was dragged by ropes passed around stakes close to the city wall, so that the oxen were moving away from the enemy. In 1087, a Pisan and Genoese expedition employed similar towers to capture Pantelleria.

Such machines were not necessarily mobile. At the siege of Pont Audemar in 1123, Henry I built a tower, but it was only used to rain missiles into the castle, whose garrison had first to watch the burning of the town around them and the devastation of the countryside. At Coria in Spain in 1138, wooden towers acted as firing platforms, while at Bedford in 1224 the huge towers built for Henry III seem to have been used to mount various kinds of stone-throwers which deluged the walls with missiles.  At Ma'arra on the First Crusade, the tower built by Raymond of St Gilles was clearly mobile, but its purpose again was to act simply as a fire-base to cover mining and assaults by ladder, which eventually carried the day. This was probably the intended purpose of the towers in the siege of Jerusalem in July 1099, but that of Godfrey was fortuitously brought up close to the wall and a bridge was improvised to make entry.

Fully mobile siege-towers with drawbridges to launch an assault became a feature of important sieges, notably in the Holy Land where they were pre-eminent in the capture of the Muslim cities of the coast. Barbarossa used them in Lombardy, and Edward I attacked Bothwell castle in 1301 with a tower that had been transported in sections and was covered in hides against fire. In the West, towers continued to be important right down to the invention of cannons. At Lisbon, the Anglo-Norman force brought up a tower some 28m high and when this was destroyed, they deployed another one, 25m high, apparently built and commanded by a Pisan engineer; this proved to be the final straw for the garrison, which surrendered.

Such devices had very obvious limitations. The ground might be very unfavourable, as at 'Arqa on the First Crusade, where the city walls crowned a steep slope. In southern Italy, the relative isolation of inland places may have made it difficult to get siege-machinery to them. Even where the ground was generally suitable, it had to be smoothed and often ditches obstructed the route to the walls; at Jerusalem, the Count of Toulouse paid one penny for every three stones cast into the moat by the southern wall, while at Tortosa in 1148 a huge ditch 43m wide and 32m deep had to be filled.

The clumsiness and weight of the towers meant that they needed to be built as close as possible to the point of attack. At Jerusalem in 1099, the defenders of the northern wall built up the walls, set up catapults and prepared beams and padding to repel the expected attack. The crusaders changed their assault point, and this was probably the decisive factor in the siege: near Zion Gate the Count of Toulouse had no room for manoeuvre and his tower was ultimately incapacitated by catapult attack and fire. A similar fate befell Bohemond's tower in the attack on Durazzo in 1108.

Fire was the great enemy; the successful machine at Lisbon was covered with wet hides, with the animal tails hanging down for maximum flow, while at Jerusalem Godfrey's tower was soaked in vinegar against the defenders' "Greek Fire". During the siege of Tyre, the defenders built a war-crane on the city walls, which overtopped the crusader siegetowers and destroyed them by dropping incendiaries on to them.

Siege-towers were remarkable structures, but they were not a certain solution to the problem of attacking fortifications. Terrain was often a problem and countermeasures by the besieged could destroy them. Above all, they were costly and justified only for major objectives.

[Longmane]

Pt7

Artillery capable of battering fortifications and defenders into surrender, known in Roman times, continued to be used.

At the siege of Paris in 885– 6, mangana, catapulta and balistae are mentioned as hurling missiles. But these are only a few of the bewildering variety of words used by medieval writers to refer to siege engines. Unfortunately, their use is inconsistent and such descriptions as they give are confusing.

Orderic tells us that at Brévol in 1092 a great machine was rolled up to the wall, which suggests a tower or penthouse, but adds that it hurled stones: it is possible that this was some kind of platform that accommodated a stone-thrower. Otto of Freising refers to a mangonel as a kind of balista, although this was a quite different kind of machine. The word petraria, rendered as perrier in French, is often used but this merely means a stone-thrower. William of Tyre and Guillaume le Breton both clearly suggest that perriers were for heavy bombardment while mangana were lighter anti-personnel weapons, and the same notion about the latter is found in the Chanson de la Croisade Albigeoise.

Mangonella would seem to be only a diminutive of mangana; in Roman times this referred to a weapon that depended for power on torsion. The mangana was a machine with a single arm, whose bottom end was embedded in a massive horizontal winding of sinew: the arm was bent back against the torsion of the winding and, when released, flew forward against a robust frame, hurling a stone out of a cup or sling on its end. The crash of impact between arm and bar probably explains the nickname onager, "the mule", for this machine. The missile was thus launched in an arc like the shell from a howitzer.

The Roman balista was a crossbow-like weapon, but the "bow" consisted of two arms, each mounted in a vertically wound gathering of sinews, which provided the tension when the string was drawn to fire a bolt or ball: its trajectory would have been flat. The term balista in medieval sources generally refers to crossbows. Clearly related was the arcu-balista or later springald, a flat-trajectory weapon rather like a giant crossbow, which was widely used in sieges.

The traction-trebuchet was the dominant form of artillery in our period. It was a device that originated in China and was transmitted to Europe by about the ninth century via the Arab world. It was essentially a beam pivoted between two high uprights: when the beam was pulled at one end by a team of men, the other flew up until a missile was released in an arcing trajectory either from a cup or, more effectively, from a sling. The pulling end of the beam was by far the shorter, in a ratio of perhaps 1: 5, and the efficiency of the engine was enormously enhanced by the use of a sling on the throwing end. This kind of lever artillery varied in size, which partly accounts for the inconsistency of the language used to describe it; broadly, it would seem that petraria and mangana indicate sizeable examples and mangonella and tormenta lesser ones.

There is no reason to believe that the principle of torsion was forgotten, but the impact of the throwing beam must have put enormous strain on the structure of the onager, which would have had to be very heavy to last any time, and of extraordinary size and weight to throw a large missile: lever-action machines were probably lighter and more durable. Moreover, the technology of lever-artillery could be easily assimilated by a society in which increasingly complex machinery, such as water mills with pivoting wheels and gears, was becoming common. At the siege of Jerusalem in 1099, both Albert of Aachen and Tudebode report that the crusaders used machines powerful enough to throw captured spies into the city; in the case cited by Tudebode, the machine had a sling, which, together with the presumed power, strongly suggests a traction-trebuchet and implies that they were not a novelty.

[Longmane]

Pt8

There is a good example of a traction-trebuchet at Caerphilly castle, which seems to approximate in size those illustrated in the Maciejowski Bible and the work of Peter of Eboli: it throws a 15kg ball about 120m. It would have taken a long time to demolish stonework and was probably at its most effective against the fighting top of a wall or tower, the merlons, walkways, machicolations and hoardings that were so much more vulnerable. This would have shortened its range to 50–60m, although mounting it on a tower or a mound, as Edward I did at Edinburgh, would increase this.  But machines were always very vulnerable to a sudden sally and had to be protected carefully: at the siege of Acre, Philip of France failed to do this and his artillery was burned. At the siege of Jacob's Ford, Saladin sent his men to find vine poles to set around his siege engines.

Of course, the effectiveness of lever-artillery could be enhanced by continuous use and/or deployment of large numbers of machines. At Rouen in 1174, batteries of machines were kept going in eight-hour shifts. Uninterrupted action by massed forces of large machines would surely have smashed masonry in time, but the conditions in which large numbers of such machines could be gathered and operated were relatively rare, and before the end of the twelfth century there is little evidence of artillery smashing the main masses of castles and walled cities. Moreover, defenders could make very good use of traction-trebuchets which, if they were mounted on towers, could certainly out range attacking machines.

In sieges in the Holy Land, siege-towers were the most important engines of assault. At Jerusalem in 1099, the defenders mustered 14 missile-throwers and concentrated nine of them against the tower of the Count of Toulouse, which was severely damaged. At Tyre in 1124, an Armenian artillery expert was brought in to direct counter-fire at the defenders' machines. At Milan in 1158, Barbarossa's troops seized the Roman arch and mounted a traction-trebuchet on it, but the defenders replied with two machines of their own, firing from the walls, and put this out of action.

Accounts of late twelfth-century sieges do not suggest that siege-warfare had undergone any considerable change. On 26 July 1188, Saladin and his son al-Malik al Zahir besieged Saône. The Muslim army divided into two. Saladin attacked the east wall from across the great rock-cut ditch with four stone-throwers, causing damage at the northeast corner, where signs of repair are still evident. Al-Zahir's forces established themselves by the northern wall of the castle-town, where they set up two siege engines, almost certainly at the spot where the walls follow the clifftop and leave a roughly triangular and relatively flat piece of land undefended. On 29 July, al-Zahir's forces made a breach and followed it up with a sudden assault, surprising the defenders and pouring into the town and the main fortress. The garrison fled to the great towers and negotiated terms of surrender.

The impact on the walls of the battering by a relatively small number of engines working over only two days is interesting, but it must be remembered that there was no counter-fire from within the castle. The main cause of the fall of Saône was simply that its garrison was hopelessly outnumbered, cut off from all hope of aid, and subjected to a two-pronged attack by Saladin's huge army, which divided their forces.

Again, at the siege of Acre we hear of severe damage being inflicted upon the walls of the city. Roger of Hovenden reports an unsuccessful attack made into a breach created by French engines, while Alberic Clement lost his life in another; although, interestingly, in this case only a part of the wall had fallen and the attackers had to carry in siege-ladders. Richard's men broke down a tower, but the rock-thrower seems to have supplemented mining, and this reminds us that, at the siege of Château Gaillard, Philip Augustus used a large traction-trebuchet to demolish the inner gate only after it had been undermined.

The garrison of Acre were well supplied with engines of their own and destroyed the French traction-trebuchet, "Malvoisin". Their chief weapon against assault seems to have been "Greek Fire", brought to them by a Damascene coppersmith, which at least sometimes was projected by artillery. Descriptions of the damage inflicted suggest that it was largely on the walkways and that the walls were intact: a petraria built by the crusaders damaged part of a tower by shaking down two poles' length of its wall. This probably means a part of the walkway wall rather than the main structure. Moreover, Acre was besieged for a very long time and attacked by many methods – including mining, which may well have done much of the damage.

[Longmane]

Pt9

In the very late twelfth and early thirteenth centuries, a new word comes to be used to describe hurling engines, variously spelt trabuchetum, tribok or trabocco. In about 1270, the French engineer, Villard de Honnecourt, drew a plan for a trabucet, and his description of the counterweight-trebuchet is supported by Egidio Colonna, writing in c. 1280, and Marino Sanudo, in about 1320.

This kind of machine acted on the lever principle, but its load end was pulled down by a gang of men against a massive weight attached to its front end, normally using a winch for the purpose. The sling was then attached to the load end with a missile inserted, and when the rope securing it was released, the load end swung up, propelled by the massive weight at the front end. A radical improvement was the attachment of the weight in a pivoted basket.

The range and power obviously depended on the size of the beam and the weights employed, but this kind of engine was capable of throwing substantial missiles. The front-end weight made for much greater accuracy than could be provided by a team of men, whose pull on the traction-trebuchet inevitably varied, thus altering the range. As in the traction-trebuchet, the principle was of a beam pivoted on a triangular frame. Comparison of two good modern replicas – one Danish and the other at Caerphilly castle – indicates the scale of the machine:


                        Danish (m)    Caerphilly (m)
Arm length            6.5                6.5
Behind pivot          5.5               5.15
Tower height          4.8               4.2
Frame length          8.5               6
Frame width           7                  4.2

Massive beams of timber are used in both machines, and the Danish example has cast a 47kg missile 100m.  This would certainly be enough to inflict real damage on the main structure of a stone castle.

The earliest use of the term "trebuchet" is by Codagnellus, who says that a trabuchis was used at the siege of Castelnuovo Bocca d'Adda in 1199: this has been seized upon as evidence of the first appearance of the new counterweight-trebuchet in the west. However, on three of the occasions when he uses the word, Codagnellus seems to indicate a light weapon.

The Genoese annals of the early thirteenth century mention trebuchets along with other weapons, sometimes specifically referring to them as quickly built. Rolandino of Padua mentions trebuchets and other machines mounted on a wooden belfry tower at the siege of Mussolente in 1249. This suggests that the term could be applied to a light weapon. But an illustration from the Genoese annals of 1227 offers very different evidence. It shows large traction-trebuchets with their firing beams in the characteristic semi-horizontal rest position; by contrast, two other machines at rest have their beams vertical, which is the characteristic position of the counterweight-trebuchets. The scale of the drawing makes it clear that these were very large, heavy machines.

French evidence from the early thirteenth century indicates very clearly that the trebuchet was a large engine. The Chanson de la Croisade Albigeoise reports that Simon de Montfort used a trabuquet against Castelnaudary in September 1211: this was evidently a large and powerful machine, for with a single stone it demolished a tower, and with another a hall. Even allowing for poetic licence, this is suggestive. The Count of Toulouse attempted to retake the castle a little later, but was forced to abandon his camp and with it a trebuchet.

Later in the Chanson there is a much clearer indication that the word trabuquet is being applied to a counterweight-trebuchet. As the defenders of Toulouse in 1217 prepared to meet the crusader attack, they "ran to the ropes and wound the trebuchets", while later we are told that, having set dressed stone in the slings of their trabuquetz "they released the ropes". These are very clear indications of what we are dealing with: the beam of a counterweight-trebuchet had to be "wound" or tensioned down and then "released": these actions are quite different from what was required of a traction-trebuchet. Moreover, the general descriptions offered in this poem suggest sizeable engines, for these weapons did great damage to the citadel of Toulouse held by the crusaders.

At Toulouse in 1219, trebuchets were prepared for use against Louis VIII; they were differentiated from other stone-throwers by being put in the charge of men who were experienced in using them. The Tours chronicler reports that in 1226 the Avignonese used a similar array of machines, including trebuchets, against Louis. The first mention of a trebuchet in Germany, in 1212, says that it was then regarded as a new machine.

English sources do not use the term "trebuchet" much in the thirteenth century. The Dunstable annalist says that Prince Louis of France brought a tribuchetta to the siege of Dover in 1217, but mentions only petraria, maggunella and balisterii quam fundibularii being used against Bedford in 1224, and Matthew Paris mentions the same range of machines. In 1224, Jordan the Carpenter made a trebuchet for Dover and in 1225 another for Windsor.  At the siege of Kenilworth in 1266, Edward I deployed a number of balistae, some mounted on a tower, and 11 petrarii; the defenders replied with mangonellae.

The huge machine built in August 1287 to attack Dryslwyn, and subsequently transported by between 40 and 60 oxen to batter Newcastle Emlyn into submission in January 1288, was probably a trebuchet, but the word is not used. The great engine which Edward I was so anxious to use against Stirling in 1304 is described by a chronicler as immensis tormentis and by neutral terms in the records, although it is almost certain, as Michael Prestwich comments, that a counterweight-trebuchet was actually used.

[Longmane]

Pt10

The counterweight-trebuchet appears so suddenly that it was evidently an invention. Its creation must have been the outcome of careful thought and calculation, because performance depended on a number of variables, notably the shape of the hook that governed the release of the sling, the weight of the missile, the weight of the counterpoise, the ratio between the parts of the arm and the length of the sling. But formidable though it was, the counterweight-trebuchet did not radically alter the balance of advantage between attack and defence. Walls were built more strongly, and at Kenilworth, and later Caerphilly, the creation of large ponds around the main fortifications kept the weapon out of range.

The construction and operation of the counterweight-trebuchet was the province of specialist engineers, who were not always available, and it was ponderous to transport. Its use was, therefore, limited, and traction-trebuchets remained popular because they were simpler and cheaper. The weapon had a limited range: trials on modern replicas suggest that it was of the order of 100–120m, but at this distance projectiles would be striking the bases of walls rather than their weaker upper parts. Counterweight-trebuchets were deployed so close to their targets that the operators needed protection from the missiles of the defenders: the machine used against Dryslwyn and Newcastle Emlyn had a shelter to protect them.

The dynamics of the traction-trebuchet are so complex that it must have been very difficult to change range. For example, a lighter missile will only go further if adjustments are made to the sling and the hook. The operator must have had to make very careful judgements balancing range against weight of missile, and taking into account local topography, weather and the strength of the target, in order to locate the machine; once in situ it was unlikely to be moved. Moreover, the quality of the missiles mattered. At Castelnaudary, stones that would not shatter had to be brought from "a long league away"; even so, one of them shattered, limiting damage. At Acre, Richard used very hard stones brought from the West, which were so unusual that they were specially shown to Saladin.

Moreover, the counterweight-trebuchet could also be as useful to the defender as to the attacker. We have noted that traction-trebuchets were deployed on towers that gave them enhanced range. Counterweight-trebuchets could be built within the walls. At Toulouse, Simon de Montfort's great "cat" was smashed by a stone from a counterweight-trebuchet, and he was killed by one thrown by a traction-trebuchet, allegedly worked by women. An illustration of the siege of Savona by the Genoese in 1227 shows a traction-trebuchet on the city wall being struck by a stone from a much larger machine fired by the attackers, and there is a similar picture in a manuscript of Peter of Eboli.

In the Muslim East, enormous towers began to appear in the fortifications of the thirteenth century in order to carry counterweight-trebuchets: the most obvious example is the great square structure known as Baybars' Tower, which dominates the vulnerable southern wall of Crac des Chevaliers. The square towers at Bosra and the enormous round ones at Subeibe had the same function. This seems to reflect a much greater use of heavy missile-throwers in siege-warfare in the Middle East than in the West. Baybars even dragged such equipment up the terrible slopes of 'Akkar in 1271 after his success against Crac. At Acre in 1291, al-Ashraf deployed nearly 100 machines, including a great trebuchet called "The Victorious": this was siege-warfare on a scale unknown in the West.

[Longmane]

pt 11 (last part)

Western armies were occasional bodies, lacking a continuous existence which could nurture the special skills needed to build, operate and develop siege-equipment. Robert of Bellême and Gaston of Béarn were rare specialists at the turn of the eleventh and twelfth centuries. Even in the mid-twelfth century, Geoffrey of Anjou's engineering skills were evidently unusual. It is not strange that one of the penthouses built by the First Crusade to attack Nicaea in 1097 collapsed, while their mangonels were ineffective. In 1174, a Scottish traction-trebuchet was deployed against Wark castle, but its first missile fell on the team operating it. Many may have known in principle how to build machinery, but doing it was a different matter.

However, military architecture was developing in the twelfth century and commanders needed weapons against it. It was a Genoese sailor, William Ricau, who built the siege machinery of the Provençals at Jerusalem in 1099. Guintelmus, a great engineer, was high in the councils of Milan during the conflict with Barbarossa. During the siege of Milan, Marchesius of Crema enjoyed rich rewards when he defected to Barbarossa. The rivalry of the Italian cities, their wealth and their commercial and maritime background, brought together all the skills needed for construction, but great kings were quick to follow suit. Henry II had engineers in his train, and specialized operators of siege-equipment.


In the thirteenth century, engineers could enjoy great importance and their deeds are chronicled in the records of the period. Elias of Oxford served Richard I, while John bestowed a knight's fee upon Urricus. Masters Osbert and Bertram were prominent under Henry III. Edward I used a whole host of engineers and master-carpenters, supported by miners and others. Master Robert of Ulm supervised the mass of machinery deployed against Caerlaverock in 1300, and Master James of St George fulfilled the same role at Stirling in 1304. The engineer Jean de Mézos was raised to knighthood in 1254 by St Louis, while James I of Aragon employed the Italian engineer Nicoloso. Frederick II so valued his great Spanish engineer Calamandrinus that he kept him in shackles!

By the end of the twelfth century, such people had become so important that the writer Guiot de Provins was dismayed at the prospect of their dominating war. There was little risk of this, because they were rewarded much more modestly than the traditional military caste: in war, status and conformity to the canons of chivalrous behaviour counted for more.

It is an interesting reflection on the importance of status in war that the siege of Lisbon, although it was a major victory over Islam and saw the employment of siege-equipment on a large scale, never seems to have enjoyed great renown in northern Europe, almost certainly because no notable person was present.

In fact, armies usually deployed every possible technique and instrument of war when they really wanted to capture a city or castle. No single method of attack was outstandingly effective, so they all had to be tried. No machine in this period actually altered the balance of advantage between attack and defence. The best way to seize a fortification was to isolate it with overwhelming numbers which, self-evidently, could prevent any relief. This required good leadership, skill, determination, organization and plentiful supplies – difficult enough to achieve when armies were transient. It was pre-eminently kings who could achieve the conditions for success in siege warfare.

Strong centralized authority in England and France absorbed castles into the political system. They continued to have a military potential that could influence the political balance, and in times of weakness this could come to the fore. But their absorption into political systems reduced the need for sieges. In Germany after the death of Frederick II in 1250, political fragmentation mirrored that found in France at the beginning of our period, in a landscape dominated by castles; but large-scale siege employing complex machinery was rare, and the stalemate imposed by numerous cities and castles may even have increased the readiness to risk battle.

In Italy, siege was more common because the area was dominated by great cities. The crusader settlements in the Holy Land after the Third Crusade were anchored by a few cities and great castles, and they were gradually reduced by a series of epic sieges, culminating in that of Acre in 1291, by an Islamic world with a highly developed siege technique.

In all areas, fortifications continued to dominate the pattern of war. Successful siege could achieve all that victory in battle offered and perhaps more, but at the price of much the same risks. Both kinds of action required enormous political and financial investment which could easily be lost. Duke William of Normandy's large force outside Gerberoi was taken by surprise by a sally and was scattered, as was Frederick II's camp before Parma in 1247. Relief forces could appear: William the Conqueror could not prevent a relief entering Arques in 1054; the First Crusade had to fight off enemy armies during the sieges of Nicaea and Antioch; Philip Augustus was forced to abandon the siege of Verneuil in 1194, when Richard suddenly cut his communications; and Charles of Anjou failed before Messina in 1282, because an Aragonese army came to its relief.

Even when there were no such risks, the siege of a strong place was expensive: the siege of Bedford in 1224 was in part a political demonstration by the new king of his strength, but the employment of the latest in siege equipment and the concentration of large forces cost £1,311 18s. 2d. in wages alone, while the crushing of the Montforts in the siege of Kenilworth in 1266 required a huge effort and enormous expense.

Sieges were simply a very specialized form of battle. They did what battle in other societies was designed to do – to destroy the basic strength of the enemy and acquire it for your own use. Strong central authorities absorbed cities and castles and used them where appropriate for large-scale confrontations of their own. But where an attack on a fortification was necessary, it remained as hazardous and difficult as ever, because no development or set of developments in the course of this period altered the balance between defence and attack. In 1310, Frederick of Austria gathered an army of Rhinelanders and Swabians, and allied with the Archbishop of Salzburg to ravage Bavaria and seize Wels, before besieging the castle of Schaerding. They had a large army, against which Otto of Hungary and Duke Stephen of Bavaria could muster only hastily raised forces, but lack of food, bad weather and loss of horses forced the abandonment of the siege – the failings of armies remained much as before.