Siege Warfare

Generalities

The development of fortifications has always been dictated by the type of siege tactics and equipment used against them. The strength of the Norman keep lay in the extraordinary solidity of the construction of its high and thick walls. This structure, solid and tall, with no woodwork to be set on fire and no openings near the ground to be battered in, had an almost endless capacity for passive resistance. Even a weak and small garrison could hold on, of course, as long as its supplies lasted. However, the basic techniques of siegecraft established in the ancient world, notably by the Roman army, were rediscovered during the Crusades, and dominated siege warfare until the introduction of the cannon. The knowledge and experience acquired by the Crusaders heralded a new era in siege warfare. In the whole medieval military history the most striking features are undoubtedly the importance of fortified places and the ascendancy assumed by the defensive. If battles were few, sieges were numerous and often quite lengthy. Sieges were the main ingredient of any campaign in the Middle Ages, and, like a kind of chessboard tactic, the real object of military maneuvers was to deprive the enemy of his strongholds and hence of control of the countryside. The medieval fortress owed its strength not only to its construction, but also to the rather feeble nature of the attacking methods of the period. Overcoming a fortress was slow, difficult and costly. A military siege was a large-scale undertaking demanding time, comprehensive logistics and considerable organization. Besides, armies of the feudal age were very slow to move and mobiliz-able only for short periods (usually forty days a year). The success of a siege was largely due to the skills of specialists in siegecraft and the use of mercenaries who were prepared to sit out a long siege, unlike the feudal levies (vassals and peasants/ soldiers mobilized by the suzerain) who became impatient and were liable to go home at the end of their allotted time, regardless of the state of the campaign. As can be easily imagined, the length of time that a siege could last varied enormously. When facing impregnable defenses, and unless pressed for time, many medieval commanders would prefer to starve out a garrison, as no castle could hold out forever, and any stronghold would eventually succumb to starvation. But time itself was a cost. The besieging army could do nothing else and decisive victory could prove elusive. The disproportionate resources needed to take a castle in comparison to those needed to defending it was one of the key reasons for the constant rebellions of the nobility that characterized the medieval period. The nobles could often defy their monarch with impunity, at least in the short term, behind the walls of their castles. The purpose of a siege was not necessarily the destruction of the besieged. The aim could

Be to bring a rebellious vassal back to submission or to obtain political and economic compromise.

Retreating behind walls might also imply that a cost of reliance on castles was the sacrificing of offensive strategy. This was, however, not always quite true. Castle spending inevitably meant less money for the field troops, but defending a castle was not quite the same as defensive warfare. A castle could have both offensive and defensive purposes, and very few castle builders thought solely in terms of defense, as a stronghold also served as a base for attack. Castle strategy also included action and offense. First, sallies might be made against the immediate besiegers. Second, raids from the castle could threaten areas within a day’s round-trip or so. And third, the castle’s troops could be launched on a major operation against a neighboring principality. Siege warfare became the operational center of medieval warfare, not just to overcome the defense but also to prevent the fortified enemy from engaging in offense. In civil wars the focus on castles was even greater than normal because there was more emphasis on establishing and maintaining control of territory. Sieges, while difficult and expensive, were inevitable, but the business of laying siege to a castle was a highly complex and costly affair that was not undertaken lightly. The number and strength of the fortified places of medieval Western Europe demonstrate the apparent futility of many campaigns of the period. A land could not be conquered with rapidity when every district was guarded by several castles and walled towns, which would each need several months’ siege before they could be reduced. Campaigns tended either to become plundering raids, which left the strongholds alone, or to be occupied in the prolonged blockade of a single fortified place.

Entrenched behind high, thick and strong stone-walls and towers, defenders were — in theory— in an advantageous position, but high walls were not always sufficient to stop enemies. The outcome of a siege depended for a great deal on factors such as physical courage, individual bravery, logistical preparation, morale, determination and pugnacity on both sides. Throughout history there are many examples of both attacking and defending troops cracking when things went wrong. Weather conditions also played an important role; if it rained, camps and roads became quagmires, bows and hurling machines were useless, and morale could collapse. Medieval wars only took place in spring and summer. The best the defenders could hope for was to raise the price of victory to the point at which the besiegers would be unwilling to pay it.

The besiegers had several means to achieve by force the capture of a stronghold.

Intimidation and Treason

Attackers could force the defenders to surrender only by displaying their strength, and threatening terrible retaliation (pillage, fire, rape and general massacre). They might intrigue and profit of internal quarrels among the defenders and negotiate various advantages with one against the others. They could use guile and treachery by infiltrating parties disguised as merchants, pilgrims, traders or travelers in need of assistance. Once inside the friendly-posing party would open the gate to admit hidden armed comrades waiting outside. Traitors could be paid to do the same. The besiegers could also launch a surprise attack at the end of the night when guards were tired after a long watch. Sometimes the Church intervened in wartime activities. The knights defending Bedford in 1224 were excommunicated by the archbishop of Canterbury on behalf of the king. The same spiritual weapon was used at the siege of Kenilworth in 1266. So owing to intimidation, menace, negotiation, ruse, treachery, corruption, surprise, threat of eternal damnation, and often a great deal of luck, the operation could be quickly concluded.

Blockade

One way to obtain the surrender of a fortress was by using of attrition. Attackers would establish a hermetical blockade intended to isolate the place and cut all communication and supply lines. The besiegers then waited until the besieged were worn out and exhausted by hunger, isolation, sickness and discouragement. It was consequently important for the encircled garrison to have sufficient supplies and to have reliable allies coming to their rescue. Clearly, allies were of crucial importance to the beleaguered. The attrition siege was based on patience, watchfulness, logistics and time. A besieging army, however, often suffered more than the besieged from lack of shelter, periodic food shortages, and the threat of a relief force appearing in the rear. The besiegers were accommodated in one or more temporary camps, providing living quarters and some sort of military base, but there was always the danger of running short of food, and camp conditions could become unsanitary. Unhealthy food and poor sanitation could result in outbreak of devastating deceases. Besides, it was difficult to sustain the morale and discipline of idle and bored troops. The result was an endurance contest that often ended without a decisive fight. Indeed, many successful sieges were the result of negotiation, not attacking and storming.

Siege Artillery

The pressure on the besieged was increased by archers and crossbowmen deployed behind mantlets (wooden protective screens) shooting arrows and bolts, some incendiary. Fire constituted a real hazard to wooden and thatched-roof buildings inside the castle or in a town. Even more devastating were the bombardments effected by siege artillery machines. The ballista or springal was effectively a giant crossbow; it had an arm which was forced by tension and, when released, shot a missile, generally in the form of a dart or a spear. The catapult was an ancient hurling machine, a nevrobalistic or torsion weapon relying for propellent-power on twisting and releasing an elastic material like twisted rope or horsehair or sinew. The tre-buchet (also called magonel) — probably introduced during the Crusade — was another hurling machine whose propellent energy was provided by a heavy counterweight. Projectiles launched by catapults and trebuchets were mainly stones or rocks, which killed men, crushed brattices, staggered merlons, punched and weakened walls and towers, and destroyed houses and huts. Occasionally incendiary substances were also hurled, including pots of tar, quicklime, powdered sulphur and Greek fire (an evil mix of oil, pitch, quicklime and sulphur), which could cause significant ravages to wooden, thached-roof buildings.

Breaching the Wall

Blockade and bombardment were preparing actions, they proceeded the most important and most dangerous phase of the siege: the making of a breach and the assault. This phase of the siege was highly hazardous, the attackers were in a disadvantageous position, so repeated calls for negotiation and surrender were made. If they were refused the siege continued. The decisive assault could be done in two main ways: either by assaulting the top of the wall or by making a breach.

Assaulting the top of the wall could be achieved by throwing grab-dredgers fitted with rope or by using scale-ladders. An armored man climbing an unsteady 10-meter-high ladder holding a sword and a shield under a hail of arrows, stones, darts and spears was obviously vulnerable, so a much safer method of assaulting the top of the wall was by means of a beffroy or belfrey. This was a mobile wooden assault tower as high as the wall to be attacked. The tower was a strong timber frame mounted on wheels or on large wooden rolls. It was moved by means of capstans, pulleys and ropes maneuvered and winched (or simply pushed) by a party of men. The tower was rolled close to the wall; it was fitted with ladders permitting the assaulting party to climb in safety. The summit included a platform where a group of archers could shoot at the defenders; the platform also included a sort of drawbridge, which when dropped allowed attackers to set foot on the parapet for a hand-to-hand combat with the defenders. At the siege of Bothwell in September 1301, King Edward I had built a giant wooden belfrey several stories high, constructed in Glasgow, which was dragged along the rough track to Bothwell, about ten miles (16 km) away, in two days. A bridge was built over the Clyde River and finally a corduroy path was made in order to wheel the monster tower right up to the castle wall.

The attackers could also decide to destroy a section of the defensive wall by mining. Special units of experienced miners and engineers would dig an underground gallery under the wall and hollow out a space by removing masonry. As the tunnel progressed, its sides and roof were supported with wooden timbers to prevent the entire operation from prematurely crashing down on the unfortunate tunnellers. Once the required length of tunnel had been achieved, the excavation was packed with combustible material —cotton, straw brushwood and others, together with animal fat or petroleum. That was then fired after the men had scrambled to safety. The wooden props, now the only means of support for the undermined section of the defenses, would burn away and the wall above, bereft of support, would collapse. Undermining was a long, arduous and dangerous operation. It was not always successful and not always possible, obviously, if the castle was built on marshy or wet ground or on solid rock, or if its foundations were particularly strong. Only when other means had failed would recourse to the dangerous practice of mining be contemplated. In Britain, mining appeared early on with the Norman conquest, notably at William I’s siege of Exeter in 1067. The anarchy during the reign of Stephen 1135 -1154 involved considerable siege activity, notably Exeter again in 1136, and Lincoln in 1143. Henry II used mining at the siege of Bungay Castle in Suffolk in 1174. The siege at Rochester Castle, Kent, directed by King John in 1215, is one of the best-known instances of the use of mining in siege warfare.

Another means to make a breach was sapping. Stones at the base of the wall were individually picked off, dislodged and torn out until collapse of the wall. Another ancient method of making a breach was using a battering ram. The ram was maneuvered by a party of men giving a backwards and forwards movement against a gate or a masoned wall. The violent shocks worked by direct percussion but also by causing vibrations, which loosened the stones. Sapping and battering were very dangerous operations because the defenders dropped stones, threw down incendiary materials and spears and shot down arrows on the exposed attackers. In reaction a cat was constructed; a cat (also called penthouse, rat, chasteil or tortoise from the Roman testudo) was a stout, strong, movable (often wheeled) timber gallery covered with a solid sloping roof intended to protect sappers, rammers, miners, or men attempting to fill the ditch.

Assaulting

When a breach was practical the attack was launched. For the ordinary soldier, the assault was extremely hazardous, and it was not always easy to get troops to assault. Very often it required knights, leading nobles and rulers to lead from the front. As seen above, King Richard I found his death on April 6, 1199, from an infected arrow wound to his shoulder while leading the assault on the castle of Chalus in Normandy. The frontal assault in the breach was thus often led by knights who regarded it as a great honor to be among the first into a beleaguered fortress and many volunteered for this honor. At the siege of Saint-Jean-d’Acre (Palestine) in 1189, King Richard I Lionheart, him again, offered a gold piece to any man who would bring him back a stone from the walls of the city. The assault in the breach was a confused and bloody hand-to-hand battle. It was a crucial confrontation for both parties and the turning point of the siege. Individual factors, such as physical fitness and bravery, played a central role, but pugnacity was not enough against sheer numbers. A repulsed assault generally cost a lot of casualties, it could become a harrowing defeat loosening all the bonds of discipline and generating fear, panic and rabbling retreat.

Of course the tactics discussed above could be combined. At the siege of Dover Castle, Kent, in 1216 Prince Louis of France used stone-throwing machines, a battering ram and mining. Henry III did the same at the siege of Bedford in June-August 1224. Overall, the advances in offensive siegecraft were countered by subsequent advances in defensive military architecture, and the reverse.