In the period there were also improvements in the art of castle building and fortification. The normal form of a castle was a wooden building and stockade but these structures were vulnerable to fire and frail when under attack. For instance, Henry the first burnt down the castles of Brionne, Montfort-Sur-Risle and Pont-Audemer. Castles became the symbols of the wealth, status, and power of those who built them. As the number of castles and fortifications increased steadily a lord would find himself in an arms race with other lords nearby. For instance if they constructed a stone castle, so must he. As a consequence the increase in the use of military fortifications came from ‘the anxiety of of lords to maintain, consolidate, and extend their lordships.’
With the construction of physical defences came a new type of warfare, the siege. Few military campaigns in the medieval period were fought without siege to at least one stronghold. Sieges came to far outnumber pitched battles and other forms of warfare during the period such as mounted raids. For instance, Geoffrey V of Anjou conquered Normandy without a battle between 1135 and 1145. As well the later medieval period saw the appearance of crusades fought for religious purposes, as Keen notes ‘crusades were won or lost through the combination of major siege operations and pitched battle.’ The siege more often than not provided the prelude to the set-piece battle. It is clear that the possibility of death was a lot higher in battle than in siege. However the siege brought the two sides in the conflict together and was the ‘catalyst for decisive military action.’
A castle played mostly a defensive military role and responded to the menace of aggressive forces. ‘Siegecraft’ was developed to overcome defences of castles and fortifications and as a result military architects attempted to counter ‘the ever-changing arsenal of the aggressor.’ However, on the whole defences appeared to keep pace with changes in siegecraft. For example William of Holland undertook thirteen sieges between 1249 and 1251, only three of these were successful. As siegecraft evolved so too did castle designs. Therefore it is possible to link changes in military architecture with available siege techniques.
Most significantly by retreating behind physical barriers, defenders counteracted the most powerful element in any army, the cavalry or mounted knights. Knights were professional soldiers, high in the order of chivalry, bearing the most noble arms, and riding the best horses. Describing the French knights who passed through Constaninople in 1097, the Greek historian Anna Comnema observed ‘a mounted knight is irresistible; he would bore his way through the walls of Babylon.’ It was regarded impossible for mounted men to breach both walls and ditches so the ability of the knights was revoked.
An effective method of blockade was to construct counter castle. As a result a small force could survey the besieged castle, preventing the free flow of traffic to and from it. Counter castles continued to be used, for instance William the first used four counter castles to blockade Remalard in 1079. By the early twelfth century, most military commanders knew siege tactics well. Mining remained an effective tactic through undermining outer defences. Consequently, sieges in the majority succeeded, meaning military architects had to find solutions. For those who could afford it the solution was to build in stone. Most of the earliest stone castles in England and France were either ducal or royal establishments. For instance, Rouen, the White Tower in London, and Colchester were consummate examples. For the construction of significant military castles authorities and lords did not hesitate to spend large amounts. The building of the Keep at Dover between 1180 and 1190 cost nearly £4,000. Defence was of extreme military importance and records of expenditure illustrate this:
Expenses on defence works at Chateau-Gaillard 1197-1198 in sterling
Stone castles could expect to withstand siege longer since the threat from fire and physical bombardment was diminished. In addition the heightening of walls and gatehouses offered greater cover against attack on the walls. Towards the end of the twelfth century the normal duration of a siege appears to have been around four to six weeks. However if stone fortifications were well provisioned they could endure siege longer. The siege of Arundel in 1102 lasted three months and Geoffrey V of Anjou took three years to enter Montreuil-Bellay. Time was a crucial factor in a siege, since increased time either meant the chance of relieving forces coming to the assistance of the besieged or the besieged being forced to surrender on account of a lack of supplies.
Round-towered castles began to be constructed in England and France in the 1130s. Military architects began to understand the worth of circular structures from the knowledge learnt from the East through the crusades. For example at Houdan there was a round keep that was further strengthened by four round towers. With innovations being made in architecture there were also innovations in force and attacking fortifications. Around the end of the twelfth century there was a new form of siege engine, the trebuchet. It was more powerful and accurate than its predecessors were. It shifted the ‘balance of siege in favour of the besieger.’
The nature of warfare in the eleventh and twelfth centuries was altered altogether. The period is notable for its continuity in practice of attack and defence. In the main the evolution of military tactics and force influenced the advance of military architecture in design of castles and fortifications. War benefited from ‘improvements in the means of governing and administrating.’ Castle building and the progress of warfare had its foundations in a wider social change and fundamental breakdown of order. The emergence of private defence from a military threat during the period is different from other ages when the importance was placed on communal defence. Warfare advanced to become far more professional and sophisticated with huge amounts of money spent on fortifications and castles. Siege warfare became the foremost sort of conflict over pitched battles, naval assaults and mounted raids. Despite improvements in weaponry, the major tactics of siegecraft-assault, bombardment, mining and blockade did not change instead there were subtle technical changes on both sides of attack and defence that served to contradict and counter each other. However, warfare was irreversibly changed after the development of the castle and played a further significant part in later history.
Holmes George, The Oxford History Of Medieval Europe Oxford 2001, p.117
Keen M, Medieval Warfare, 1999, p.166
Holmes, The Oxford History Of Medieval Europe, p.119
Keen M, Medieval Warfare, 1999, p.164
Keen M, Medieval Warfare, 1999, p.164
Keen M, Medieval Warfare, 1999, p.165
Holmes, The Oxford History Of Medieval Europe, p.118
Contamine P, War in the Middle Ages, 1984, p.110
Keen M, Medieval Warfare, p.175
Contamine P, War in the Middle Ages, p.115