The Middle Ages saw the development of new modes of warfare encompassing both pitched battles and siege warfare. Then as now the western world was engaged in an arms race. New weapons technology prompted new defensive technologies, for example the introduction of cross-bows led quickly to the adoption of plate armour rather than chain mail.

During the Dark Ages Christendom had largely abandoned the sophisticated techniques of Classical times, arguing that anything not mentioned in the bible was of satanic origin and that God would ensure victory for his faithful followers.

Along with the scientific advances, military techniques had been abandoned and forgotten. This affected building as well as weaponry. For example the Greeks and Romans had used iron ties to join blocks of stone together. Knowing the effects of rust they encased the iron in lead so that it did not rust, and stonework using this technique survives intact today. Medieval builders did not know about the lead protection and used iron ties that rusted, expanded and fractured the surrounding stone.

So it was with military engines like the balista and military techniques like the Romans' famous tortoise. So too, ancient techniques for making quick-setting concrete and prefabricated defences were forgotten.

To some extent the development of the Renaissance and the Enlightenment is the story of the rediscovery of ancient techniques.

Preparations for Medieval Battle
Medieval Pitched Battles
Medieval Fortifications
Medieval Siege Warfare

• Siege Towers

• Battering Rams

• Cats and Weasels

• Chemical, Biological and Psychological Warfare

• Mining: undermining castle walls

Medieval Water Supplies
Medieval Supplies and Logistics
Medieval Equipment & Weapons
Medieval Weapons Technology
Medieval Communications
Medieval Military Organisation
Medieval Women at War

Balista - a Roman artillery weapon rediscovered in the late Middle Ages

Preparations for Medieval Battles

For larger battles, planning typically consisted of a council of the war leaders, which could either be the commander laying down a plan or a debate between the different leaders, depending on how much authority the commander possessed.

Often decisions were dictated by the Church and formulated for religious rather than military reasons. This explains for example some of the worst disasters suffered by crusaders armies during the Crusades where senior clergy in command of armies routinely ignored advice from seasoned commanders.

Medieval Siege Warfare

In the Medieval period besieging armies used a wide variety of siege engines including: scaling ladders; battering rams; siege towers and various types of catapults such as the mangonel, onager, ballista, and trebuchet. Siege techniques also included mining.

Advances in the prosecution of sieges encouraged the development of a variety of defensive counter-measures. In particular, medieval fortifications became progressively stronger — for example, the advent of the concentric castle from the period of the Crusades — and more dangerous to attackers as witnessed by the increasing use of machicolations and murder-holes, as well the preparation of hot or incendiary substances. Arrow slits, concealed doors for sallies, and deep water wells were also integral to resisting siege.

Designers of castles paid particular attention to defending entrances, protecting gates with drawbridges, portcullises and barbicans. Wet skins of freshly slaughtered animals were draped over gates, hourdes and other wooden structures to retard fire. Moats and other water defences, whether natural or augmented, were also vital to defenders.

In the European Middle Ages, virtually all large cities had city walls. Carcassonne and Dubrovnik in Dalmatia are well-preserved examples. The more important cities had citadels, forts or castles inside them, often built against the city walls. Great effort was expended to ensure a good water supply inside the city in case of siege. In some cases, long tunnels were constructed to carry water into the city. Complex systems of underground tunnels were used for storage and communications in medieval cities like Tábor in Bohemia.

Attackers would try to get over the walls using scaling ladders, siege towers called belfries, and grapples. Alternatively they could try to get through the doors using a battering ram, or through the walls using heavy artillery. They might try tunnelling under the walls to gain access, but more often they would try to undermine the walls to bring them down.

In a siege one army typically attacks an enemy within a stronghold. either a castle or a fortified town. Medieval towns were generally surrounded by defensive walls, just like castles. Indeed the distinction between castles and fortified towns is often blurred. Castles were often located within fortified towns - in fact many towns grew up around existing castles - so that the castle became a sort of citadel within the fortified town.

Plan of Carcassonne - you can see the castle (chateau comtal) within the city walls. The odd external feature was a stairway down to the River Aude.

Attackers therefore often had two sets of obstacles - first the city walls, then the castle walls. This could lead to interesting complications as at Beaucaire in 1216. For months Simon de Montfort besieged Raymondet in the town, while Raymondet besieged a garrison loyal to de Montfort in the castle within the town.

Sometimes there were three sets of obstacles, because fauxburgs with their own defensive walls were often built on to the exterior of city walls, as at Carcassonne and Termes.

Besiegers had a number of techniques for gaining control of their objective - either by forcing a way in, or by forcing the besieged garrison out. Specific techniques - established since prehistoric times - include:

• breaching the walls or doorways. Attackers would use weapons to get through walls. Examples are stone throwing machines petriers such as trebuchets and mangonels); machines to knock holes in walls such as battering rams; and engines to extract individual dressed stones one by one (cats, weasels and simple picks).

• tunelling under the walls. Attackers would build mines, either to gain access to the interior or to undermine and collapse the defensive walls.

• getting over the walls. Attackers would use scaling ladders and siege engines such as large mobile wooden towers known as belfries.

• sitting and waiting. If communications between the besieged and the outside world could be cut then the defenders could be denied food supplies and sometimes water (as at Beaucaire, Carcassonne, Minerve, and Termes). This was not always possible (as for Raymondet at Beaucaire and at Montsegur). The word siege means "to sit", an indication that this was a standard technique.

• A Fifth Column. Inducing someone on the inside to assist the attackers, either by bribery or exploiting divided loyalties. They could for example open a postern gate at night. Occasionally attackers could be smuggled in to the besieged fortification to fulfil this role, as for example in ancient times in the famous Trojan horse.

• Diplomacy, threats, terror and psychological techniques. To help weaken the will of the defenders, attackers could make threats or promises, or terrorise the defenders - for example by mutilating or executing hostages, or by using throwing machines to lob fire, or human heads or other body parts, into the the fortification.

• Biological Warfare. Medieval besiegers were known to project diseased animals into fortifications with the deliberate intention of spreading disease and so weakening the garisson. I some cases it was possible to poison water supplies, though most fortifications had their own wells or water cisterns.

Until the invention of gunpowder-based weapons (and the resulting higher-velocity projectiles), the balance of power and logistics definitely favoured the defender. With the invention of gunpowder, the traditional methods of defence became less and less effective against a determined siege, giving rise to a new form of defensive structure, the star-fort.