Site hosted by Build your free website today!

Siege Warfare

The Art of Offence and Defence

By Stephen Francis Wyley 


This article was first presented as a lecture at the 1989 Australasian Medieval Conference (Maldon, Victoria).

The development of fortification has always been partly dictated by the type of siege tactics and equipment used against them. The basic techniques of siege craft established in the ancient world continued to dominate siege warfare until the introduction of the cannon, some techniques were still employed in this day and age.

Basically, an attacker confronted by a wall has five options, if you include retreat. The are as follows;

1) Blockade – to cut off supply of provisions and re-enforcements to the fortification.
2) Escalade – to attack the wall using scaling ladders and or siege towers.
3) Breach – to cause a breach in the wall by attacking the masonry of the wall using siege equipment (bore, ram, mouse).
4) Mining – to cause a breach in the wall by undermining it, or combination of escalade, breaching and mining.
5) Retreat – to retreat was also an option when attacked or threatened by a relieving force.
(6) trickery- to gain access by means of ruse or treason.


An attacker may take the first option and wait for the garrison to surcome to disease, starvation, thirst or boredom. Such tactics could not be relied upon because if the garrison’s larders were well stocked and the supply of fresh water was adequate, the besieging force had a while to wait, during which the besiegers had to survive on what they brought with them or off the surrounding country side (not a good option if the besieged had implemented a scorched earth policy).


Escalade was the most direct and also the most dangerous of the options. The action consisted of the attacking forces moving forward from their lines to the base of the wall where they set the ladders against the wall, and then scaled them to engage the defenders in had to hand combat. All the while being harassed by defenders trying to push the ladders away, throwing missiles and loosing arrows and bolts at them.

Eventually, if the attacking force was luck enough they made ground on the wall top by being continually reinforced from below, they could force their way into the castle, opening the gate for the rest of their companions left waiting outside. This was not always successful option due to the fact that the defending garrison had their own ideas on the matter.

Even if the attackers did manage to gain control of the battlement, any further advancement was usually hindered by the fact that the defenders could retreat to the towers punctuating the curtain wall thus isolating the wall walk, and continue the defence from the adjacent towers. The attackers would find it a difficult position to hold, being harassed from the inner works as well as the flanking towers, and that any siege equipment used to breach the towers would probably have to be brought up the ladders, not to mention the exposed nature of the position.

A siege tower was a much more efficient way of attacking a wall top position, allowing a large fighting force to gain the wall top in a short period of time in comparative security compared to an escalade.

A siege tower usually consisted of a wooden tower on wheels or rollers, equipped with ladders, stages and drawbridges at the top. The exterior could be clad in plank or hides to ward against missiles and incendiary devises. The tower was built to the height of the wall, filled with fighters, and then pushed into place next to the wall, then the drawbridge on the top deck was lowered and the fighters rush forwards to engage the defenders, while reinforcements moved upwards from the lower stages adding to the weight of the initial assault. Siege towers often were defended by archers shooting through arrow slits or crenels, and also equipped with sally ports and even a ram in some cases.

The Siege tower could easily be countered by surrounding the fortification with a ditch or a moat. The attacker overcame the problem by filling in the ditch with bundles of brushwood, rocks and soil, producing a causeway towards the wall. Defenders could also dig pits covered with brushwood and earth outside the walls to counter an attack by siege tower, which would either be stopped or would topple over when they ran into them. Defenders would also be retaliating during the advance of the siege tower itself and its occupants, and the forces moving the siege tower into place.

Breaching the walls.

The wall masonry could be attacked directly baking a breach through which the assailing forces could enter the fortified perimeter. One way of causing a breach in the stonework was to use a heavy iron tipped ram to pound the wall until it gave way.

The operators of the ram were under attack most of the time while they were at work from above, the defenders hurled all manner of objects and materials in an attempt to impede the work. So it was always wise to employ a penthouse or ‘cat’, a wooden shelter protected by rawhides or iron plants. The ram itself, was slung or chains beneath the penthouse’s roof, once the penthouse was set in place against the wall, the ram could be set swinging against the masonry. Another device which could also be used under the penthouse was called a ‘mouse’ or a ‘bore’, which was a sharp tipped lever which was used to pick out the mortar between the stones and them eventually the stones themselves, until a breach was made.


Mining was one of the best ways of breach a wall, though it was a slow process. A tunnel was dug from the besieger’s lines to under the wall to be breached, once under the foundation, the tunnel was extended laterally along the wall front. The chamber was supported by timbers and once it was of a sufficient size, it was filled with combustible material and then set a light. Once the wooden props had burned away the section of wall above was thus unsupported and gave way falling into the cavity created by the mining, producing the required breach.

Mining could be obstructed by making the base of the walls wider (eg. Spurs, talus, etc.) making the wall more stable. The only active counter measure to mining was counter mining. A mine was excavated from inside the castle to intercept the incoming mine. The combat which occurred when the two mines met in those dark, cramped conditions was on of the most horrific aspects of early siege warfare.

Siege Engines.

In addition to the direct methods of assault, there was the engines which acted as artillery which were capable of casting missiles over the walls of fortifications and causing significant destruction. There were two basic types; the mangonel, which was a catapult; and the ballista, a massive crossbow.

It was not until the Middle Ages that a new siege engine were developed, the trebuchet. This consisted of a long pivoted arm. At the front, short end, a basket of stones acted as a driving force, at the longer end was leather sling. To operate the device, the long end of the arm was pulled down against the weight of the stones and missiles were placed in the sling. This was usually a stone but artillery men have always had a mordant sense of humour, and dead horses, corpses and even live prisoners found their way into the sling at various times. The arm was released, the counterweight causing the front end to go down and the long arm to fly through the air and discharge the contents of the sling in a high arc which carried the missile over the defences.

Although engines were often used to batter walls by throwing massive stones against them, their prime purpose was to bombard the interior of a defended work or town so as to wreck buildings, kill or injure and demoralize the occupants. Incendiary missiles such a red hot stones or jars of ‘Greek fire’ were also used. Siege engines were also utilised by the defenders against the attackers, the advantage of height being in the defenders favour. Introduced by the Greeks and perfected by the Romans, siege engines continued to be used until well into the gun powder era, since they had virtues of being cheap and easy to make ane were much more destructive than early cannon.


To Conclude, siege warfare was a time consuming affair which pitted the strengths of military architecture against the destructive effects of siege craft. Overall, the advances in siege craft were countered by subsequent advances in military architecture, and the reverse.

S.Wyley 18/3/89.


Allen Brown, R., English Medieval Castles, London, 1954.
Allen Brown, R., Castles - A History and Guide, Dorset, 1985.
Anderson, W., Castles of Europe, Hertfordshire, 1984.
Barrucand, M. & Bednorz, A., Moorish Architecture in Andalusia, Köln, 1992.
Brice, M.H., Forts and Fortresses, London, 1990.
Brice, M.H., Stronghold: A History of Military Architecture, London, 1984.
Bottomley, F., The Castle Explorer’s Guide, London, 1979.
De Breffney, B., Castles of Ireland, London, 1977.
Duby, G., France in the Middle Ages 987 - 1460, USA, 1991.
Edwards, R.W., The Fortifications of Amenian Cilica, Washington D.C., 1987.
Fass, V., The Forts of India, London, 1986.
Forde-Johnston, P., Hadrian's Wall, London, 1977.
Fry, P.S., British Medieval Castles, London, 1974.
Gebelin, F., The Chateaux of France, London, 1964.
Gravett, C., Medieval Siege Warfare, London, 1990.
Guilbert, G., Ed., Hill-Forts Studies, Leicester, 1981.
Hinago, M., Japanese Castles, Japan, 1986.
Hogg, I., The History of Fortification, London, 1981.
Hughes, Q., Military Architecture, London, 1974.
Johnson, A., Roman Forts, London, 1983.
Johnston, P., The National Trust Book of British Castles, London, 1979.
Johnston, P., Castles of England, Scotland and Wales, London, 1989.
Kennedy, H., Crusader Castles, Cambridge, 1995.
Knightly, C., Strongholds of the Realm, London, 1979.
Lawrence, T.E., Crusader Castles, London, 1986.
Manley J., Atlas of Prehistoric Britain, London, 1989.
Minney, R.J., The Tower of London, 1971.
Muller, J., Treatise of Fortifications, 1746. Reprinted Ontario, 1968.
Oman, C., Sir, Castles, New York, 1978.
Ross, S., Scottish Castles, Moffat, 1990.
Sorrel, A., British Castles, London, 1973.
Smith, Capt. G., An Universal Military Dictionary, 1779. Reprinted Ontario, 1969.
Tabarelli, G.M., Ideal and Fortified Cities of the Renaissance, Arts, Arms and Armour, An International Anthology Volume 1, 1979 - 80, Switzerland, 1979.
Toy, S., A History of Fortifications from 3000 BC to AD 1700, London, 1955.
Tsangadas, B.C.P., The Fortifications and Defense of Constantinople, New York, 1980.
Tuulse, A., Castles of the Western World, Austria, 1958.
Warner, P., Sieges of the Middle Ages, London, 1968.
Weissmüller, A.A., Castles From the Heart of Spain, London, 1967.


Castles on the Web

 Site O is a group of people from around the world that share an interest in fortifications and artillery. Some are authors on the subject, some are connected with Universities and teach it and others are simply fascinated with it.

Other web pages on fortifications by the Author.

A Dictionary of Military Architecture
An Aerial View of Masada
Anglo-Saxon Burhs
Bibliography of Military Architecture
David's Tower, Jerusalem
Drawings of Aspects of Military Architecture
Jerusalem from the Mount of Olives
More Pictures of the Theodosian Land Walls
Shiro, A Japanese Castle
The Walls of Ankara
The Defences of Constantinople
The Town Walls of Conwy
What is a Castle?

Sign My GuestbookGuestbook by GuestWorldView My Guestbook

This page was last updated on the 7th January 2002

There have been Visitors to this page
Return to the top of the page Return to Sven's index page

Copyright © Stephen Francis Wyley 2000 - 2002