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Other than simple towers, all castles have surrounding defensive walls.

as the Romans knew, simple walls can be difficult to defend because the defenders need to be able to fire upon all areas outside but near the walls. The Roman solution was to construct towers at intervals along the walls. These towers provided covering fire for the walls. This same solution was used in Medieval times.

Medieval builders used a number of techniques to strengthen walls, for example building them thicker at the base to prevent undermining (taluses), and cutting the stones in such a way as to be able to withstand high impact projectiles (bossing).

Castle walls were also used to help defences in other ways - for example walkways on top of the walls (chemins de rondes) allowed defenders to move quickly around the castle defences. Battlements (crenellations) protected them for enemy fire. Simple battlements could support further defences such as hourdes in times of trouble, later to be replaced by permanent stone machicolations.

Walls were often provided with arrow loops and later by gun ports (cannoniers) to enable defenders to fire on the enemy in relative safety.

The curtain walls at the Chateau Comtal with wooden Hourds, inside the Cité of Carcassonne


The Inner curtain walls at Carcassonne


Not only castle needed protection. In areas where the Church was particularly unpopular its buildings were often build like castles. This is the Cathedral at Albi in France.

Curtain Walls (Courtines)

A curtain wall or courtine is a type of defensive wall forming part of the defences of medieval castles and towns.

The curtain wall surrounded and protected the interior courtyard, or bailey, of a castle. These walls were often connected by a series of towers or mural towers to add strength and provide for better defense of the ground outside the castle, and were connected like a curtain draped between these posts.

Additional provisions and buildings were often enclosed by such a construction, designed to help a garrison last longer during a siege by enemy forces.

With the introduction of star forts (trace italienne fortification) the height of the curtain walls was reduced and additional outworks such as ravelins and tenailles were added beyond the ditch to protect the curtain walls from direct cannonading.

Coutain Wall at Carcassonne

Battlements & Crenellations


Castle walls were often crenelated, that is to say provided with projections called merlons. These merlons provided protection for defenders while allowing them to shoot from the gaps between. Some merlons were provided with their own arrow slits, providing the defenders with even more protection (as shown near right)

A battlement (also called a crenellation) in defensive architecture such as that of city walls or castles, comprises wall) in which portions have been cut out at intervals to allow the discharge of arrows or other missiles. These cut-out portions form crenels (also known as carnels, embrasures, loops or wheelers).

The solid widths between the crenels are called merlons (or cops or kneelers). A wall with battlements is said to be crenelated or embattled. Battlements may have protected walkways (chemin de ronde) behind them.

The term originated around the 14th century from the Old French word batailler, "to fortify with batailles" (fixed or movable turrets of defence).

Battlements have been used for thousands of years; the earliest known example is in the palace at Medinet-Abu at Thebes in Egypt, which allegedly derives from Syrian fortresses. Battlements were used in the walls surrounding Assyrian towns, as shown on bass reliefs from Nimrud and elsewhere. Traces of them remain at Mycenae in Greece, and some ancient Greek vases suggest the existence of battlement. Battlements can be seen in the Great Wall of China.

Romans used low wooden pinnacles for their first aggeres (terreplains). In the battlements of Pompeii, additional protection derived from small internal buttresses or spur walls against which the defender might place himself so as to gain complete protection on one side. In the battlements of the Middle Ages the crenel comprised one-third of the width of the merlon: the latter, in addition, could be provided with arrow-loops of various shapes, depending from the weapon to fire. Late merlons permitted fire from the first firearms.

From the 13th century the merlons could be connected with wooden shutters that provided added protection when closed. The shutters were designed to be opened temporarily to allow fire against attackers, and closed during reloading.

The term embrasure, in military architecture, refers to the opening in a crenellation or battlement between the two raised solid portions or merlons, sometimes called a crenel or crenelle. The purpose of embrasures is to allow weapons to be fired out from the fortification while the firer remains under cover. The splay of the wall on the inside provides room for the soldier and his equipment, and allows them to get as close to the wall face and arrow slit itself as possible (see right). Excellent examples of deep embrasures with arrow slits are to be seen at Aigues-Mortes and Château de Coucy, both in France.

By the 19th century, a distinction was made between embrasures being used for cannon, and loopholes being used for musketry. In both cases, the opening was normally made wider on the inside of the wall than the outside. The outside was made as narrow as possible (slightly wider than the muzzle of the weapon intended to use it) so as to afford the most difficult possible shot to attackers returning fire, but the inside had to be wider in order to enable the weapon to be swiveled around so as to aim over a reasonably large arc.

A distinction was made between vertical and horizontal embrasures or loopholes, depending on the orientation of the slit formed in the outside wall. Vertical loopholes—which are much more common—allow the weapon to be easily raised and lowered in elevation so as to cover a variety of ranges easily. To sweep from side to side the weapon (and its firer or crew) must bodily move from side to side pivoting around the muzzle, which is effectively fixed by the slit.

Horizontal loopholes, on the other hand, facilitate quick sweeping across the arc in front, but make large adjustments in elevation very difficult. They were usually used in circumstances where the range was very restricted anyway, or where rapid cover of a wide field of arc was preferred.

Another variation had both horizontal and vertical slits arranged in the form of a cross, and was called a crosslet loop or an arbalestina since it was principally intended for arbalestiers (crossbowmen). In the sixteenth and seventeenth centuries, after the crossbow had become obsolete as a military weapon, crosslet loopholes were still sometimes created as a decorative architectural feature with a Christian symbolism.

Embassure at Caen




Bossed stones are cut building stones which are left rough on the external side.

Historians used to debate why builders did this. One theory was that it saved money since there was less finishing for the stone mason. Another was that it gave an impression of strength.

Now we know. According to several texts on catapults, bossing was a means of strengthening a wall against heavy shot. The projection dispersed the energy of the stone shot and prevented a direct energy transfer to the wall. Its use pre-dates Rome.

After the development of firearms, builders switched to other materials, such as brick, which absorb even greater impacts.

The technique is similar to the modern use of spaced armour on tanks

Bossing around an arrow slit at Carcassonne


Batters or Taluses or Plinths


Talus at Carcassonne

A batter or talus is a sloping face at the base of a fortified wall.

Defensive walls were often built thicker at the bottom. This made it more difficult for attackers in three ways.

First, attackers would have a more diffult job in breaking through or undermining the wall because of its great mass.

Second, conventional siege equipment is less effective against a wall with a talus. Scaling ladders may be unable to reach the top of the walls and are also more easily broken due to the stresses caused by the angle they are forced to adopt. attackers would have greater difficulty in moving siege engines up against a talused wall - to reach the top of the wall they required not only height but a substantial overhang. Siege towers cannot approach closer than the base of the talus, and their gangplank may be unable to cover the horizontal span of the talus, rendering them useless.


Third, defenders are able to drop rocks over the walls, which will shatter on the talus, spraying a hail of shrapnel into any attackers massed at the base of the wall.

The talus is feature of some late medieval castles, especially prevalent in crusader constructions. There is a spectacular talus at Krak - shown here on the right.



Talus at Carcassonn
A massive talus at Krak des Chevaliers

Coca, Segovia, Castile-Leon, Spain

with impressive taluses

Castel Nuovo (or Maschio Angioino), Piazza Castello, Naples, Italy with spectacular batters (or taluses) on the round corner towers

Palacio de la Aljafería (The Aljafería Palace), Zaragoza, Spain with a spectacular talus / bastion.


Chemins de Rondes


chemin de ronde (French, "round path" or "patrol path") is a raised protected walkway behind a castle battlement.

In early fortifications, high castle walls were difficult to defend from the ground. The chemin de ronde was devised as a walkway allowing defenders to patrol the tops of ramparts, protected from the outside by the battlements or a parapet, placing them in an advantageous position for shooting or dropping projectiles.


Chemin de Ronde



Hourds are defensive wooden structures built onto the top of a defensive wall. They would then be covered in the wetted skins of freshly slaughtered animals to minimise the risk of attackers being able to set fire to them.

Hourdes could be assembled when trouble threatened - in times of peace they were not needed.

Walls built to bear hourdes have a characteristic row of double holes ready to take the supporting wooden beams.

Hourdes at Toulouse under construction

Hourds have been reconstructed on the Chateau Comptal at Carcassonne as shown on the right

The purpose of a hoarding was to allow the defenders to improve their field of fire along the length of a wall and, directly downwards to the wall base. They were wooden structures build on the top of walls. Like all defensive wooden structures they were covered in fresh animal skins to keep them fireproof.

In peacetime, hoardings could be stored as prefabricated elements. In some castles, construction of hoardings was facilitated by putlog holes that were left in the masonry of castle walls.

Some medieval hoardings have been reconstructed - including the Chateau Comptal at Carcassonne.

Hourds were later replaced machicolations, which were an improvement on hoardings, not least because masonry does not need to be fire-proofed. Machicolations are also permanent and siege-ready.

Internal View of Hourdes at Carcassonne

We have a faint reminder of hourds in our modern hourdings - now used for advertising.

Internal View of Hourdes at Carcassonne
hourdes at Carcassonne
post hole for hourdes at Carcassonne
hourdes at Carcassonne


hourdes at Carcassonne


Hourds at Carcassonne
Internal View of Hourdes at Carcassonne
Hourdes at Carcassonne seen from below
hourdes at Carcassonne
Hourdes at Carcassonne - viewed from inside

Machicolations (Machicoulis)


A machicolation is a floor opening between the supporting corbels of a battlement, through which stones could be dropped on attackers at the base of a defensive wall. A machicolated battlement projects outwards from the supporting wall in order to facilitate this.

The design was developed in the Middle Ages when the European crusaders returned from the Holy Land.

The word derives from the Old French word *machecol, mentioned in Medieval Latin as machecollum and ultimately from Old French macher 'crush', 'wound' and col 'neck'. The word Machicolate is recorded in the 18th c. in English, but a verb machicollāre is attested in Anglo-Latin. A variant of a machicolation, set in the ceiling of a passage, was known as a murder-hole.

Machicolations were more common in French castles than their English couterparts, and when used in English castles they were usually restricted to the gateway as at 13th-century Conwy Castle.

Machicolations were later used for decorative effect with spaces between the corbels but often without the openings, and subsequently became a characteristic of the many non-military buildings, for example, Scottish baronial style, and Gothic Revival architecture of the 19th and 20th centuries.

Maciolations are in effect stone versions of hourdes. They represent an additional level of sophistication and expense. Like hourdes they enabled defenders to shoot at and drop things on their attackers, while minimising the risk of danger themselves. The great advantages were

  • Machicolations were permanent features. They did not need to be constructed in anticipation of attack. They were always ready.
  • Unlike hourdes, they could not be set on fire
  • They were stronger than hourdes and would withstand crossbow quarrels and even stones hurled by stone throwing siege engines.
  • They looked imposing - a psychological benefit against attackers who had no such defenses


Where the expense was too great for full scale machilations around a wall, a cheaper alternative was to build them just over weak spots like doors and gateways. This is the origin of the brattice - see below.



Abbazia di San Nilo, Grottaferrata, Rome

with extraordinary machicolations

The Brattice (Bretèche)


a brettice is a structure projecting from a wall which enables a defender to fire on attackers while remaining in relative safety. It has holes in the floor and usually arrow loops or gun ports in the sides. It is a sort of miniature macicalation, invariably placed to defend a specific weak point such as a doorway.

In apearance brattices can look very like latrines - but latrines are never placed over doorways!

A Brattice at Carcassonne (missing its front and side walls)


A Brattice at Carcassonne.


A Brattice at Carcassonne - this one is later than the one above.
It has a gun port at the front rather than an arrow slit.


A Brattice at Carcassonne.
Note the adjacent arrow loops


A Brattice at Carcassonne.
Note the adjacent arrow loops



Meurtrieres are holes designed for defenders to kill attckers. Projectiles can be thrown or shot at the attackers while the defenders remain relatively safe.

They can conveniently be divided into two classes: holes in floors "Murder Holes" (for dropping dangerous substances or shooting at attackers) and holes in walls, such as arrow loopholes, used for shooting projectiles. For arrows they are called arrow slits or arrow loops (archeres) and for guns they are called cannoniers (canoniers)


The woman who threw the stone that killed Simon de Montfort at Toulouse


Murder Holes


Attackers would naturally go for a castle's weak points, and the these weak points generally included entrances. For this reason entrance gates were heavily reinforced, often provided with extensive defensive works called barbicans.

Typically the attackers would need to pass a number of obstacles, and the defenders would try to pick the attackers off as they were occupied overcoming these obstacles.

Typically these obstacles would include steep inclines, ditches or moats furnished with draw bridges, and port cullises often a series of purtcullises.

As attackers were finding a way through a door or portcullis they would be shot at by the defenders. A simple hole in the floor of the structure over a gateway provided a convenient way not only to shoot attackers, but also to drop things on them.

Looking Up at a Murder Hole
in the Narbonne Gate at Carcassonne

Attackers selected the least pleasant possible items to throw on their enemies. In the popular imagination this was invariably boiling oil, but there does not appear to be a single documented insatnance of oil being used. We do however know of boiling water, molten lead, and even heated sand (all of which could penetrate armour more easily than other weapons). Other favoured materials included large stones.


Murder hole in the Cite entrance of the Chateau Comptal at Carcassonne

A Round Murder Hole seen from above





Attackers approaching an external gateway would be faced by a series of obstacles.
A strong wooden gate would be set behind a port cullis.
In this photograph a portculis would drop between the second and thiird arch.


This is the view looking up. The slot at the botto is for a port cullis.
The slot at the top is a type of murder hole.

Inside the room beyond the murder hole, port cullis and door
is another murder hole set into the centre of the vaulted cieling.


Arrow slits or loop-holes (archeres)


An arrowslit is a thin vertical aperture in a fortification through which an archer can launch arrows.

It is alternatively referred to as an arrow loop, loop hole, or archere, and sometimes a balistraria.

The interior walls behind an arrow loop are often cut away at an oblique angle so that the archer has a wide field of view and field of fire. Arrow slits come in a remarkable variety. A common form is the cross. The thin vertical aperture permits the archer large degrees of freedom to vary the elevation and direction of his bowshot but makes it difficult for attackers to harm the archer since there is only a small target to aim at.

Arrow slits can often be found in the curtain walls of medieval battlements beneath the crenellations.

The invention of the arrowslit is attributed to Archimedes during the siege of Syracuse in 214–212 BC. Slits "of the height of a man and about a palm's width on the outside" allowed defenders to fire bows and scorpions (an ancient siege engine) from within the city walls.

Although used in late Greek and Roman defences, arrowslits were not present in early Norman castles. They are only reintroduced to military architecture towards the end of the 12th century, with the castles of Dover and Framlingham in England, and Richard the Lionheart's Château Gaillard in France.

In these early examples, arrowslits were positioned to protect sections of the castle wall, rather than all sides of the castle.

In the 13th century, it became common for arrowslits to be placed all around a castle's defences.

Arrow loophols at Carcassonne - outside

In its simplest form, an arrowslit was a thin vertical opening, however the different weapons used by defenders sometimes dictated the form of arrowslits. Openings for longbowmen were usually tall and high to allow the user to fire standing up and make use of the 6 ft (1.8 m) bow. Those for crossbowmen were usually lower down as it was easier for the user to fire whilst kneeling to support the weight of the weapon.

It was common for arrowslits to widen to a triangle at the bottom – called a fishtail – to allow defenders a clearer view of the base of the wall.]

Immediately behind the slit there was a recess called an embrasure; this allowed a defender to get close to the slit without being too cramped.

The width of the slit dictate the field of fire, but the field of vision could be enhanced by the addition of horizontal openings; they allowed defenders to view the target before it entered range.

Usually, the horizontal slits were level, which created a cross shape, but less common was to have the slits off-set (called displaced traverse slots) as in the remains of White Castle in Wales. This has been characterised as an advance in design as it provided attackers with a smaller target, however it has also been suggested that it was to allow the defenders of White Castle to keep attackers in their sights for longer because of the steep moat surrounding the castle.

Arrow loophols at Carcassonne - inside



When an embrasure linked to more than one arrowslit – in the case of Dover Castle defenders from three embrasures can shoot through the same arrowslit – it is called a "multiple arrowslit".

Some arrowslits, such as those at Corfe Castle, had lockers nearby to store spare arrows and bolts; these were usually located on the right hand side of the slit for ease of access and to allow a rapid rate of fire.

Arrow loops needed to provide cover as a close as possible to the walls. This is one reason why towers were used along the defensive walls - they provided a way to defend the neighbouring walls.

Arrow slits were angled in such a way that they could provide cover as close as possible to the foot of the wall. Archers could achieve angles as small as 5° from the vertical.


A typical Arrow Loophole

Arrow slits were not always regarded with romanic affection. In the nineteenth century many castles were used at workshops, stores and peasant accommodation. To keep out the weather holes like arrow slits would often be blocked up.

On the right is an example from Carcassonne, where the slit has been filled with Toulouse brick, preserving the outline of the original hole.





Arrow loophols at Carcassonne
External view

Arrow loophols at Carcassonne
External view



Views of a typical arrow loop - external, side and internal elevations. Although offering a small opening on the outside, arrowloops are much larger constructions on the inside. As the defenders need to fire downwards, the external loophole is rather lower than the archer's internal niche.

Arrow loophols at Carcassonne - Internal view

An example from Aigues Mortes
Viollet le Duc's impression of a crossbowman looking out through an Arrow loophols at Carcassonn

Arrow loophols at Carcassonne - Internal view


Arrow loophols - Internal view


Arrow loops needed altering in later times to allow their use by firearms.

Late Medieval and Early Renaissance castles have cannoniers (for guns) rather than archeres (for arrows).

The hole is just large enough to pass through an arquebus and the vertical slot for sighting it.





Slighting Castles


Often, once a castle was taken, it would be occupied by its new masters and it would continue its function of holding down a strategically important area.

Occasionally this was not done. Perhaps the castle could not be held because forces were needed elsewhere (as happened during the Cathar Wars), or because it was untenable with a large hostile population (again as happened during the Cathar Wars). Perhaps the castle was taken only for puniutive reasons (as also happened during the Cathar Wars, Spanish incursions, and during the Hundred Year's Wars). Or perhaps the strategic importance diminished, as for Carcassonne and her five sons after the border between France and Spain was moved back under the Treaty of the Pyrenees in 1649.

During the English Civil War, Helmsley Castle was besieged by Sir Thomas Fairfax.. Sir Jordan Crosland held it for the King for three months before surrendering. Parliament ordered that the castle should be slighted to prevent its further use and so much of the castle's walls, gates and the eastern half of the east tower were destroyed (see right). However the mansion was spared.

In each case there was good reason for destroying the castle before leaving it and allowing it to be re-occupied. But destroying a castle is not easy. Generally it was good enough to do just enough damage to make it not worth while for anyone to repair it. To damage a castle in this way is to "slight" it. By analogy we talk about slighting people too - not desroying them but damaging them.

The castle at Beaucaire was slighted by Richelieu in 1632, and so were the "Five Sons of Carcassonne", five Royal castles (Termes, Aguilar, Peyrepertuse, Queribus and Puilaurens) strategically placed to defend the old border against Aragon. In 1652 Richelieu ordered the castle at Termes to be abandoned and slighted. The walls were destroyed by a master mason from Limoux, using explosives, between 1653-1654.

Traditionally, a strategy of slighting fortifications was often adopted in warfare by the side which had the support of the ordinary population, against an opponent which may have been militarily strong but did not have popular support, often an alien invader. Examples of forces who adopted this strategy include the Bruce brothers in the Scottish Wars of Independence, the Mamelukes in their wars against the Crusaders, and the Parliamentary side in the English Civil War.

The Slighted Keep of Helmsley Castle




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