The Castle

The Development of Castles Over Time

Jonathon Davies, Going Postal
Neuschwanstein Castle in Bavaria, Germany. Built by Ludwig II.

I love castles and have always found their development and changing functions fascinating. They show social, military and political history. They are a physical representation of the past, and yet many of them are still in use today in some way. So let’s have a look in a bit more detail. I have included some tweets from a few of my favourite Twitter accounts, which are worth a follow for your castles fix.

Reasons For Castles

The most obvious use of a castle or fort is protection. From early on people desired a defensible position to keep them, their families and property safe. This became especially true when we switched from hunter gathering to farming. No point settling down in a nice spot, pouring all your hard work and effort in to building a settlement and cultivating the land if some buggers can sweep in, rob everything and kill you. As time moved on more complex political systems developed and castles became a seat of power. What better way to show off than an enormous stone castle, built at great expense, looming over the peasantry while most people built with wood and manure? It was a way of reminding everyone who was boss.

Castles proved great for keeping control. You could garrison soldiers there who were secure behind the walls. If the peasants were revolting you could turn them loose for some fun and games until order was restored. Big thick stone towers and keeps also made wonderful dungeons to lock up criminals or indeed political rivals.  For example Robert, Duke of Normandy was imprisoned in Cardiff Castle after a failed attempt to take the throne from Henry I. The keep was the most secure part of the castle acting as a last fall back position (retreat to their safe space). The Tower of London is the most famous example, being the stone keep inside the castle William I built in London. Castles strategically placed near roads and rivers could control the movement of people and collect tolls. Taxes could be collected from the populations of towns with a castle in or near them.

Siting Your Castle

linked to the above, where you built your castle was important. As mentioned control of roads was important for tolls and population movements. Also key was control of the routes armies would march along. The same was true of being near or on a river. Tolls could be collected and ships stopped. Rivers also provided a vital water supply, especially as the castle may come under siege. Rivers could be used to transport troops and also to resupply the castle with food, fuel and equipment. Water defences such as moats could be added to make the castle even harder to take.

Being near a town or local villages helped. Farmers or markets provided food, labourers could be found to work, along with blacksmiths, farriers, etc. Some castles were placed on hills or mountains. This gave the advantage of being able to see enemies coming from a long distance. Added to this was the difficulty of laying siege to and attacking a castle going uphill. Men got tired and moved more slowly, making easier targets for archers, who also had a greater range due to elevation. Shooting a bow uphill curtails the range and power of the shot. The same goes for siege weaponry such as catapults and trebuchets.

Jonathaon Davies, Going Postal
Castles in hard to reach places were difficult to attack.

Being somewhere quite inaccessible, and with a narrow approach meant that your castle would be harder to attack. Only a certain number of attackers could approach at any one time and the castle would be difficult to surround. Putting your castle in the middle of a forest may not be the best idea as an enemy army could approach under cover, and have plenty of material to build siege weapons with and make arrows for ammunition. It was common practice to clear the area around a castle to allow clear lines of sight and to ensure no cover or assistance was given to those trying to scale the walls.

Early forts

The welsh word for castle or fort is “caer.” This is useful when looking at place names as it tells you there is or was a castle there. For example Caernarfon, Caerffili (welsh spelling), Cardiff is Caerdydd and so on. There is an area of Cardiff called Caerau. Here the remains of an iron age hill fort were found. South Wales at this time was home to the Silures tribe, and evidence of occupation goes back 2,500+ years. The fort consists of three large ramparts with ditches and two entrances. The ramparts curve around to provide a view of the approach to the fort. Caerau Hillfort is the third largest Iron Age hillfort in Glamorgan enclosing 5.1 hectares, about the size of four football pitches. There is evidence of cultivation inside the fort in the form of furrows.

Jonathaon Davies, Going Postal
The remains of Caerau hill fort today.

Photo by John Lord at

The reason for the emergence of hillforts in Britain, and their purpose, has been a subject of debate. It has been argued that they could have been military sites constructed in response to invasion from continental Europe, sites built by invaders, or a military reaction to social tensions caused by an increasing population and consequent pressure on agriculture. The dominant view since the 1960s has been that the increasing use of iron led to social changes in Britain. Deposits of iron ore were located in different places to the tin and copper ore necessary to make bronze, and as a result trading patterns shifted and the old elites lost their economic and social status. Power passed into the hands of a new group of people. Archaeologist Barry Cunliffe believes that population increase still played a role and has stated “the forts provided defensive possibilities for the community at those times when the stress of an increasing population burst out into open warfare.-Infogalactic


Along came the Romans (with almost exclusively black troops according to the BBC). They invaded, killed lots of people, took slaves and imposed taxes. Obviously the locals were not best pleased about this, and the Romans needed some sort of protection so they were not all murdered in their sleep. They also needed a way to control the locals. The Welsh proved troublesome (some things never change) and Caratacus-known as Caradog-further inflamed things when he led a rebellion. The Silures defeated a Roman force sent against them in 52 A.D. So the Romans set up legionary bases. The one in South Wales was known as Isca, or Usk, giving it’s name to the town and the river. Later it was moved to Caerleon. Translated this means castle of the legion.

Jonathaon Davies, Going Postal
The amphitheatre at Caerleon. This would have provided “entertainment” for the troops.

They also set up forts within a days march of each other. One of these was at Cardiff. As mentioned it was near a river, and the Romans helpfully provided roads. The fort was almost square in design, approximately 635 feet (194 m) by 603 feet (184 m) large, constructed from limestone brought by sea from Penarth. The fort’s irregular shape was determined by the River Taff that flowed along the west side of the walls. The sea would have come much closer to the site than is the case in the 21st century, and the fort would have directly overlooked the harbour. This Roman fort was probably occupied at least until the end of the 4th century.-Infogalactic

Motte and Bailey Castles

The Roman Empire eventually collapsed as all European empires always do. Having allowed free movement to the tribes such as the Visigoths, Rome was sacked by Alaric I (his tribe had arrived as refugees). Many of their old forts were abandoned (during Saxon times fortified towns were built, known as burhs. These were mainly to fend off Viking raids. They are generally not classed as castles). Later the Normans invaded, 1066 and all that. The Normans were faced with the same challenges as the Romans. They were vastly outnumbered by a recalcitrant population, needed to stamp their authority on them and control their new lands. One way of doing this was the feudal system. Another, linked to this, was to build castles. The king, William I, initially built castles. Trusted nobles were then given land to secure territory and administer it. Barons would build their castles on these sites. Later so did more minor nobles. You may notice there are many castles in Wales and this was no accident. Marcher Lords were given free reign and lands for campaigning in Wales, holding and expanding the frontier.

Jonathon Davies, Going Postal
The motte at Cardiff Castle. The original wooden keep was replaced with stone at a later date.

The first of these castles were made from wood and known as Motte and Bailey. The motte was the mound of earth a wooden keep was built on. The bailey was the area enclosed by a wooden palisade. One of these was built in Cardiff on the side of the old Roman fort. In the picture you can clearly see the motte surrounded by a ditch. Local would be coerced in to building it, with nearby woods or houses providing material. The advantages of this was that they were quick, easy and cheap to build. The motte proved difficult to attack and the keep at the top provided effective cover and a lookout position.

Stone Keep Castles

Those attacking castles were quick to realise the best way to attack a wooden castle was to burn the buggers out with fire. Hence flaming arrows became a favoured method. This was part of a long lasting arms race throughout Europe, the Middle East and indeed the world between castle builders and attackers. One of the first upgrades was to swap wood for stone. This leads to the stone keep castle, with the bailey surrounded by a stone “curtain wall” which was hard to scale or knock down. Often the wooden keep was replaced with a square stone tower. Sometimes the palisade around the keep would be rebuilt in stone, giving a round keep known as a shell keep. Cardiff Cstle is an example. The stone wouldn’t burn and it made an imposing statement that those in the castle were here to stay permanently.

The stone keep would often then serve as a residence for the local lord. You can see the different levels, holes for timber frames and remains of fireplaces. There may have been a dormitory, kitchens, hall and even a chapel in some stone keeps.

Jonathon Davies, Going Postal
Inside the keep at Cardiff Castle. You can see the holes for timbers in the walls.
Jonathon Davies, Going Postal
Another view inside the keep. The remains of a chimney can clearly be seen.

So how do you adapt to this? Several methods wee developed. Catapults and trebuchets threw stones at the walls. They would target corners of the walls and towers as these were more vulnerable and tended to chip off. With enough direct hits a breach could be caused, or the tower might collapse.

Jonathon Davies, Going Postal
Reconstruction of a trebuchet at Warwick Castle.

Photo by Tyler Brenot on Flickr

Undermining also used a similar principle, but from underground. A tunnel would be dug under a corner which was supported by wooden props. Once under the required area, pig fat and oil was spread over the wood and set alight. It was then a race to get out before the tunnel collapsed. When it did it would hopefully collapse the wall or tower with it. Battering rams were an age old favourite. But stone walls were hard to penetrate. So they focused on attacking the gates instead, which were the weakest points in the curtain walls. Siege towers were also used, such as a belfry. These were essentially ladders encased in a wooden frame to protect the men inside. They were mounted on wheels and pushed up to the castle walls. Once there a ramp at the top of the tower was lowered over the top of the wall and the soldiers would storm out on to the ramparts and attempt to take the walls.

Round towers

To counter the threat castle builders started to use round or octagonal towers and keeps. While not necessarily a new idea they were found to deflect stones rather than absorb the impact head on. Ever wondered why tanks and armoured vehicles have armour at crazy angles? Similar principle. They also stood up better to undermining and archers had better fields of fire as they had no corners.

Jonathon Davies, Going Postal
Round towers on Bodiam Castle.

Native rulers such as the Welsh princes also built stone castles, such as Criccieth, Dinefwr and possibly Morgraig near Caerphilly. Generally they had smaller kingdoms with lower populations so could not raise as much through taxes. They were generally smaller and used D shaped towers (though not always).

Arrow loop windows

Clearly you wanted a way to shoot at the enemy while at the same time they couldn’t shoot at you. Large open windows were not a good idea with all those arrows and rocks flying around. One way to achieve this was arrow loop windows. It allowed you to see out and aim at attackers while those firing back at you had to hit a small target high up on a wall or tower.

Jonathon Davies, Going Postal
Arrow loop windows were hard to fire in to.


With battering rams attacking gates new ways had to be found to strengthen them. One way was a metal reinforced gate which could be lowered and raised at need known as a portcullis. Metal such as iron or steel is stronger than wood and absorbed the impact.

Jonathaon Davies, Going Postal
A portcullis reinforced the gate.


Crenellations on the top of castle walls provided a platform for soldiers to stand on, with alternating gaps to fire from and cover to hide behind. Attackers trying to reach the walls would be under fire in the open while soldiers atop the walls could shelter.

Jonathon Davies, Going Postal
Crenellations on the walls at Cardiff Castle.


Machicolations were platforms extending out over the walls with gaps in the floor. Through these defenders could fire arrows, drop stones or pour boiling oil, etc. All the while the defenders were protected.

Jonathon Davies, Going Postal
You can see the gaps through which the enemy could be attacked.


The barbican was a fortified gate house, often with towers. Some were so extensive they took on the look of a mini castle themselves. The gate would be housed inside. Often above were murder holes, where nasty things could be dropped on the attacker underneath in the same way as machicolations. In this way the weakest point of the castle wall was reinforced and became a daunting prospect to attack.

Jonathon Davies, Going Postal
A barbican gatehouse would be more difficult to attack.

This also helped defend against battering rams. The rams themselves were becoming ever more sophisticated, with wooden coverings to protect soldiers, and often covered with hides drenched in water to stop fire arrows.


Moats are water defences surrounding the castles. They have a number of uses. They stop defenders easily reaching the walls. They either have to swim or construct bridges, or pile up stones in the water to get across. Most moats have a narrow entrance and often a drawbridge. The narrow entrance means attackers have to focus their efforts here. It becomes easier to target them with arrows, and a small number of defenders can hold out against a much larger force. The drawbridge can be withdrawn to deny access. A moat also make undermining difficult. Tunnels dug towards the castle risk filling with water and drowning the attackers.

Caerphilly Castle has some of the largest water defences in Europe. You can clearly see the moat, narrow entrance, barbican and round towers. Caerphilly was built later than Cardiff Castle by the Norman, Gilbert De Clare. It was the main bulwark against the Welsh, in particular the Lord of Senghenydd, Llewellyn ap Grufydd who the Normans regularly fought with. Cardiff Castle then became more of an administrative centre for the De Clare family.

Concentric Castles

Concentric castles were the height of medieval castle technology. They contained many if not all of the features listed above. They had round towers, often gate houses, and consisted of two sets of walls. There was a lower outer wall and a higher inner wall. In this way it was possible for archers and siege weapons mounted on the wall to fire at the enemy at the same time if necessary. If the enemy made it in to the bailey area they would come under fire from the outer and inner walls. If the outer wall was taken, defenders could retreat to the inner wall and still fire down upon the enemy. Krak Des Chevaliers and Caerphilly are two examples of concentric castles. These castles were mainly developed in the 11th and 12th centuries. Edward I built a series of these castles across Wales to consolidate his power after making it a principality following several campaigns. An example is Beaumaris Castle.

By this time castles had become extremely difficult to attack. In some cases there are records of armies simply bypassing castles altogether rather than assault them. The main way to take them was by siege, trying to starve out the defenders. A cordon would be put all around the castles to stop anyone going in or out. If a castle was well provisioned a siege could take years. Often the besiegers were in a worse state than the defenders. During Henry V‘s siege of Harfleur in 1415, dysentery broke out among his men and he lost around a quarter of his troops to the disease. However, a new technological breakthrough was just around the corner.

The Coming of Cannons

Chinese scientists had invented gunpowder at some time in the 9th century. It had been slowly spreading westwards. By around the mid 1400s it was widespread, as were the cannons and muskets that used it. In 1453 cannons were used by the Ottomans to help capture Constantinople from the Christians, which is now called Istanbul. All the previous adaptation and defences were now rendered obsolete. Warfare itself was changing. Massed ranks of infantry with muskets were replacing archers. Archers  such as those carrying the English war bow (Longbow)  were much more accurate, but took a lifetime to train and were hard to replace. On the other hand any bloody fool could pull a trigger. What about accuracy? If 10,000 men were charging at you then you didn’t need to be accurate. Just fire in their general direction, you were bound to hit someone.

Jonathon Davies, Going Postal
Deal Castle in Kent was built by Henry VIII.

Castles had to change again to counter this threat. Tall curtain walls and towers were easy to hit. So walls became lower and thicker. Lower walls presented a smaller profile and so were harder to target. Thicker walls were needed to stand up to cannon balls. Platforms and emplacements for their own defensive cannons were built. Deal castle is a good example of this.

Star forts were used throughout Europe. Again they use a flatter profile. They were five or six sided to allow overlapping fields of fire, and eliminate spaces where the enemy could not be targeted. The angles and slope of the walls meant that shots that were not a direct hit were more likely to glance off.


As time moved on traditional castles had become redundant. Cannons could smash the walls. Warfare was changing, and also in places like the Britain the land was more peaceful and under settled rule. Castles because residences for the Royals and the nobles of the land, rather than military installations.

Castles changed again to reflect this. Arrow loop windows were replaced with much larger windows filled with glass. Additions were made in favour of comfort, towers and keep converted to living spaces. Castles would be remodelled to suit modern needs. Windsor Castle is an example. You can still see the original motte and bailey design, and there curtain walls and towers. But they now have large windows, with some near ground level. Many parts are later additions added over the years, for example by Charles II and later George III. It certainly wouldn’t be holding out against any sieges.

Fake Castles?

As was popular, castles like Windsor had many features added to them later. These were often done in the styles of a previous era to make them look “authentic.” Hence some of the square towers. This is also true of Cardiff Castle. The outer walls are actually a much more modern addition by the 3rd Marquess of Bute, who enlisted William Burges to restore and remodel the castle during the 1800s. The work was carried on by the 4th Marquess.

These modern features came in handy during WW2 when tunnels in the walls were used as air raid shelters. Others built large manor houses but called them castles, possibly for grandeur. Other castles were built as follies, using modern methods but to look medieval. Sometimes they were built on the foundations of an original castles. An example is Castell Coch on just outside of Cardiff. It has been used in numerous television productions.

Jonathon Davies, Going Postal
Castell Coch, near Tongwynlais.

This was another project by Burges for the Bute family. It was designed as a rural retreat. The castle was originally Norman but by the 18th century was in ruins. The 3rd Marquess, John Crichton-Stuart, was the richest man in the world at this point so had some cash to spare.

I have by no means given  an exhaustive list of castle features or methods of attacking a castle. Theses are the basics, and there are many more to learn about. To finish here is a castle in Romania, for no other reason than it looks cool.

© Jonathon Davies 2018

(Twitter photos attributed to those accounts. Photos with attribution from  and Flickr under the Creative Commons Attribution-Share Alike Licence Generic 2.0. and Flickr under the Attribution 2.0 Generic Licence. Other photos available through the Public Domain,  from or by Jonathon Davies.)


Audio file