Castles as we know them today are a far cry from the buildings of the early medieval era. Lost in history are the exact origins of these fortresses but we can surmise that they began as simple barriers set up as protection for the warriors of the day. Simple berms made from dirt and stone were set up and used as defense positions by soldiers and knights. These berms were eventually fortified with strong timber walls or palisades similar to the forts we see in the old western movies. However, late in the 9th century Nordic raiders, the Vikings began invading central Europe, specifically the area that is now France. The French at the time were not very organized and the raiders caused a great deal of havoc among the inhabitants, especially the nobles and these fortifications were no longer sufficient for protection. A defense method was needed to protect the interests of the population. The solution was to build castels (castles). These early castle were called Motte and Bailey castles.
Motte and Bailey is a Norman French term the means mound and enclosed land. The palisades were enlarged, a mound or motte was built within the palisade and a building or Keep was built on the flat top of the mound. Timber was readily available and was employed as the main construction material. An additional timber wall was sometimes built around the keep for further protection. Other buildings were included in the outer grounds or bailey. As a further method of defense a large ditch, or fosse, was dug around the bailey and was often filled with water.
On the European Continent the Motte and Bailey style of castles were effective against the attacks of the Vikings who had previously employed a method of attack based on the element of surprise. Come in, raid a village and quickly leave the area before the victim villages could raise a defense. It was easy for the invaders to terrorize helpless and mostly unarmed villagers when there was no real defense available. That would change soon enough as the innovation of castles took hold in Europe proper.
By the eleventh century the Vikings had occupied the area in Northern France known as Normandy, these folks adopted the French language as well as their method of defense. They became the Normans. In 1066, under William the Conqueror, the Normans invaded England and defeated the English King Harold II at the Battle of Hastings. The Norman forces established themselves in England by building many such timber castles, which could be put up quickly in a few days, or weeks for larger castles. It was at this time that the Britons started to use castles as a way of defending themselves against attack.
Windsor Castle in Berkshire was in fact originally a Motte and Bailey Castle. Motte and Bailey castles were advantageous due to the inexpensiveness and availability of materials and the rapidity of construction. They were also disadvantageous because they caught fire easily and were not all that strong against a concentrated attack.
The evolution of castle building went from the wood and dirt structures to stone in around 1100 A. D. Concentric Castles appeared in the 12th century. Concentric means one circle inside another. This type of construction though similar to the Motte and Bailey design was more secure against attack because instead of one wall or palisade the newer configuration often included a second inner and sometimes a third wall, with each wall built higher than the one surrounding it, thus allowing the defenders to see and shoot their arrows over the outer walls. The castle keep was built within the inner wall, though not all castles had a formal keep, some were simply a series of towers connected by walls that could be up to thirty feet thick. Less important buildings were placed between the two walls and the vital structures were within the inner circle. Moats and drawbridges were still used as added defense mechanisms in concentric stone castles.
The space between the walls was commonly known at the death hole. This was because an attacker caught between these walls would almost certainly face death. Concentric castles built of stone became increasingly more popular with the advent of gunpowder sometime in the 13th century. The stronger structures were able to withstand a siege whereas the old wooden ones obviously could not.
As time passed, improvements were made; slit windows for archers, ramparts, steep banks of earth or rubble were added outside of the walls forcing attackers to climb over an additional obstacle. Heavy iron gates closed off entrances, drawbridges were strengthened, and towers were built that protruded out from the walls giving the forces inside a better view of the immediate surroundings thus eliminating blind spots at the corners. Eventually cannons were installed on the upper walls.
After conquering England the Normans used castles as a way of preventing counter attacks by the British forces. Hundreds of motte and bailey castles were built throughout England for this purpose. Any town or village where rebellion was a suspected possibility had a castle built for defense, especially along the border with Wales, and, note this, along the northern border with Scotland.
Originally these castles were under the direct control of King William, but as time went by William allowed his loyal and trustworthy followers to build their own castles, as well. In the twenty years that William occupied England more than 500 castles were constructed across the land. After the Normans had become well established many of the timber castles were reconstructed using stone.
The stone castle required a different type of building site than the timber. Stone was not as readily available as wood and the construction site had to be much more stable in order to support the massive weight. Many were by necessity built on level ground but the strength of the walls allowed for higher towers so the results were to provide a view of the surrounding area. If the timber castle was built on an existing high spot such as a natural hill or cliff edge then the existing site could be used.
Castle building continued after the death of King William (in a riding accident). The square stone tower had been developed toward the end of the 11th century. Our own Fatlips Castle is an example of this style of castle. Castles were built through the 12th century becoming stronger and larger as building skills were refined. Round or curved walls and towers were built to eliminate corners which were potential blind spots to the defenders. Concentric castles were the predominate style built. New innovations were incorporated in the construction of castles. Traps were added within the walls to contain invaders that happened to breach the walls. A gate would close behinds the invaders and the defenders could rain arrows and other missiles down in the entrapped fighters. Boiling liquid could be poured down thought slots in the walls called murder holes.
Eventually though weapons were developed that could defeat a castles protection, the foremost of these was, of course, gunpowder. With portable cannons, an invading force could breach the outer walls and demolish gates. While the castle remained a valuable place for garrisoning troops and safe housing for the nobility, they no longer were an ultimate safety net for long sieges. As the feudal system of city states and internal battling for land evolved into consolidated nations in Europe the need for castles diminished and they ceased being built.
Though many castles remain today throughout Europe none are truly military establishments. By the 16th century the nobility wanted more comfort that that afforded by cold hard stone castles. Opulent palaces and county estates took the place of castles as home for the wealthy class. Many of the important castles have fallen into ruin or are in danger of doing so. Some in Scotland have been preserved as historic sites while others were completely dismantled and the stones used for other new projects.