We hold the ideas and introduction of medieval castles to the Norman invaders. We had some strong establishments before that introduction, but very few. Violet le Duc has said that the first people in Western Europe to build castles were the Normans, but not as isolated fortresses, but as a way of general defense. This political idea of building such castles affected the locations and distribution of castles throughout the country.

Castles would be built in almost every major town and the river vallets, main traffic ways, fords and bridges ended up being guarded by the individual castles. In particular the south-east, the part which ended up being most susceptible to invasion would be the coast, but all convenient landing places were protected. Other castles would keep the main communication lines open throughout the country, whilst in the dangerous areas; each large estate would have a castle built primarily for the tenant, but also as a general defense for the neighborhood. These types of castle were in numbers on the Scottish border and in the Welsh Marches.

There is a widely spread opinion on classifying Medieval Castles. The most common one would be based on the defense system each castle had adopted. According to this classification, the presence or absence of such defense mechanisms would be the distinguishing decider. This would divide the castles into two main types:

• Castles with keeps.
• Keep-less castles.

Castles with keeps may be:
Castles with rectangular keeps.
Castles with shell keeps.
Castles with circular keeps.

The first two groups are normally associated with the castles typical of the Norman period. The third type originated in Norman times but lasted til the days of the Edwards. They may be considered as belonging to the reigns of Richard and John and to the earlier part of Henry VIII’s reign. That would be, to the earlier part of the period, known architecturally as Early English.

Keep-less Castles can also be sub-divided into three categories:

Castles of Enceinte: where the keep was discarded and a main ward taking its place, surrounded by a lofty wall of fortification, flanked by bold mural towers in cylindrical form, containing the state and domestic apartments. These castles primarily belonged to the latter years of the reign of Henry VIII and to his successor.

The Edwardian or Concentric Castles: the main ward would be surrounded by another line of defence, possibly a third also; subordianted and commanded by the inner ward.

The later castles had decided that the idea of defense was basically similar to that of domestic comfort. They were usually quadrangular in plan, built around an inner courtyard, with towers, pretty much rectangular at the corners, and with ahuge gate house at the middle of one side of the castle. This type of castle began to be built during the reign of Richard II, and became the most common in the 15th Century.

Overall, we might say that after starting with the Norman Castle, the subsequent development of the English Medieval Castles was governed by three factors

Altogether, starting with the Norman built castles, the development of English castles succeeding were governed by three main factors:
• The evolution of luxury and the ever increasing idea of comfort.
• The slow, but gradual improvement of methods of attack.
• The introduction of more scientific military architecture from the Byzantine Empire.
The first factor led to the disposal of the keep as a place of residence: it would always be cold, inconvenient and uncomfortable. The cramped accomodation became too much for the growing number of dependants in personal service.

The improvement in the art of seige craft was of at least equal importanct in the developments of the castles. All throughout the medieval period, the art of defense was always more important than the art of attack. Even the gunpowder did not alter the relation.

Throughout the crusades, the soldiers of Western Europe had become acquainted with the art of fortification of the Byzantine Empire. This was introduced before Edward I’s reign. The main ward was girt with a high wall, strengthened by a projection of mural towers encircling it. This was placed
so that the opposing attackers could approach the bottom of the wall without being exposed to an overwhelming strike from them. All wards were completely dominated by the high wall of the inner ward that even if taken, they couldnt be held against it.

A dramatic change took place during Edward III’s long reign in the development of castles. Fortress type castles ceased being a necessity and a few new ones built on the Scottish border. A single defensible castle was founded in Edward’s reign. Many of the existing royal castles fell into disrepair or could be handed over to be used as jails in their counties.

The place of fortress-type castles were superceded by castle-palaces of the last group. Quadrangular groups of buildings were built surrounding a central courtyard, adorned by attractive physical features rather than protected by angle towers, gate-house and moat. Leeds Castle is an epitome of this type of castle. An attempt at defensibility was made by the thickness of the outer walls and the absence of any external openings, but the majority of the castles had large external windows and walls of no major strength.