During the early part of the Norman invasion, the designers of these early castles built wooden towers on the top of a mound for protection. They either used an existing mound where one was available, enlarged an existing natural hill or more usually built their own mound on which they then constructed the tower or keep. At the top of the mound, around its edge, they built a wooden wall or palisade. The mound, now known as a motte, was usually surrounded by a ditch which in some cases could be filled with water. At the foot of the motte was built a normally oval-shaped enclosure known as a bailey that had a palisade and a ditch of its own. The motte was usually placed to one side of the bailey rather than in the centre. Some castles had more than one bailey. An example of this type can be seen at Windsor which has the motte at the centre of two large baileys.

The arrangment of the motte and baileys was dictated by the conditions of the ground on which they were built. Although many of these castles had the motte at the edge of the bailey, some had the motte within the baliey. An example of this is at Skenfrith Castle in Wales. Where there was more than one bailey, the baileys could be arranged in a line to one side of the motte, or, as at Windsor, opposite each other with the motte at the centre.

Two Mottes

Some motte and bailey castles had two mottes. Examples include Lincoln Castle and Lewes Castle.

Under Attack

When the area around a castle was under attack, the local inhabitants could retreat first to the bailey and then to the motte if the attackers managed to enter the castle. From the top of the motte the defenders could throw missiles at their attackers and defend or even destroy the narrow bridge that linked the bailey to the motte.