The Use of Castles
The building of the White Tower, the donjon in the Tower of London, about 1080. The castle was placed in the south east corner of the old Roman city wall, the other sides protected by ditch and palisades.
One of the major weapons in William’s armoury was his abundant use of castles. A castle was a fortification and a home for a lord, be he noble or king. England was dotted with burhs, large fortifications which might surround a town, often of earth and timber, but these were communal defences, not private dwellings. Edward the Confessor had introduced castles with his Norman favourites, but these were few in number.
Whenever William came to a place of sufficient importance, he planted a castle. Often this was in a town, and might necessitate pulling down a number of houses once the Norman engineers had selected the best site. Most of the castles of the day were of earth and timber. This meant that they could be erected in a matter of weeks or months, a useful attribute in a hostile land. English labour was employed, probably utilising the king’s right to burh work.
The simplest form was the defended enclosure, now called a ‘ringwork’. The area to be defended was surrounded by a ditch, the earth from which was placed on the inner edge to form a bank. This was then topped with a stout palisade of upright wooden posts. Inside were all the buildings necessary for a self-sufficient unit, including a hall, kitchen, stables, storehouses, workshops, and a well. Some castles additionally had a mound of earth at one side, the ‘motte’, which carried a palisade on the flattened summit and a building within it. The latter could be used as a hall on larger examples, or else as a watchtower and last-ditch defence. Such ‘motte and bailey’ castles are shown on the Bayeux Tapestry at Dinan, Dol, Rennes and Bayeux, though not all sites have evidence for such. At Hastings the motte, with rammed earth layers, is shown under construction. Again, the surviving motte does not show this type of construction, though the original remains of the motte may be inside.
The Tapestry shows William in council at his palace at Rouen. Here was a large stone tower or donjon (now destroyed) which may have been the inspiration for the surviving donjon at the Tower of London. At this time such ‘keeps’ were never numerous in Normandy or England, as they were expensive and slow to build. However, being of stone they were resistant to fire, though many may have been used as symbols of power, and for ceremonial or social functions, far more than defence. Stone was gradually used more and more, to replace the palisades on the motte (producing the so-called ‘shell keep’) and the bailey defences. The castle had come to stay.
Norman Stone Castles (1), The British Isles 1066-1216 (Fortress 13),
Norman Stone Castles (2) Europe 950-1204 (Fortress 18), Osprey Publishing