When William defeated Harold at the Battle of Hastings in 1066 he was ready and prepared to stamp his authority on England. There were few castles in England so William had cleverly brought with him the frameworks for several wooden castles which were quickly erected in key strategic locations, including those sites close to Anglo-Saxon towns. The castles housed Norman knights and lords who were loyal to the king, and in turn these knights and lords swore to provide soldiers for the king in times of need.
Initially approximately 75% of the timber castles were of motte (an earthen mound) and bailey (a ditched enclosure) construction. Some castles could be built on existing hills or man-made mounds but in the main a motte had to be constructed by hand, layering clay, soil and sand until the appropriate elevation was achieved.
A timber tower (keep) would normally be sited on the motte to provide a clear view of the surrounding area and provide additional protection. Also, within the bailey there would be buildings to house the hall, kitchens, a chapel, barracks, stores, stables, forges, workshops and facilities required for the day to day running of the castle. To further strengthen the castle’s defenses the bailey could be surrounded by a palisade wall made from wooden stakes or tree trunks. The main weakness to these early castles was the vulnerability of timber to fire.
Gradually the wood structures were replaced with stone as the thick, strong walls offered much better defense. There are two basic shapes of a keep, square and round usually with kitchens on the ground floor, living quarters on the top floors and an entrance by stone steps to the first floor. For further protection the keep would be surrounded by a thick stone wall, some of which had turrets for lookouts. There would also be a drawbridge over a moat or ditch which could be raised to keep unwanted visitors out.
Although some were rectangular, the square keep was the easiest and fastest to erect and the most popular construction for the earlier keeps. Unfortunately the square keep had a major drawback, the weak point was its corners which could be easily damaged enabling invaders to breach the walls. Probably the most famous square keep is that of the White Tower or Tower of London, ordered to be built by William in 1078.
One of the strongest castle designs was the round keep. The tower was a better defensive construction than that of the square keep as there were no corners that would prevent the view of the archers firing on the enemy, and incoming arrows and rocks tended to glance off the rounded walls.
Often described as a Castle within a Castle, it comprised of two or more concentric walls built of thick stone. The outer wall would have towers facing all directions and a gatehouse. Behind this wall would be the outer bailey sometimes known as the ‘death hole’ because those invaders caught within this area were at the mercy of the archers shooting from the inner wall. There was an inner bailey behind the inner wall. The inner wall was higher than any of the outer walls with the strongest having round turrets positioned at intervals and one or more gatehouses. Because the inner wall was the higher, the archers could fire at invaders and over the heads of the archers on the outer walls. In medieval times concentric castles were often thought to be unbeatable, the only hope of victory to lay siege and starve the castle to surrender. However, most castles had their own water supply and were able to grow their own food.