As they captured each territory, William and his men secured their
camps with simple earth and timber defenses characteristic of northern
Europe (Documents 2 and 3). These wooden structures have disintegrated,
but sometimes their earthen mounds survive as rolling hills or picturesque
elements in the landscape. Timber castles were especially useful
to a warrior king like William the Conqueror who moved rapidly to bring
new territories under control. The earth and timber castles could be built
quickly, since the newly moved earth did not have to support great
weight. Such structures were also relatively cheap because they required
no specialized masons and expensive stone. Since the timber building tradition
was widespread both in the British Isles and on the continent, the
carpenters knew the building techniques. These castles were essentially
towers and stockades; they provided garrison headquarters as well as residences.
William had learned the value, as well as the technique, of building
and using castles at home in Normandy, where castles and siege warfare
had been developed in the ninth and tenth centuries. The strong rule of
Charlemagne had given the people of Europe some sense of security, so
that Charlemagne’s grandson, Charles the Bald, even issued a prohibition
in 864 against the building of private fortifications. But intensified
Viking raids along the coast of France in the later years of the ninth century
forced the people to insist on permission to defend themselves and
to fortify their homes. By 869, Charles the Bald rescinded his edict, and
the landholders began building walls around their homesteads again. Relative
peace returned in 911 when the Viking chieftain Hrolf accepted
Christianity and became a vassal of King Charles the Simple. In return
Hrolf received the lands known today as Normandy, and as Rollo, duke
of Normandy, he and his Vikings became settlers and builders instead of
invaders and raiders.
Ninth-century castles were relatively small and simple affairs designed
to safeguard a relatively small number of people and intended as a refuge
during times of trouble. A timber tower on its hill or motte, natural or
artificial, could serve as a dwelling like the elaborate tower described by
Lambert of Ardre (Document 6). The hall and farm buildings stood near
the tower. A moat or ditch, earthen ramparts, and stockades surrounded
the site that formed the bailey. The owner built the tallest possible tower
and the highest walls; he depended on height for observation and defense.
Because he expected his enemies to try to enter in the same place
he did, he also fortified the gateway to the compound.