Motte and bailey

A motte-and-bailey castle is a fortification with a wooden or stone keep situated on a raised earthwork called a motte, accompanied by an enclosed courtyard, or bailey, surrounded by a protective ditch and palisade. Relatively easy to build with unskilled, often forced, labour, but still militarily formidable, these castles were built across northern Europe from the 10th century onwards, spreading from Normandy and Anjou in France, into the Holy Roman Empire in the 11th century. The Normans introduced the design into England and Wales following their invasion in 1066. Motte-and-bailey castles were adopted in Scotland, Ireland, the Low Countries and Denmark in the 12th and 13th centuries. By the end of the 13th century, the design was largely superseded by alternative forms of fortification, but the earthworks remain a prominent feature in many countries.

A motte-and-bailey castle was made up of two structures, a motte, a type of mound–often artificial–topped with a wooden or stone structure known as a keep; and at least one bailey, a fortified enclosure built next to the motte. The term "motte and bailey" is a relatively modern one, and is not medieval in origin. The word "motte" is the French version of the Latin mota, and in France the word motte was initially an early word for a turf; it then became used to refer to a turf bank, and by the 12th century was used to refer to the castle design itself. The word "bailey" comes from the Norman-French baille, or basse-cour, referring to a low yard. In medieval sources, the Latin term castellum was used to describe the bailey complex within these castles.

One contemporary account of these structures comes from Jean de Colmieu around 1130, describing the Calais region in northern France. De Colmieu described how the nobles would build "a mound of earth as high as they can and dig a ditch about it as wide and deep as possible. The space on top of the mound is enclosed by a palisade of very strong hewn logs, strengthened at intervals by as many towers as their means can provide. Inside the enclosure is a citadel, or keep, which commands the whole circuit of the defences. The entrance to the fortress is by means of a bridge, which, rising from the outer side of the moat and supported on posts as it ascends, reaches to the top of the mound." At Durham Castle, contemporaries described how the motte-and-bailey superstructure arose from the "tumulus of rising earth" with a keep rising "into thin air, strong within and without" with a "stalwart house...glittering with beauty in every part".

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