<P> The type of soil would make a difference to the design of the motte, as clay soils could support a steeper motte, whilst sandier soils meant that a motte would need a more gentle incline . Where available, layers of different sorts of earth, such as clay, gravel and chalk, would be used alternatively to build in strength to the design . Layers of turf could also be added to stabilise the motte as it was built up, or a core of stones placed as the heart of the structure to provide strength . Similar issues applied to the defensive ditches, where designers found that the wider the ditch was dug, the deeper and steeper the sides of the scarp could be, making it more defensive . Although militarily a motte was, as Norman Pounds describes it, "almost indestructible", they required frequent maintenance . Soil wash was a problem, particularly with steeper mounds, and mottes could be clad with wood or stone slabs to protect them . Over time, some mottes suffered from subsidence or damage from flooding, requiring repairs and stabilisation work . </P> <P> Although motte - and - bailey castles are the best known castle design, they were not always the most numerous in any given area . A popular alternative was the ringwork castle, involving a palisade being built on top of a raised earth rampart, protected by a ditch . The choice of motte and bailey or ringwork was partially driven by terrain, as mottes were typically built on low ground, and on deeper clay and alluvial soils . Another factor may have been speed, as ringworks were faster to build than mottes . Some ringwork castles were later converted into motte - and - bailey designs, by filling in the centre of the ringwork to produce a flat - topped motte . The reasons for why this decision was taken are unclear; motte - and - bailey castles may have been felt to be more prestigious, or easier to defend; another theory is that like the terpen in Netherlands, or Vorburg and Hauptburg in Lower Rhineland, raising the height of the castle was done to create a drier site . </P> <P> The motte - and - bailey castle is a particularly northern European phenomenon, most numerous in Normandy and Britain, but also seen in Denmark, Germany, Southern Italy and occasionally beyond . European castles first emerged in the 9th and 10th centuries, after the fall of the Carolingian Empire resulted in its territory being divided among individual lords and princes and local territories became threatened by the Magyars and the Norse . Against this background, various explanations have been put forward to explain the origins and spread of the motte - and - bailey design across northern Europe; there is often a tension among the academic community between explanations that stress military and social reasons for the rise of this design . One suggestion is that these castles were built particularly in order to protect against external attack--the Angevins, it is argued, began to build them to protect against the Viking raids, and the design spread to deal with the attacks along the Slav and Hungarian frontiers . Another argument is that, given the links between this style of castle and the Normans, who were of Viking descent, it was in fact originally a Viking design, transported to Normandy and Angers . The motte - and - bailey castle was certainly effective against assault, although as historian André Debord suggests, the historical and archaeological record of the military operation of motte - and - bailey castles remains relatively limited . </P> <P> An alternative approach focuses on the links between this form of castle and what can be termed a feudal mode of society . The spread of motte - and - bailey castles was usually closely tied to the creation of local fiefdoms and feudal landowners, and areas without this method of governance rarely built these castles . Yet another theory suggests that the design emerged as a result of the pressures of space on ringworks, and that the earliest motte - and - baileys were converted ringworks . Finally, there may be a link between the local geography and the building of motte - and - bailey castles, which are usually built on low - lying areas, in many cases subject to regular flooding . Regardless of the reasons behind the initial popularity of the motte - and - bailey design, however, there is widespread agreement that the castles were first widely adopted in Normandy and Angevin territory in the 10th and 11th centuries . </P>

Where was the first motte and bailey castle built