Some general questions about the period of castle warfare in britain. When were manorial estates replaced by castles and how long did barons usually spend building their castles? How many men were employed building them? Were castles ever attacked during construction?
While castles arrive en masse in England with the Norman Conquest of 1066, there had been some earlier castles, mostly in the Welsh Marches built by Norman mercenaries in the employ of Edward the Confessor. The earliest castles are typically wooden motte-and-bailey types that are relatively quick to build, but these are soon supplanted by more substantial stone buildings.
Castles mark a change in the form and function of manorial estates in England; prior to the conquest, Anglo-Saxon nobles often oversaw the provinces under their responsibility from within their own estates. Towns, burhs and other settlements, while theoretically under the auspices of an ealdorman, were more practically administered by a thegn or, more likely, a hundredman, and in the case of a royal vil or burh, potentially a reeve. Post-Conquest, the castle increasingly became the site of these manorial functions whilst simultaneously serving as a fortified refuge from a potentially hostile population. While rural and isolated castles serving a manorial function certainly did exist, they increasingly also became associated with larger settlements.
In an urban context, castles allowed a Norman elite to actively oversee the administration of the major population centres likely in a far more immediate way than their English predecessors, while also serving as an omnipresent reminder to the local population of the Normans' grasp power and their strength. In cities like Exeter, Bristol and Stafford, castles served as both external and internal defence, as well as manorial centres. It's worth noting that many castles were built in the immediate wake of a military campaign, likely while Norman forces were still in local operation. Exeter's Rougemont castle, for example, was built in 1068 immediately following the siege of the city by William I against a rebellion led by the mother of Harold I. While the city agreed to surrender peacefully in return for the assurance of the previous rights and privileges of its populace, the castle was erected immediately within the city's walls to discourage further acts of rebellion.
What kinds of structure did people live in before there were castles?