The Romans first put their feet under the table here, but Winchester really took off when the powerful West Saxon bishops moved their Episcopal see here in AD 670. Thereafter, Winchester was the most important town in the powerful kingdom of Wessex. King Alfred the Great (r 871–99) made it his capital, and it remained so under Knut (r 1016–35) and the Danish kings. After the Norman invasion of 1066, William the Conqueror arrived here to claim the throne of England, and in 1086 he commissioned local monks to write the all-important Domesday Book, an administrative survey of the entire country and the most important clerical accomplishment of the Middle Ages. Winchester thrived right until the 12th century, when a fire gutted most of the city, after which London took its crown. A long slump lasted until the 18th century, when the town revived as a market town.