The nature of Anglo-Saxon land tenure was substantially changed by the Norman conquest of England in 1066, as all land was then held by the King under Norman feudal control. The King's tenants in chief held their land in return for provision of men at arms to the King. However, the changes in the nature of tenure were not absolute. Military service had been a duty of landholders before 1066 and some Anglo-Saxon law and custom continued to apply after the conquest. Domesday does not mention folkland or bookland, but the form of tenure in January 1066 (TRE) is frequently given. Although a variety of wording is used. Ann Williams equates land held "freely" (libere) with bookland.