Anglo-Norman language
The Norman Conquest led to a profound change in the history of the English state. William ordered the compilation of the Domesday Book, a survey of the entire population and their lands and property for tax purposes, which reveals that within 20 years of the conquest the English ruling class had been almost entirely dispossessed and replaced by Norman landholders, who monopolised all senior positions in the government and the Church. William and his nobles spoke and conducted court in Norman French, in both Normandy and England. The use of the Anglo-Norman language by the aristocracy endured for centuries and left an indelible mark in the development of modern English.