The English conquest of the district now known as Wiltshire began in 552 AD with the victory of Saxon Cynric over the native Britons at Old Sarum, by which the way was opened to Salisbury Plain.
By the 9th century the district had acquired a definite administrative and territorial organisation, Walstan, ealdorman of the Wilsaetan, being mentioned as early as 800 as repelling an attempted invasion by the Mercians.