The site is likely to have been of strategic value, having a well, standing on high ground above the Somborne valley, and lying a short distance from the Roman road from Winchester to Sarum.
The castle was built during the Anarchy, a prolonged period of unrest and civil war between opposing factions led by King Stephen and the Empress Matilda.
Within fifty years, during the reign of Henry II's son King John, Ashley Castle was restored by a new owner, William Briwere the elder (c.1145-1226), probably in stone.
In an age when the crown saw a potential rebel stronghold in every castle held by a nobleman, and the Anarchy was a recent memory, permission to fortify in this way was a rare privilege.
[9] The manor of Ashley passed in 1312 from the Briweres to the Despensers,[3] a family in league with another unsuccessful and unpopular king, Edward II of England.
Hugh Despenser the Younger was an infamous favourite and counsellor of King Edward II of England, after whose overthrow in 1326 he was found guilty of high treason and hanged, drawn and quartered.
The ringwork was located on a spur of high ground and consisted of a banked rampart surrounded by a deep ditch, probably re-using the earlier Iron Age defences.
Extending westwards in a loop from the ringwork was a second, outer bank enclosing a broadly rectangular court - the bailey - which contained all the ancillary domestic buildings associated with such a settlement.
The castle is typically Norman in the small size of the occupied area and the strength of its ramparts, and in having a bailey; its north-east part contains visible remains of foundations.