Legend has it that the first fortification of significance on the grounds of Warwick Castle was erected by Ethelfleda, the daughter of Alfred the Great, in the year 914. This almost certainly replaced older wooden fortifications which had proven ineffective against marauding Danes who sacked the town during the reign of her father. This fortification was part of a network built to protect the Kingdom of Wessex.
The remains of this ancient fortification can still be seen on Ethelfleda's Mound, a mound of earth at the southern end of the castle's courtyard. As intriguing as this legend is, the majority of the remains date from the period of Norman rule.
After the Norman Conquest of England in the 11th century, William the Conqueror appointed Henry de Newburgh as Earl of Warwick. During this time of change, a Norman motte-and-bailey fort was erected.
In the year 1264, the castle was built by the forces of Simon de Montfort, who consequently imprisoned the Earl of Warwick at that time, William Mauduit, and his countess at Kenilworth (who were supporters of the king and loyal’s to the barons) until a ransom was paid.
After the death of William Mauduit, the title and castle were passed to William de Beauchamp. Following the death of William de Beauchamp, Warwick Castle subsequently passed through seven generations of the Beauchamp family, who over the next 180 years were responsible for the majority of the additions made to Warwick Castle.
After the death of the last direct-line Beauchamp, Anne, the title of Earl of Warwick, as well as the castle, passed to Richard Neville ("the Kingmaker"), who married the sister of the last Earl (Warwick was unusual in that the earldom could be inherited through the female line). Warwick Castle then passed from Neville to his son-in-law (and brother of Edward IV of England), George Plantagenet, and shortly before the Duke's death, to his son, Edward.