Built in 1069 by William the Conquerors son in law, the castle replaced an earlier timber castle on the same site. It is one of only two Motte and Bailey castles in England that have a double Motte within the bailey.The Castle and town were the scene of a great battle during the second Barons Rebellion in 1264 when forces of Baron De Montofrd successfully routed King Henry III leaving much of the town as a burning ruin. The King was captured in the Battle of Lewes but later freed when his son Edward ( later Edward I, Edward Longshanks, the Hammer of the Scots ) defeated the rebels once and for all in the Battle of Evesham. By the time of the English Civil war the castle was disused and dilapidated being quarried as a source of building material for the town. Today the castle is owned and run by Sussex Archaeological Society.