[3] At the age of four, shortly after the death of his older brother Roger, William had been crowned co-ruler by his father, Tancred, in Palermo.

Even before Tancred's death he had been laying plans to invade, and his resources had been further augmented by the ransom he had received for the release of King Richard I of England.

[8] Nevertheless, four days later, an alleged conspiracy against the new king was uncovered, and many of the leading Italo-Norman political figures were arrested and sent to prison in Germany, including William and his family.

Henry's son, Emperor Frederick II (who was also king of Sicily) discovered Tancredi Palamara in Messina and had him executed in 1232.

William's heir was his younger sister, whose precise name is unclear but has been given variously as Mary, Elvira, Albinia or Blanche.