William I of Cagliari
William I (c. 1160–1214), royal name Salusio IV, was the judike of Cagliari, meaning "King", from 1188 to his death.
A member in the medieval Sardinian "Judges", he consolidated his power through both military force and political intrigue.
The Pisans mercilessly assaulted Genoese merchants in Cagliari and despoiled their landed possessions, evicting them from the giudicato.
The period of silence may be explained by William's accompaniment on the Third Crusade with Ubaldo, Archbishop of Pisa, a pilgrimage which is referenced in a papal letter of early 1200.
On 7 July 1188, the emissaries (cardinals) of Pope Clement III declared a general peace to be observed on the island.
A treaty was signed whereby Prunisinda was to be released and Constantine was reserved the right to pay for the return of Goceano or any castle of equal value.
William advanced on Oristano, Arborea's chief port city, and demanded the cession of several frontier castles, including Marmilla, which he obtained.
William then captured Peter and his son Barison and imprisoned them in order to control Arborea more directly.
On 11 August 1198, Pope Innocent asked the Archbishop of Cagliari, Bishop of Sorres, and the Pisan Bandino, Archbishop-Elect of Torres, to investigate the foundation of the accusations against Giusto.
Giusto claimed that Arborea was a fief of the Holy See and that the canons of Oristano had no power to grant the judgeship to William, who had ousted Peter and imprisoned him.
Unbeknownst to the pope, he had made a secret pact with Hugh whereby he retained control not only of Peter's half of Arborea, but also of all the fortresses in the realm.
The prospect of interference from William of Cagliari, Comita of Logudoro, and Hugh and Peter of Arborea was great.
When William Malaspina, son of Moroello and brother of his wife Adalasia, entered Gallura with the intent of abducting and marrying the minor Elena, William removed him, much to the praise of the pope, who claimed the right to choose her husband according to the late Barison's will.
Nonetheless, a papal letter of 15 September 1203 mentions that William had accorded Malaspina the administration of Gallura and protection of Elena's rights.
In 1206, William turned his sights on obtaining Gallura by force, but the giudicessa Elena married Lamberto Visconti, who rebuffed his assaults (1207).
In 1213, despite that lack of a formal oath, Innocent considered William to hold his lands in fief from the Holy See.
Around 1207, he married his second wife Guisiana,[8] daughter of a Tuscan count at odds with Pisa, Guido Guerra III.
However, even in Pisa he signed a document as Salusio IV de Lacon[9] when granting immunities to San Vito, a Sardinian dependency, on 10 May 1211.
He assumed control of Massa, which thitherto been in the hands of relatives, and forced Pisa to accept four rectors, one of which was a Visconti.
