William II’s foreign policy (England of the Plantagenets)

In the second half of the 12th century, the Plantagenet court and the Palermo court were undoubtedly the most outstanding in the west. An "English" contingent was close to the king : Richard Palmer the bishop of Syracuse, was a friend of Thomas Becket. Peter of Blois, one of Henry's curiales (royal clerks), was ounce tutor of young king William of Sicily. London traded with Palermo and exchanges were notable in the province of the arts (court literature, enamel etc).
The relations between Henry II Plantagenet and William II of Sicily were in the framework of a complex diplomatic game acted out, at a European level, in the confrontation between the Pope and Emperor Frederick Barbarossa. In the 1170’s, Henry II Plantagenet, first of all a supporter of the emperor, was seeking alliances in his conflict with Thomas Becket. William II of Sicily, supported by the Pope, was an important interlocutor. Thus, Henry II Plantagenet preferred to abandon his alliance with Barbarossa and to draw closer to William and the Pope. But Becket’s murder in 1172 led to the failure of a first marriage project, which was finally realised in 1176. William married Joanna (11 years old), the daughter of Henry II of England, and Eleanor of Acquitaine in Palermo.
This prestigious marriage did not leave any heirs and was the end of the legitimate masculine lineage of the Hautevilles. During his passage in Sicily in 1190, Richard the Lionheart, using the pretext of financial engagements taken at his sister’s marriage, put pressure on the fragile government of Tancred of Lecce (1191-1194), the last Norman king of Sicily. 
Joanna accompanied her brother to the Holy Land. It was proposed that she would marry Saladin’s brother, but she married the count of Toulouse and died in Rouen in 1189.