The War of Cyprus became the focus of Spain’s attention after Pope Pius V sent an envoy to urge Philip to join with him and Venice in a Holy League against the Turks. Philip II agreed and negotiations opened in Rome. Among Philip's terms was the appointment of John as commander-in-chief of the Holy League armada. While he agreed that Cyprus should be relieved, he was also concerned to recover control of Tunis, where Turks had overthrown the regime of Philip's client Muslim ruler. Tunis posed an immediate threat to Sicily, one of Philip II's kingdoms. Philip II also had in mind the eventual conquest of Algiers, whose corsairs posed a constant nuisance to Spain. Charles V had tried, and failed, to take it in the course of the Algiers expedition (1541).