Pierre d'Aubusson (1423 – 3 July 1503) was a Grand Master of the Order of Saint John of Jerusalem, and a zealous opponent of the Ottoman Empire.
In May 1480 a large Ottoman fleet appeared before Rhodes, carrying an invading army of some 100,000 men under the command of Mesih Pasha (originally a Greek by the name of Michael Palaiologos who had converted to Islam after the conquest of Constantinople by the Turks).
Rhodes not being considered secure, Cem with his own consent was sent to Bourganeuf in France where he was kept under the guard of Guy de Blanchefort, Pierre d'Aubusson's nephew.
D'Aubusson accepted an annuity of 45,000 ducats from Bayezid II, in return for which he undertook to guard Cem in such a way as to prevent him from appealing to the Christian powers to aid him against his brother.
[citation needed] The remaining years of his life d'Aubusson spent attempting to restore discipline and zeal in his Order and to organize a grand crusade against the Turks.
His last years were embittered by chagrin at his failure, which was hardly compensated by his success in extirpating Judaism in Rhodes, by expelling all adult Jews and forcibly baptizing their children.