Daubusson, Pierre (1423-1503), a famous French Grand-Master of the Order of St. John of Jerusalem. He entered the service of the Emperor Sigismund, and served under the Austrian Archduke Albrecht against the Turks. Returning to France, he served with distinction against the Swiss in 1444. He then joined the Knights of Rhodes, and became Grand-Master in 1476. He was a formidable enemy of Mahomet II., and his efforts to unite Christendom against the Turkish inroads gained for him the title of "Shield of the Church." In 1480 a force of 100,000 Turks invested Rhodes unsuccessfully for a month. The failure of this expedition aroused the wrath of Mahomet, who was meditating a greater attack when death came upon him in 1481.