After the taking of Constantinople by the Turks (1453), Pius II founded the Order of Our Lady of Bethlehem. The purpose of these knights was to defend the Island of Lemnos which Cardinal Louis, Patriarch of Aquileia, had recaptured from Mohammed II. The island was to be their headquarters from which they were to oppose the attacks of the Muslims by way of the Ægean Sea and the Hellespont. The order was composed of brother-knights and priests governed by an elective grand-master. The white costume worn by the members was decorated with a red cross and the rule prescribed for them was very similar to that of the Knights of St. John of Jerusalem. The pope installed this community on 18 January 1459. To supply their needs, the pope turned over to them the property and revenues of the orders of St. Lazarus, Sainte-Marie du Ch teau des Bretons, Bologna, of the Holy Sepulchre, Santo Spirito in Sassia, St. Mary of the Crossed Friars, and St. James of Lucca, all of which were suppressed for this purpose. Pius II alluded in a Bull to this foundation and the bravery of its knights, but the second capture of Lemnos by the Turks rendered the institution useless. Thus the order of Our Lady of Bethlehem was suppressed almost as soon as founded and those orders whose goods the pope had transmitted to it were re-established.
This article incorporates text from a publication now in the public domain: Herbermann, Charles, ed (1913). Catholic Encyclopedia. Robert Appleton Company.