It had in fact been long since Europe had been sufficiently united to oppose with any vigor the oncoming Turks. The Popes of Rome had been the most persistent foes of Turkish advance in Europe; notably Calixtus III, who in 1453 tried in vain to save Europe from Mohammed’s conquering armies; Pius II, who having for his master—thought the freeing of Europe from Islam, preached a general crusade, and even attempted to convert Mohammed by letter; Paul II, who gave lavish aid to Scanderbeg and the armies in Hungary and Albania in their struggle against Turkish invasion; Alexander VI, who held Prince Jem, the mutinous brother of Sultan Bayazid, as hostage for the friendliness of the sultan whom he attacked after Jem’s death; and Julius II, who planned a crusade early in the sixteenth century, but failed to execute it.[95] All this time Turkish conquest continued practically unhindered. By the close of the fifteenth century the Turks were accepted as a permanent political factor in Europe. Nevertheless, when Charles became a candidate for election to the headship of the Holy Roman Empire, he emphasized his fitness for the high office by alleging that his vast possessions, united to the Imperial dignity, would enable him to oppose the Turks successfully.[96] But the sudden rise of revolt within the Church tended to force the dread of Islam into the background, even in the face of the loss of Belgrad and Rhodes. At least such was the case with Charles V and the German princes; it was of necessity otherwise with little King Lewis, who saw with terror the preparations of the Turkish conquerors for war to the death with Hungary. As Suleiman’s conquests naturally threw him into antagonism with Austria, equally naturally he had common interests with Francis I. Friendly relations between the Porte and France were not unprecedented, although strongly disapproved by the more religious among the French. Commercial agreements had existed for some time between the two states.[97] The accession of Francis I, January 1, 1515, marked an epoch in the Eastern Question. Francis’ Oriental policy began on the conventional lines; he made an agreement with Leo X to drive the Turks from Europe but refused to subsidize Hungary in the interests of this purpose. The pope called for a truce in Europe and a crusade against the common enemy, but the death of Maximilian and the outbreak of the Protestant Revolt put a complete stop to this plan. The only result was the extension of the circle of European politics to include Eastern affairs and the Ottoman Empire, and to bring the Eastern Question home to all the European powers. Those who had been furthest away were now drawn in; France, Spain, and even England began to step within the circle of Eastern influence.