Pontificate Borgia was elected pope at an advanced age as a "compromise candidate" in the conclave of 8 April 1455. He took the pontifical name Callixtus III. He was crowned on 20 April 1455 by Cardinal Protodeacon Prospero Colonna. After his coronation, he rode a white horse through the streets of the city and followed the ancient custom, known as Monte Giordano, where representatives of the Jews met with the pope and presented him with the roll of the law. Callixtus III then read from the law and stated "We ratify the law, but condemn your interpretation", which instigated a riot at the ceremony that endangered the pope's life. Not quite two years after the Fall of Constantinople in 1453, Callixtus was chiefly concerned with the organization of Christian Europe against an invasion by the Ottoman Empire. At the time, it was said that Callixtus III "speaks and thinks of nothing but the crusade", spending hours discussing the topic with a warlike zeal. An extensive building program underway in Rome was cancelled and the money funneled toward a crusade. Papal nuncios were dispatched to all the countries of Europe to beseech the princes to join once more in an effort to check the danger of a Turkish invasion. Missionaries were sent to England, France, Germany, Hungary, Portugal, and Aragon to preach the Crusade, and to engage the prayers of the faithful for the success of the enterprise. It was by order of Callixtus III that the bells were rung at midday to remind the faithful that they should pray for the welfare of the crusaders. The princes of Europe were slow in responding to the call of the pope, largely due to national rivalries. England and France's Hundred Years' War had just ended in 1453. Forces led by John Hunyadi (), Captain-General of Hungary, met the Turks and defeated them at Belgrade on 22 July 1456). Shortly after his victory, Hunyadi himself died of a fever. On 29 June 1456, Callixtus III ordered the church bells to be rung at noon (see noon bell) as a call to prayer for the welfare of those defending Belgrade. To commemorate this victory, Callixtus III ordered the Feast of the Transfiguration to be held annually on 6 August. In 1456 the pope issued the papal bull Inter Caetera (not to be confused with Inter Caetera of 1493), reaffirming the earlier bulls Dum Diversas