In 1446, the parliament elected him governor (1446–1453), then regent (1453–1456). He was a successful crusader against the Ottoman Turks, one of his greatest victories the Siege of Belgrade in 1456. Hunyadi defended the city against the onslaught of the Ottoman Sultan Mehmed II. During the siege, Pope Callixtus III ordered the bells of every European church to be rung every day at noon as a call for believers to pray for the defenders of the city. However, in many countries (such as England and the Spanish kingdoms), the news of the victory arrived before the order, and the ringing of the church bells at noon was transformed into a commemoration of the victory. The Popes did not withdraw the order, and Catholic (and the older Protestant) churches still ring the noon bell in the Christian world to this day.