Mehmed II made it clear at the meeting of his courtiers which decided and agreed to proceed with the conquest of Constantinople, that the Byzantine Empire had given refuge to claimants to the Ottoman throne, thus causing frequent civil wars. They also discussed that it was the Byzantine Empire which had been the main instigator of crusades. Constantinople, if surrendered to Western Catholics, as Salonica was, would mean that Ottoman Empire would never be fully integrated. The .siege of Constantinople lasted for fifty-four days, April 6--May 29, 1453

News had come of preparations by the Hungarians and leaving the ports by Venetian navy to help Byzantine Emperor XI Palaeologus. Mehmed II ordered his army to deliver a general assault. The enemy barricaded the Bay of Constantinople to block the penetration of the Ottoman fleet. Mehmed ordered transportation of his fleet to the other side of the city. His soldiers managed it through the desert, considered inaccessible so far, and reached the back gates of Constantinople. The Constantinople fell. The Greeks were allowed to return to Constantinople, who, after the conquest, paid ransom. They were granted immunity from taxation for a certain period. The day after the conquest, Chandarle, Grand Wazir of Constantinople, was dismissed and imprisoned. In his place his rival, Zaganuz, was appointed. The conquest of Constantinople turned Mehmed II overnight the most celebrated Sultan in the Muslim World. ۔