During the rule of the Palaiologan emperors, beginning with Michael VIII in 1261, the economy of the once-mighty Byzantine state was crippled, and never regained its former stature. In 1369, Emperor John V unsuccessfully sought financial help from the West to confront the growing Turkish threat, but was arrested as an insolvent debtor in Venice. Four years later, he was forced-like the Serbian princes and the ruler of Bulgaria-to become a vassal of the mighty Turks. As a vassal state, Byzantium paid tribute to the sultan and provided him with military support. Under John's successors, the empire gained sporadic relief from Ottoman oppression, but the rise of Murad II as sultan in 1421 marked the end of the final respite. Murad revoked all privileges given to the Byzantines and laid siege to Constantinople; his successor, Mehmed II, completed this process when he launched the final attack on the city. On May 29, 1453, after an Ottoman army stormed Constantinople, Mehmed triumphantly entered the Hagia Sophia, which would become the city's leading mosque. Emperor Constantine XI died in battle that day, and the decline and fall of the Byzantine Empire was complete.
In the centuries leading up to the final Ottoman conquest in 1453, the culture of the Byzantine Empire-including literature, art and theology-flourished once again, even as the empire itself faltered. Byzantine culture would exert a great influence on the Western intellectual tradition, as scholars of the Italian Renaissance sought help from Byzantine scholars in translating Greek pagan and Christian writings. (This process would continue after 1453, when many of these scholars fled to Italy from Constantinople.) Long after its "end," Byzantine culture and civilization continued to exercise an influence on countries that practiced its Orthodox religion, including Russia, Romania, Bulgaria, Serbia and Greece, among others