The Ottoman Empire began in 1299 under Osman I and soon became the most powerful Islamic empire and one of the most powerful world empires in general. This rapid expansion was due in many cases to Islam, particularly under Mehmet the Conqueror and his grandson Selim I. Even later, under Abdulhamid II, Islam remained a major unifying force. Nevertheless, Islam could not stand up to nationalism, a force that would ultimately destroy the Ottoman Empire.

Mehmet the Conqueror

Mehmet the Conqueror ascended to the Ottoman throne in 1451, and in 1453 he conquered the Byzantine city of Constantinople, which Islamic empires had tried to conquer since the religion's founding in the seventh century. To emphasize the Islamic nature of his conquest, once of Mehmet's first acts was to reconsecrate the Hagia Sophia Cathedral as a mosque.

Selim I

Mehmet's grandson, Selim I, similarly used Islam to expand the borders of the Ottoman Empire. Selim's major achievement was the conquest in 1517 of the Mamluk Sultanate, which had ruled Egypt since 1250 and whose leaders claimed the title of caliph, or spiritual leader of all Muslims. After conquering the Mamluks, Selim adopted the title of caliph, which Ottoman sultans would hold until the 20th century and which once again emphasized Islam as central to their empire.

Abdulhamid II

During the 19th century, when the Ottoman Empire was waning in power, sultans beginning with Abdulhamid II began to reemphasize the Ottoman Empire's Islamic identity. Abdulhamid not only used more Islamic calligraphy on official buildings, but also began to gather and enshrine additional Islamic relics. This re-emphasis on Islam was designed to stanch the Empire's fragmentation, as its various Islamic populations began revolting against the sultan's power.

Nationalism

Nevertheless, despite later Ottoman sultans' attempts to reassert Islam as an identity, nationalism eventually became a more powerful force than religion. The Young Turks, a nationalist and secular movement within the Ottoman Empire, overthrew Sultan Abdulhamid II in 1908. And, of course, in 1914 during World War I the British fomented a revolution in the Ottoman Empire's Arabian provinces, led by Col. T.E. Lawrence. This movement would ultimately succeed defeating the Ottomans and destroying their empire at the end of World War I.