In 1055 a group of Central Asiatic Turks, the SELJUKS, conquered Baghdad and established a Middle Eastern and Anatolian empire. When this empire was broken up by the Mongol invasion, one of the remaining local powers became known as the Ottoman dynasty, after its leader OSMAN I. The OTTOMAN EMPIRE spread from northwestern Anatolia and captured Constantinople in 1453. At the peak of their power the Ottomans controlled much of the eastern Mediterranean. The Ottomans had a sophisticated system of internal administration and also organized the first standing army in Europe.
As the Ottoman Empire began to collapse under its own weight in the 18th and 19th centuries, it became a battleground for rival European powers, wedged as it was between the Russian and Austrian empires (see EASTERN QUESTION). By the outbreak of World War I the Ottoman Empire had essentially been divided into spheres of influence by the great European powers, but a reform movement was active within the Ottoman Empire itself. The YOUNG TURKS brought about a revolution in 1908 and were successful in introducing civil and social reforms of far-reaching consequence.
In 1922, however, the Turks, led by Mustafa Kemal (later known as Kemal ATATURK) and Ismet INONU, defeated the armies occupying Anatolia. Inonu then won what has been called "the greatest diplomatic victory in history" when the Treaty of Lausanne (see LAUSANNE, TREATY OF) recognized the Republic of Turkey. The republic was declared on Oct. 29, 1923, and Ataturk was elected its first president. Turkey remained neutral in World War II until it joined the Allies in February 1945. Turkey joined the North Atlantic Treaty Organization (NATO) in 1952.