Turkey was a part of the Ottoman Empire, which for various political reasons entered WWI in November of 1914 on the German side of the War.  The Ottoman Empire had recently had some major setbacks in Europe and hoped to gain strength and concessions from Russia.  The war was a disaster and the final death knell for the Ottoman Empire.  One of the tactics the British used to defeat the Turks was to instigate an uprising among the Arab nationalists who desired freedom from Turkish rule.  The War ended with the British occupying the territory that would become present day Iraq, Palestine, Jordan, Lebanon, and Syria.  The Ottoman Empire was no more.  At the Paris Peace Conference, Britain and France made plans to divide up Turkey with the other former Ottoman territories but a new modernizing regime took control there and civil war ensued until control was siezed by Ataturk who wanted to reform Turkey as a Western nation introducing a somewhat republican system of government and westernizing Turkish culture.

Much of the information here comes from Jackson J. Spielvogel, Western Civilization, sixth ed. Thomson Wadsorth, 2006. p. 725 - 7, 747, and 757.