On May 16, 1916, representatives of Great Britain and France secretly reach an accord, known as the Sykes-Picot Agreement, by which most of the Arab lands under the rule of the Ottoman Empire are to be divided into British and French spheres of influence with the conclusion of World War I.
After the war broke out in the summer of 1914, the Allies—Britain, France and Russia—held many discussions regarding the future of the Ottoman Empire, now fighting on the side of Germany and the Central Powers, and its vast expanse of territory in the Middle East, Arabia and southern-central Europe. In March 1915, Britain signed a secret agreement with Russia, whose designs on the empire’s territory had led the Turks to join forces with Germany and Austria-Hungary in 1914. By its terms, Russia would annex the Ottoman capital of Constantinople and retain control of the Dardanelles (the crucially important strait connecting the Black Sea with the Mediterranean) and the Gallipoli peninsula, the target of a major Allied military invasion begun in April 1915. In return, Russia would agree to British claims on other areas of the former Ottoman Empire and central Persia, including the oil-rich region of Mesopotamia.