The Ottoman Empire's entry into World War I occurred on October 29, 1914 when ships of the Ottoman navy shelled Odessa (Russian Navy Base at the Chrimean peninsula). Their entry threatened Russia's Caucasian territories and Britain's communications with India and the East via the Suez Canal.
1914: The first battles were on the Mesopotamian Campaign, which was opened during the 1914. It was fought in Mesopotamia mainly in the Tigris River valley region of what is now Iraq and included battles on the Persian Gulf coast, Basra, numerous struggles around Kut, and Baghdad.
The Caucasus Campaign was fought in the Caucasus and eastern-Anatolia. The Ottoman Empire in Battle of Sarikamis had a defeat in December-November.
1915: Initially the Ottomans were successful in repelling enemy incursions in Mesopotamia. However after the disastrous Siege of Kut things reversed.
The Russians went on the offense in the Caucasus. The mountains were very high, which made the military movement very difficult, but Russians gained significant achievements.
April 25 sets the Dardanelles Campaign. In Australia, New Zealand and Newfoundland it is known simply as Gallipoli. A combined British and French operation was mounted in order to eventually capture the Ottoman capital of Constantinople (Istanbul). The campaign started with a Naval attempt to force their way past the Dardanelles. When this failed the decision was taken by the Allies to seize the European side of the Dardanelles. The land campaign took place on the Turkish peninsula of Gallipoli in 1915 during the First World War. The land attempt failed, and an estimated 131,000 soldiers were killed and 262,000 wounded.
Starting in 1915, the British based in Egypt tried to incite the Arabs living near the Red Sea and inland (in modern-day Saudi Arabia) to revolt against the Ottoman Empire. The British High Commissioner in Cairo negotiated with Husain Ibn Ali, the Sherif of Mecca. The British government promised to support the restoration of the Caliphate under his leadership… This "deal" was expressed in the McMahon-Hussein Correpondence.
Sinai and Palestine Campaign: The Ottoman Empire launched an attack across the Sinai with the objective of destroying or capturing the Suez Canal. The attack was unsuccessful.
1916: In 1916 the Sherif Hussein Ibn Ali of Mecca began the Arabian revolt. The leadership of this revolt was given to two of his sons: Faisal and Abdullah though the planning and direction for the war was largely the work of Lawrence of Arabia.
The Ottoman Empire launched two attacks across the Sinai with the objective of destroying or capturing the Suez Canal. Both attacks (1915 and 1916) were unsuccessful, though not very costly by the standards of the Great War. The British then went on the offensive and attacked east into Palestine. Two failed attempts to capture the Ottoman fort of Gaza resulted in sweeping changes to the British command and the arrival of General Allenby, along with many reinforcements.
The British and French governments concludes a secret agreement in May 1916 concerning the future of the Middle East. It’s often called the Sykes-Picot Agreement.
1917: British Empire forces reorganized and captured Baghdad in March 1917 in the Mesopotamian Campaign. When Russia withdrew from the war in 1917 the Ottoman Empire managed to regain the prewar territories under the Treaty of Brest-Litovsk.
The Arab revolt was a success, aided immensely by General Allenby's conquest of Palestine in 1917. Late in 1917, Allenby's Egyptian Expeditionary Force had smashed the Ottoman defences, captured Gaza and then captured Jerusalem. A representative of the British Government made an agreement with the growing Zionist movement - this "deal" is called the Balfour Document. The victory over the Ottoman Empire in Palestine was widely promoted in the Allied press. The British capture Jerusalem and the surrounding area was strategically of minimal importance, this event was later the key in the creation of Israel as a separate nation in 1948.
1918: The Battle of Megiddo of September 19 - 21, 1918, and its subsequent exploitation, was the culminating victory in British General Edmund Allenby's Palestine Campaign during WWI.
The Turks were taken by surprise when the British attacked Meggido in a sudden storm. The Turkish troops started a full scale retreat, the British bombed the fleeing columns of men from the air and within a week, the Turkish army had ceased to exist as a military force.
Australian Lighthorse troops marched unopposed into Damascus on September 30, 1918. T.E. Lawrence and his Arab troops entered Damascus the next day to receive an "Official" surrender. The war in Palestine was over. The Turkish government signed an armistice on October 28, 1918 and outright surrendered two days later. 600 years of Ottoman rule over the Middle East had come to an end.