When the Ottoman Empire entered into World War I, the British feared for the safety of the Persian Gulf oil facilities. To protect their facilities, the British decided to capture the Ottoman-controlled section of the Persian Gulf coast. The Fortress of Fao was the main Ottoman fortress on the Persian Gulf coast. The British assigned Indian Expeditionary Force D (IEF D) which consisted of the 6th (Poona) Division led by Lieutenant General Arthur Barrett, with Sir Percy Cox as Political Officer.