But the Foreign Office was engrossed with events in Europe. Among his other achievements while at Bushire was the establishment of the state of Kuwait as an autonomous kaza within the Ottoman Empire by the Anglo-Ottoman Convention of 1913, where he improved relations with local ruler, Mubarak, by opening negotiations with Ibn Saud. The Turks signed a treaty in London on 29 July 1913 concerning Royal Navy patrols in the Persian Gulf littoral, when Cox met then at the Port of Uqair on 15 December 1913. Cox noted their "intractability" and also warned the Foreign and Commonwealth Office about Ibn Saud; the "increased authority of the Wahhabi Chief". Captain Shakespear's letter had passed via Riyadh to the Suez Canal in which his secret War-camp negotiations with Ibn Sa'ud, had revealed the latter's deep hatred of the Turks, who brutalised his people and threatened his ancestral rights. Shortly after his return to India, Sir Percy was sent back to the Persian Gulf as Chief Political Officer with the Indian Expeditionary Force when World War I broke out in August 1914, still with a brief to prevent Turkish entry on the German side. The Islamic Jihad to crush the British and seize Mesopotamia coincided with Turkey's declaration of war in October 1914. Ibn Saud's mortal enemy, Ibn Rashid, was in the Turkish coalition. Cox sent his deputy to protect Ibn Saud, whose army was attacked at the Battle of Jarrab on 19 January 1914. Shakespear was in command of the artillery when he was charged down and killed in the melee. Sir Percy received immediate authorisation to draft a Treaty of Khufaisa with the Wahhabi ruler with the aim of forming a broader Arab alliance. By April 1915 Cox was based at Basrah where he received a significant Treaty between Ibn Saud and his enemy Ibn Rashid; partition of Arabia in a spirited alliance to rid the peninsula of the Ottomans. They finally met on Boxing Day 1915 at Darin, an island of Tarut, in the bay of Qatif, just north of Bahrain, where they signed the Treaty of Darin. Cox was Secretary to the Government of India, its chief civil servant, and third in order of precedence. He was despatched to the Gulf as Chief Political Officer with the rank of honorary major-general. The arrival of General Nixon from Simla was "shabby…jobbing" as the military build-up enclosing India's plan to capture Baghdad troubled the veteran political time-servers, morally responsible to humanity and to civilization.