As a politician he was a good speaker of Arabic and Turkish. But he knew when to shut up: he kept silent often in the Bedu presence, yet knew when to speak up, which impressed the Arab sensibilities. To Gertrude Bell he became an indispensable and close friend; whom she fondly admired. By 1914, Cox was a champion of Arab nationalism, working closely with Gertrude Bell, and T.E. Lawrence to that end. During April 1916, Kitchener offered a series of blatant bribes up to £2 million via General Halil "to the people of Kut", disgusted Cox left with Leachman's cavalry brigade sent back to Basra. Gertrude Bell reported she was staying with Sir Percy and Lady Cox in March 1916, living next door to the Military GHQ. On 8 March, Cox had returned from Bushire wherefore gathering intelligence. By May, George Lloyd had joined the unit from London because their work was "political not military," the "Egyptian link" being with the new Arab Bureau. Triumph and capture of Baghdad Cox's main priority was to protect and prevent Ibn Saud from joining the Turkish side in the war. He met the Arab Sheikh at Al-Ahsa Oasis where a Treaty was signed guaranteeing a subsidy of £5,000 per month. Cox knew that Sir Mark Sykes was the champion of Sharif Husein, a rival candidate for the desert kingdoms. The delicate diplomatic balance arose as General Maude took Baghdad in March 1917; and Allenby Jerusalem that December. Taking part in the campaigns in Mesopotamia and Palestine, he was promoted to Honorary Major-General in May 1917. During this time he established strong relations with Ibn Saud, the powerful ruler of the Nejd, with whom he had already had dealings while Resident, and when he gained the nickname Kokus. For the next year Cox was of central importance to the Government of Baghdad, living in a large house where he entertained high society Sheikhs; the arrival of Fahad Bey, Sheikh of Amareh, and others instilled confidence in the British Residency. On 8 September 1918, he visited Tehran, for the first time. The negotiations largely completed Cox was installed as Britain's first ambassador at Tehran in November 1918. At the end of hostilities with the Ottoman Empire, Cox was appointed Acting Minister in Tehran, negotiating the Anglo-Persian Agreement. That winter he returned to Europe, attending the Versailles Peace Conference in 1919. Appointment as High Commissioner of