On 23 October 1916 at Hamra in Wadi Safra, Faisal met Captain T. E. Lawrence, a junior British intelligence officer from Cairo. Lawrence, who envisioned an independent post-war Arabian state, sought the right man to lead the Hashemite forces and achieve this. In 1916–18, Faisal headed the Northern Army of the rebellion that confronted the Ottomans in what was to later become western Saudi Arabia, Jordan and Syria. In 1917, Faisal, desiring an empire for himself instead of conquering one for his father, attempted to negotiate an arrangement with the Ottomans under which he would rule the Ottoman vilayets of Syria and Mosul as an Ottoman vassal. In December 1917 Faisal contacted General Djemal Pasha declaring his willingness to defect to the Ottoman side provided they would give him an empire to rule, saying the Sykes–Picot agreement had disillusioned him in the Allies and he now wanted to work with his fellow Muslims. Only the unwillingness of the Three Pashas to subcontract ruling part of the Ottoman Empire to Faisal kept him loyal to his father when it finally dawned on him that the Ottomans were just trying to divide and conquer the Hashemite forces. In his book Seven Pillars of Wisdom, Lawrence sought to put the best gloss on Faisal's double-dealing as it would contradict the image he was seeking to promote of Faisal as a faithful friend of the Allies betrayed by the British and the French, claiming that Faisal was only seeking to divide the "nationalist" and "Islamist" factions in the ruling Committee of Union and Progress (CUP). The Israeli historians Efraim Karsh and his wife Inari wrote that the veracity of Lawrence's account is open to question given that the major dispute within the CUP was not between the Islamist Djemal Pasha and the nationalist Mustafa Kemal as claimed by Lawrence, but rather between Enver Pasha and Djemal Pasha. In the spring of 1918, after Germany launched Operation Michael on 21 March 1918, which appeared for a time to foreordain the defeat of the Allies, Faisal again contacted Djemal Pasha asking for peace provided that he be allowed to rule Syria as an Ottoman vassal, which Djemal confident of victory declined to consider. After a 30-month-long siege, he conquered Medina, defeating the defense organized by Fakhri Pasha and looting the city. Emir Faisal also worked with the Allies during World War I in their conquest of Greater Syria and the capture of Damascus in October 1918. Faisal became part of a new Arab government at Damascus, formed after the capture of that city in 1918. Emir Faisal's role in the Arab Revolt was described by Lawrence in Seven Pillars of Wisdom. However, the accuracy of that book, not least the importance given by the author to his own contribution during the Revolt, has been criticized by some historians, including David Fromkin.