As the Allied armies started advancing into Palestine in March 1917, Cemal Pasha ordered the deportation of the Jews of Jaffa, and after the discovery of NILI headed by the agronomist Aaron Aaronsohn who spied for the British out of the fear that Unionists would inflict the same fate on Jews as they did upon Armenians, ordered the deportation of all the Jews. However, the British victories over the Ottomans in the autumn of 1917 with Field Marshal Allenby taking Jerusalem on 9 December 1917 saved the Jews of Palestine from being deported.