Öz When Sir Horace Rumbold, the British Minister in Switzerland, succeeded Admiral Sir John de Robeck, on 17 November 1920, as High Commissioner in Istanbul, the Ottoman Empire, a member of the Central Powers, was already defeated by the Entente Powers (the Allies) in the disastrous Great War, and was forced to sign the Armistice of Mondros (Mudros) on 30 October 1918.