One of the strategies Gandhi adopted was to work with Muslim leaders of pre-partition India, to oppose the British imperialism in and outside the Indian subcontinent.[90][91] After the World War I, in 1919–22, he won Muslim leadership support of Ali Brothers by backing the Khilafat Movement in favour the Islamic Caliph and his historic Ottoman Caliphate, and opposing the secular Islam supporting Mustafa Kemal Atatürk. By 1924, Atatürk had ended the Caliphate, the Khilafat Movement was over, and Muslim support for Gandhi had largely evaporated.[90][92][91]