It has been established elsewhere that gaining the Caliphate for the Hāshimite family was a consuming interest for the Sharīf of Mecca, ῌusayn b. ‘Ali, and his son ‘Abdallāh. The desire to take the Caliphate played a cardinal role in his decision to revolt against the Ottomans. As ῌusayn would have it, he was revolting not to establish a kingdom in the ῌidjāz, and not simply a large Arab state, but to establish a replacement Islamic polity, in which the Arabs, led by the Hāshimites, would take their rightful place.
’Taking Back’ the Caliphate: Sharif Husayn ibn `Ali, Mustafa Kemal, and the Ottoman Caliphate