After World War I Hussein refused to ratify the Treaty of Versailles, in protest at the Balfour Declaration and the establishment of British and French mandates in Syria, Iraq, and Palestine. He later refused to sign the Anglo-Hashemite Treaty and thus deprived himself of British support when his kingdom was invaded by Ibn Saud. In March 1924, when the Ottoman Caliphate was abolished, Hussein proclaimed himself Caliph of all Muslims. In October 1924, facing defeat by Ibn Saud, he abdicated and was succeeded as king by his eldest son Ali. His sons Faisal and Abdullah were made rulers of Iraq and Transjordan respectively in 1921.