With the break-up of the Ottoman Empire at the end of World War I, the League of Nations created the French Mandate of Syria and British Mandate of Palestine. Approximately 90% of the was east of the Jordan River and was known as "Transjordan". In 1921, the British gave semi-autonomous control of Transjordan to the future King Abdullah I of Jordan, of the Hashemite family. Abdullah I continued to rule until a Palestinian Arab assassinated him in 1951 on the steps of the Mosque of Omar. At first he ruled "Transjordan", under British supervision until after World War II. In 1946, the British requested that the United Nations approve an end to British Mandate rule in Transjordan. Following this approval, the Jordanian Parliament proclaimed King Abdullah as the first ruler of the Hashemite Kingdom of Jordan.
In 1950, Jordan annexed the West Bank, which had been under its control since the armistice that followed the 1948 Six-Day War. The annexation was recognized only by the United Kingdom (de facto in the case of East Jerusalem).
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