During World War I, the Zionist cause gained some degree of support from Great Britain. In a 1917 letter from British foreign secretary Lord Balfour to Jewish financier Lord Rothschild, the British government expressed a commitment to creating a Jewish homeland in Palestine. This letter is commonly known as the Balfour Declaration. Unfortunately, the British were speaking out of both sides of their mouth, simultaneously promising Arabs their freedom if they helped to defeat the Ottoman (Turkish) Empire, which at that time controlled most of the Middle East (including the modern states of Syria, Lebanon, Jordan, and Iraq, as well as significant portions of Saudi Arabia and northern Africa). The British promised the Arabs that they would limit Jewish settlement in Palestine mere months after the Balfour Declaration expressed support for "the establishment in Palestine of a national home for the Jewish people."
After World War I, Palestine was assigned to the United Kingdom as a mandated territory by the League of Nations. The Palestinian Mandate initially included the lands that are now Israel and Jordan, but all lands east of the Jordan River were later placed into a separate mandate known as Transjordan (now the nation of Jordan). The document creating the Palestinian mandate incorporated the terms of the Balfour Declaration, promising the creation of a national Jewish homeland within the mandated territory. Although Arab leaders were initially willing to give Palestine to the Jews if the rest of the Arab lands in the Middle East were free, the Arabs living in Palestine vigorously opposed Jewish immigration into the territory and the idea of a Jewish homeland. It is around this time that the idea of Palestinian nationality (distinct from Arab nationality generally) first begins to appear. There were many riots in the territory, and the British came to believe that the conflicting claims were irreconcilable. In 1937, the British recommended partition of the territory.
The Holocaust brought the need for a Jewish homeland into sharp focus for both Jews and for the rest of the world. The Jews who tried to flee Nazi Germany were often turned back due to immigration limitations at the borders of every country, including the United States, Britain and Palestine. Many of those who were sent back to Germany ended up in death camps where they were systematically murdered.
The British were unable to come up with a solution that would satisfy either Arabs or Jews, so in 1947, they handed the problem to the newly-founded United Nations, which developed a partition plan dividing Palestine into Jewish and Arab portions. The plan was ratified in November 1947. The mandate expired on May 14, 1948 and British troops pulled out of Palestine. The Jews of Palestine promptly declared the creation of the State of Israel, which was recognized by several Western countries immediately.
