After World War II, continuous Zionist pressure to relocate Jewish survivors of the Holocaust in Palestine caused difficulties for the British authorities before the international community, since they still rigorously applied the policies against further Jewish immigration outlined in the 1939 White Paper. The United Nations proposed a two-state solution, with a Jerusalem/Bethlehem enclave internationalized and adopted a Partition Plan on 29 November 1947. The Plan was accepted by Yishuv but rejected by the Arab League representing the Arab states. A civil war broke out immediately in Palestine as British troops began evacuating the country.
Violence intensified. In February, Arab volunteers entered Palestine. The Jewish sector of Jerusalem became isolated. In April, the Haganah took the offensive and defeated Arab Palestinians and volunteers, and took control of different mixed localities. A massive exodus of Palestinian Arabs began.
Israel declared its independence on May 14, 1948. Several Arab armies entered Palestine. After six weeks of heavy fighting, particularly around Jerusalem, all parties agreed to a truce. This was used by Israel to reinforce her forces, and after the truce Israel took the initiative and defeated the Arab armies. By the conclusion of the 1948 Arab-Israeli War, Israel had greatly expanded its borders and signed ceasefire agreements with all its Arab neighbors.
An exodus of Palestinian Arabs from Israel occurred during this war. Simultaneously, Jews exited Jerusalem by force, and Jewish residents of nearby villages and settlements, such as K'far Etzion, were massacred by Arab troops. Jews were not allowed to live in or visit Jerusalem from 1948-1967, and Jewish holy places in Jerusalem were vandalized during this period.
The causes are a source of dispute among historians: Some claim that the Palestinian villagers were forcibly expelled and others, that the villagers fled in fear before Israeli forces arrived. Whatever the reasons behind it, this exodus created the Palestinian refugee problem, which has remained unsolved. Many abandoned properties and villages were resettled by Jewish refugees from Europe and Arab lands. (See also: Aliyah Bet, Berihah, Sh'erit ha-Pletah, Jewish exodus from Arab lands)
One factor in the persistence of the Arab refugee problem was the refusal of any Arab government except Jordan to offer the Palestinian Arabs citizenship. Whereas other much larger refugee problems after World War II were eventually solved, this one persisted. Palestinians were defined as those who lived in Palestine between 1946-1948 or their descendants by the United Nations Relief Works Agency (UNRWA) which was created especially for the Palestinians. Aid was given by the United Nations, based on population figures, and refugee camps that had sprouted up in Egypt, Lebanon, Jordan grew as did the Palestinian population. Because the Palestinians did not become Egyptian, Lebanese, or Israeli, the number of Palestinian Arabs increased to several million.
Period 1949-1967 :
By the end of 1949, only 150 123 Palestinians remained within Israel. For this reason, the Israeli-Palestinian Conflict took a back seat to the broader Arab-Israeli Conflict during this time.
Palestinians played a crucial role in the Egyptian-Israeli conflict during this time. Beginning in 1950, Egypt began using fedayeen to conduct a war of proxy against Israel. These units of Palestinians—often trained and equipped by Egypt—would infiltrate across what was then the Israeli-Egyptian border at Gaza, and conduct guerilla raids against Israeli targets (mostly civilian in nature). In the first five years of the 1950s, "884 Israelis were wounded or killed by" Palestinian fedayin trained and sent into Israel by the Egyptians. The fedayin attacks was cited as being among the factors leading up to the Israeli decision to participate in the Sinai Campaign in 1956.
The scope of the Israeli-Palestinian conflict again broadened after Israel conquered the West Bank from Jordan and the Gaza Strip from Egypt during the Six-Day War.