Great Britain decided the Palestine problem was beyond its powers to solve, and referred it to the United Nations. In November, 1947, the UN voted to partition Palestine between the Arabs and Jews, leaving Jerusalem in an international zone. Arab leaders rejected the plan, and fighting broke out. On May 14, 1948, as the British mandate ended, Jewish leaders proclaimed the state of Israel. David Ben-Gurion became the first prime minister.

The new state beat off invasion by the neighboring Arab League countries. Fighting ended in 1949 with Israel occupying part of Jerusalem and a part of Arab Palestine. Israel refused to withdraw and no treaty was signed. Arabs were expelled from the captured areas, creating enormous refugee problems. Many remained in Jordanian refugee camps indefinitely. In 1950 Jordan annexed the remainder of Arab Palestine, including eastern Jerusalem.

In October, 1956, Israel attacked Egyptian bases on the Sinai Peninsula and advanced within 10 miles (16 km) of the Suez Canal. Meanwhile, Great Britain and France moved to seize the canal. The UN stopped the British-French attack and achieved a truce. Israeli forces eventually withdrew.

During the 1960's, tension remained high. There were frequent border clashes, but full-scale war did not break out until June, 1967. In six days, Israel defeated the allied forces of Egypt, Syria, and Jordan and quickly captured the Gaza Strip, the Sinai Peninsula, the Golan Heights, and all Jordanian territory west of the Jordan River (thus gaining full control of Jerusalem). The conflict, known as the Six Day War, was halted by a UN-arranged cease-fire.

Within months the Israelis and Arabs had resumed limited warfare, usually in the form of air strikes and commando raids. There were frequent clashes along the Lebanese border and the Suez Canal. Palestinian extremists launched a worldwide terrorism campaign against Israel and its friends.

Tensions grew until October, 1973, when Egypt and Syria made a full-scale attack against Israel on the Jewish holiday of Yom Kippur. Iraq and Jordan sent troops to assist in what came to be known as the Yom Kippur War. With the support of both the United States and the Soviet Union, the UN effected a cease-fire on the 22nd day of fighting. There were then Egyptian forces in the Sinai and Israeli forces west of the Suez Canal; the Golan Heights were occupied by Israeli forces. Partial Israeli troop withdrawals from Syrian and Egyptian territory were arranged in 1974.

Israel sought a permanent peace settlement with the Arab countries, but made no progress toward such an accord until President Anwar Sadat of Egypt made a visit to Jerusalem in 1977. In 1979 a peace treaty was signed, under which Egypt regained the Sinai in a series of steps ending in 1982. In exchange, Egypt recognized Israel's sovereignty.

Israel's occupation of Jordanian and Syrian lands continued to hamper efforts toward peace with the other Arab countries. Tensions were heightened in 1981 when Israel annexed the Golan Heights and in 1982 when the country invaded and occupied southern Lebanon. Israeli forces withdrew from most of Lebanon in 1985.

During 198791, Israeli control of occupied areas was challenged by an Arab resistance campaign called the intifada (uprising). In 1991, peace talks began between Israel and the Palestine Liberation Organization (PLO), Syria, Jordan, and Lebanon. In a peace agreement in 1994 the PLO agreed to end its conflict with Israel, and Israel gave the PLO limited autonomy over the Gaza Strip and the West Bank town of Jericho. Israel and Jordan also signed a peace treaty.

In September, 1995, Israel's prime minister, Yitzhak Rabin, and PLO chairman Yasir Arafat signed an agreement expanding Arab self-rule in the West Bank. In November Rabin was assassinated by a right-wing Jewish opponent of the pact. In 2000, Israel ended its occupation of southern Lebanon, and there was a marked increase in acts of violence between Palestinians and Israel. Israeli and Palestinian leaders agreed in 2003 to consider a plan for peace supported by the United Nations and several countries, but acts of violence and retaliation continued. Despite Palestinian opposition, Israel began constructing a fence to separate Palestinian areas from other parts of the country. In 2004, the Knesset approved prime minister Ariel Sharon's plan to remove Israeli settlers from Gaza and parts of the West Bank. Palestinians were to assume complete control of these areas.