In 1948, following the 1947–1948 war in Mandatory Palestine, the Israeli Declaration of Independence sparked the 1948 Arab–Israeli War, which resulted in the 1948 Palestinian expulsion and flight from the land that the State of Israel came to control and subsequently led to waves of Jewish immigration from other parts of the Middle East.

The latter half of the 20th century saw a series of further conflicts between Israel and its neighbouring Arab nations. In 1967, the Six-Day War erupted; in its aftermath, Israel captured and occupied the Golan Heights from Syria, the West Bank from Jordan, and the Gaza Strip and the Sinai Peninsula from Egypt. In 1973, the Yom Kippur War began with an attack by Egypt on the Israeli-occupied Sinai Peninsula.

In 1979, the Egypt–Israel peace treaty was signed, based on the Camp David Accords. In 1993, Israel signed the Oslo I Accord with the Palestine Liberation Organization, which was followed by the establishment of the Palestinian National Authority. In 1994, the Israel–Jordan peace treaty was signed. Despite efforts to finalize the peace agreement, the conflict continues to play a major role in Israeli and international political, social, and economic life.

Declaration of Independence

With the British Mandate of Palestine scheduled to come to an end on 15 May 1948, the governing body of the Jewish community, the Jewish National Council (JNC), on 2 March 1948 began work on the organization of a Jewish provisional government. On 12 April 1948 it formed the Minhelet HaAm (, lit. People's Administration), all of its members being drawn from Moetzet HaAm (People's Council), the temporary legislative body set up at the same time.

On 14 May 1948—the day the last British forces left Haifa—the People's Council gathered at the Tel Aviv Museum and proclaimed the establishment of a Jewish state in Eretz Israel to serve as the homeland for the Jewish people, to be known as the State of Israel.Declaration of Establishment of State of Israel: 14 May 1948: Retrieved 2 June 2012 The meeting was led by David Ben-Gurion, the Executive Head of the World Zionist Organization, Chairman of the Jewish Agency for Palestine, and soon to be first Prime Minister of Israel. The event is celebrated annually in Israel as Independence Day, a national holiday on 5 Iyar of every year according to the Hebrew calendar. After the Declaration, Minhelet HaAm became the Provisional government of Israel, whilst Moetzet HaAm became the Provisional State Council.

Paragraph 13 of the Declaration provides that the State of Israel would be based on freedom, justice and peace as envisaged by the prophets of Israel; it will ensure complete equality of social and political rights to all its inhabitants irrespective of religion, race or sex. However, the Knesset maintains that the declaration is neither a law nor an ordinary legal document.The Proclamation of Independence Knesset website The Supreme Court has ruled that the guarantees were merely guiding principles, and that the declaration is not a constitutional law making a practical ruling on the upholding or nullification of various ordinances and statutes.The Declaration of the Establishment of the State of Israel Israeli Ministry of Foreign Affairs

The Arab–Israeli War

Immediately following the declaration of the new state, both superpower leaders, US President Harry S. Truman and Soviet leader Joseph Stalin, recognized the new state.Herbert Feis. The birth of Israel: the tousled diplomatic bed (1969) online The Arab League members Egypt, Transjordan, Syria, Lebanon and Iraq refused to accept the UN partition plan and proclaimed the right of self-determination for the Arabs across the whole of Palestine. The Arab states marched their forces into what had, until the previous day, been the British Mandate for Palestine, starting the first Arab–Israeli War. The Arab states had heavy military equipment at their disposal and were initially on the offensive (the Jewish forces were not a state before 15 May and could not buy heavy arms). On 29 May 1948, the British initiated United Nations Security Council Resolution 50 declaring an arms embargo on the region. Czechoslovakia violated the resolution, supplying the Jewish state with critical military hardware to match the (mainly British) heavy equipment and planes already owned by the invading Arab states.Martin Van Creveld, Sword and the Olive: A Critical History of the Israeli Defense Force, Public Affairs (1998) 2002 p. 78 On 11 June a month-long UN truce came into effect.

Following independence the Haganah became the Israel Defense Forces (IDF). The Palmach, Etzel and Lehi were required to cease independent operations and join the IDF. During the ceasefire, Etzel attempted to bring in a private arms shipment aboard a ship called "Altalena". When they refused to hand the arms to the government, Ben-Gurion ordered that the ship be sunk. Several Etzel members were killed in the fighting.

Large numbers of Jewish immigrants—many of them World War II veterans and Holocaust survivors—now began arriving in the new state of Israel, and many joined the IDF.

After an initial loss of territory by the Jewish state and its occupation by the Arab armies, from July the tide gradually turned in the Israelis' favour and they pushed the Arab armies out and conquered some of the territory that had been included in the proposed Arab state. At the end of November, tenuous local ceasefires were arranged between the Israelis, Syrians, and Lebanese. On 1 December, King Abdullah announced the union of Transjordan with Arab Palestine west of the Jordan; only Britain recognized the annexation.

Armistice agreements

Israel signed armistices with Egypt (24 February), Lebanon (23 March), Jordan (3 April) and Syria (20 July). No actual peace agreements were signed. With permanent ceasefire coming into effect, Israel's new borders, later known as the Green Line, were established. These borders were not recognized by the Arab states as international boundaries.Green Line: the name given to the 1949 Armistice lines that constituted the de facto borders of pre-1967 Israel — "Glossary: Israel" , Library of Congress Country Studies Israel was in control of the Galilee, Jezreel Valley, West Jerusalem, the coastal plain and the Negev. The Syrians remained in control of a strip of territory along the Sea of Galilee originally allocated to the Jewish state, the Lebanese occupied a tiny area at Rosh Hanikra, and the Egyptians retained the Gaza strip and still had some forces surrounded inside Israeli territory. Jordanian forces remained in the West Bank, where the British had stationed them before the war. Jordan annexed the areas it occupied while Egypt kept Gaza as an occupied zone.

Following the ceasefire declaration, Britain released over 2,000 Jewish detainees it was still holding in Cyprus and recognized the state of Israel. On 11 May 1949, Israel was admitted as a member of the United Nations. Out of an Israeli population of 650,000, some 6,000 men and women were killed in the fighting, including 4,000 soldiers in the IDF (approximately 1% of the population).

Palestinian expulsion and flight

According to United Nations figures, 726,000 Palestinians had fled or were expelled by the Israelis between 1947 and 1949. The precise number of refugees, many of whom settled in refugee camps in neighboring states, is a matter of dispute but around 80 percent of the Arab inhabitants of what became Israel (half of the Arab total of Mandatory Palestine) left or were expelled from their homes.Masalha, Nur (1992). Expulsion of the Palestinians. Institute for Palestine Studies, this edition 2001, p. 175. "In 1948 half of Palestine's ... Arabs were uprooted from their homes and became refugees" Later, a series of laws passed by the first Israeli government prevented Arabs who had left from returning to their homes or claiming their property. They and many of their descendants remain refugees.Kodmani-Darwish, p. 126; Féron, Féron, p. 94. Except in Jordan, the Palestinian refugees were settled in large refugee camps in poor, overcrowded conditions and denied citizenship by their host countries. In December 1949, the UN (in response to a British proposal) established an agency (UNRWA) to provide aid to the Palestinian refugees. It became the largest single UN agency and is the only UN agency that serves a single people.

Establishment years

A 120-seat parliament, the Knesset, met first in Tel Aviv, then moved to Jerusalem after the 1949 ceasefire. In January 1949, Israel held its first elections. The Socialist-Zionist parties Mapai and Mapam won the most seats (46 and 19 respectively). Mapai's leader David Ben-Gurion was appointed prime minister, and formed a coalition that did not include Mapam, who were Stalinist and loyal to the USSR (another Stalinist party, non-Zionist Maki won 4 seats). This was a significant decision because it signaled that Israel would not be in the Soviet bloc. The Knesset elected Chaim Weizmann as the first (largely ceremonial) president of Israel. Hebrew and Arabic were made the official languages of the new state. All governments have been coalitions—no party has ever won a majority in the Knesset. From 1948 until 1977 all governments were led by Mapai and the Alignment, predecessors of the Labour Party. In those years Labour Zionists, initially led by David Ben-Gurion, dominated Israeli politics and the economy was run on primarily socialist lines.

Immigration and the economy From 1948 to 1951, immigration doubled the Jewish population of Israel and left an indelible imprint on Israeli society.Immigrants in Turmoil: Mass Immigration to Israel and its Repercussions in the 1950s and After Dvora Hacohen, Syracuse University Press, 2003 Overall, 700,000 Jews settled in Israel during this period.Benny Morris, Righteous Victims, chap.VI. Some 300,000 arrived from Asian and North African nations as part of the Jewish exodus from Arab and Muslim countries. Among them, the largest group (over 100,000) was from Iraq. The rest of the immigrants were from Europe, including more than 270,000 from Eastern Europe,Tom Segev, 1949. The First Israelis, Owl Books, 1986, p.96. mainly Romania and Poland (over 100,000 each). Nearly all the Jewish immigrants could be described as refugees, but only 136,000 from Central Europe had international certification because they belonged to the 250,000 Jews registered by the allies as displaced after World War II and living in displaced persons camps in Germany, Austria, and Italy.

In 1950 the Knesset passed the Law of Return, which granted to all Jews and those of Jewish ancestry (Jewish grandparent), and their spouses, the right to settle in Israel and gain citizenship. That year 50,000 Yemenite Jews (99%) were secretly flown to Israel. In 1951 Iraqi Jews were granted temporary permission to leave the country and 120,000 (over 90%) opted to move to Israel. Jews also fled from Lebanon, Syria and Egypt.

Between 1948 and 1958, the population of Israel rose from 800,000 to two million. During this period, food, clothes and furniture had to be rationed in what became known as the Austerity Period (Tkufat haTsena). Immigrants were mostly refugees without money or possessions, and many were housed in temporary camps known as ma'abarot. By 1952 more than 200,000 immigrants were living in tents or prefabricated shacks built by the government. Israel received financial aid from private donations from outside the country (mainly the United States).Mishtar HaTsena (in Hebrew), Dr Avigail Cohen & Haya Oren, Tel Aviv 1995 The pressure on the new state's finances led Ben-Gurion to negotiate a controversial reparations agreement with West Germany. During the Knesset debate some 5,000 demonstrators gathered and riot police had to cordon the building.