During the 1948 Palestine war, more than 700,000 Palestinian Arabs – about half of Mandatory Palestine's predominantly Arab population – were expelled or fled from their homes. Expulsions and attacks against Palestinians were carried out by the Zionist paramilitaries Haganah, Irgun, and Lehi, which merged to become the Israel Defense Forces after the establishment of Israel part way through the war. The expulsion and flight was a central component of the fracturing, dispossession, and displacement of Palestinian society, known as the Nakba.Honaida Ghanim, Poetics of Disaster: Nationalism, Gender, and Social Change Among Palestinian Poets in Israel After Nakba, International Journal of Politics, Culture, and Society March 2009 Vol. 22, No. 1 pp.23-39 p.37 Stern, Yoav (13 May 2008). "Palestinian refugees, Israeli left-wingers mark Nakba" . Haaretz. Nakba 60 , BADIL Resource Center for Palestinian Residency and Refugee Rights; Cleveland, William L. A History of the Modern Middle East, Boulder, CO: Westview Press, 2004, p. 270.

Dozens of massacres targeting Arabs were conducted by Israeli military forces and between 400 and 600 Palestinian villages were destroyed. The Israeli military operated labor camps for captured Palestinians, most of whom were civilians. Village wells were poisoned in a biological warfare programme, properties were looted to prevent Palestinian refugees from returning, and some sites were renamed.

The precise number of Palestinian refugees, many of whom settled in Palestinian refugee camps in neighboring states, is a matter of dispute, although the number is around 700,000, being approximately 80 percent of the Arab inhabitants of what became Israel.Masalha, Nur (1992). Expulsion of the Palestinians. Institute for Palestine Studies, this edition 2001, p. 175. About 250,000–300,000 Palestinians fled or were expelled during the 1947–1948 civil war in Mandatory Palestine, before the termination of the British Mandate on 14 May 1948. The desire to prevent the collapse of the Palestinians and to avoid more refugees are cited as one of the reasons for the 1948 Arab–Israeli War.Gelber 2006, p. 137: "Drawn into the war by the collapse of the Palestinians and the ALA, the Arab governments' primary goal was preventing the Palestinians' total ruin and the flooding of their own countries by more refugees."

Although the causes of the 1948 Palestinian exodus remain a significantly controversial topic in public and political discourse, with a prominent amount of denialism regarding the responsibility of Israeli/Yishuv forces, most scholarship today agrees that expulsions and violence, and the fear thereof, were the primary causes. Scholars widely describe the event as ethnic cleansing,Shavit, Ari. "Survival of the Fittest? An Interview with Benny Morris" . Logos. Winter 2004 although some disagree.Benny Morris (21 February 2008). "Benny Morris on fact, fiction, & propaganda about 1948". The Irish Times, reported by Jeff Weintraub Factors involved in the exodus include direct expulsions by Israeli forces; destruction of Arab villages; psychological warfare including terrorism; massacres such as the widely publicized Deir Yassin massacre, which caused many to flee out of fear; crop burning; typhoid epidemics in some areas caused by Israeli well-poisoning;Benny Morris, Benjamin Z. Kedar, 'Cast thy bread': Israeli biological warfare during the 1948 War Middle Eastern Studies 19 September 2022, pages =1-25 p.8:'The SHAI, in its report from the end of June 1948 on the causes of the Arab flight from Palestine, mentioned 'the typhus epidemic' as 'an exacerbating factor in the evacuation' in certain areas. 'More than the disease itself, it was the panic induced by the rumours of the spread of the disease in the area that was a factor in the evacuation', stated the report. In its site-by-site breakdown of the Arab flight, the report mentioned 'harassment [by the Haganah] and the typhus epidemic' as the causes of the partial exodus of the population from Acre on 6 May.' and the collapse of Palestinian leadership including the demoralizing impact of wealthier classes fleeing.J.P.D. Dunbabin, The Post-Imperial Age: The Great Powers and the Wider World, Routledge 2014 pp.256-258.Later, a series of land and property 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. The existence of the Israeli Law of Return allowing for immigration and naturalization of any Jewish person and their family to Israel, while a Palestinian right of return has been denied, has been cited as evidence for the charge that Israel practices apartheid.Human Rights Watch. "A Threshold Crossed," 27 April 2021. A Threshold Crossed .Amnesty International. "Israel's Apartheid against Palestinians: A Cruel System of Domination and a Crime against Humanity," 1 February 2022. Israel's Apartheid against Palestinians . The status of the refugees, particularly whether Israel will allow them to return to their homes, or compensate them, are key issues in the ongoing Israeli–Palestinian conflict.

History The history of the Palestinian exodus is closely tied to the events of the war in Palestine, which lasted from 1947 to 1949, and to the political events preceding it. The first phase of that war began on 30 November 1947,Benny Morris, 1948: A History of the First Arab–Israeli War, p. 77, Yale University Press, 2008. a day after the United Nations adopted the Partition Plan for Palestine, which split the territory into Jewish and Arab states, and an international Jerusalem.

In September 1949, the United Nations Conciliation Commission for Palestine estimated 711,000 Palestinian refugees existed outside Israel, with about one-quarter of the estimated 160,000 Palestinian Arabs remaining in Israel as "internal refugees".

December 1947 – March 1948 In the first few months of the civil war, the climate in the Mandate of Palestine became volatile, although throughout this period both Arab and Jewish leaders tried to limit hostilities. According to historian Benny Morris, the period was marked by Palestinian Arab attacks and Jewish defensiveness, increasingly punctuated by Jewish reprisals. Simha Flapan wrote that attacks by the Irgun and Lehi resulted in Palestinian Arab retaliation and condemnation.Flapan, 1987, p. 95; also quoted by Finkelstein, 1995, p. 82. Jewish reprisal operations were directed against villages and neighborhoods from which attacks against Jews were believed to have originated.

The retaliations were more damaging than the provoking attack and included killing of armed and unarmed men, destruction of houses and sometimes expulsion of inhabitants. The Zionist groups of Irgun and Lehi reverted to their 1937–1939 strategy of indiscriminate attacks by placing bombs and throwing grenades into crowded places such as bus stops, shopping centres and markets. Their attacks on British forces reduced British troops' ability and willingness to protect Jewish traffic. General conditions deteriorated: the economic situation became unstable, and unemployment grew.Gelber, p. 75. Some Palestinian Arab leaders sent their families abroad.

Yoav Gelber wrote that the Arab Liberation Army embarked on a systematic evacuation of non-combatants from several frontier villages in order to turn them into military strongholds.(Gelber, p. 79) Arab depopulation occurred most in villages close to Jewish settlements and in vulnerable neighborhoods in Haifa, Jaffa and West Jerusalem. The more impoverished inhabitants of these neighborhoods generally fled to other parts of the city. Those who could afford to flee further away did so, expecting to return when the troubles were over. By the end of March 1948 thirty villages were depopulated of their Palestinian Arab population.Ilan Pappé, 2006 Approximately 100,000 Palestinian Arabs had fled to Arab parts of Palestine, such as Gaza, Beersheba, Haifa, Nazareth, Nablus, Jaffa and Bethlehem.

Some had left the country altogether, to Jordan, Lebanon and Egypt. Other sources speak of 30,000 Palestinian Arabs.Glazer, p. 104. Many of these were Palestinian Arab leaders and middle- and upper-class Palestinian Arab families from urban areas. Around 22 March, the Arab governments agreed that their consulates in Palestine would issue entry visas only to old people, women, children and the sick. On 29–30 March the intelligence service of Haganah, the main Zionist paramilitary, reported that "the Arab Higher Committee was no longer approving exit permits for fear of [causing] panic in the country."Morris, 2004, p. 137, quoting Haganah Archive (HA) 105\257.

The Haganah was instructed to avoid spreading the conflagration by stopping indiscriminate attacks and provoking British intervention.

On 18 December 1947, the Haganah approved an aggressive defense strategy, which in practice meant a limited implementation of "Plan May"; this, also known as "Plan Gimel" or "Plan C",Ruling Palestine, A History of the Legally Sanctioned Jewish-Israeli Seizure of Land and Housing in Palestine. COHRE & BADIL, May 2005, p. 27. produced in May 1946, was the Haganah master plan for the defence of the Yishuv in the event that, the moment the British were gone, new troubles broke out. Plan Gimel included retaliation for assaults on Jewish houses and roads.Excerpts from the book The Ethnic Cleansing of Palestine by Ilan Pappé. Oneworld Publications, 2006.

In early January the Haganah adopted Operation Zarzir, a scheme to assassinate leaders affiliated to Amin al-Husayni, placing the blame on other Arab leaders, but in practice few resources were devoted to the project, and the only attempted killing was of Nimr al Khatib.

The only authorised expulsion at this time took place at Qisarya, south of Haifa, where Palestinian Arabs were evicted and their houses destroyed on 19–20 February 1948. In attacks that were not authorised in advance, several communities were expelled by the Haganah and several others were chased away by the Irgun.

According to Ilan Pappé, the Zionists organised a campaign of threats, consisting of the distribution of threatening leaflets, "violent reconnaissance" and, after the arrival of mortars, the shelling of Arab villages and neighborhoods. Pappé also wrote that the Haganah shifted its policy from retaliation to offensive initiatives.

During the "long seminar", a meeting of Ben-Gurion with his chief advisors in January 1948, the main point was that it was desirable to "transfer" as many Arabs as possible out of Jewish territory, and the discussion focussed mainly on the implementation. The experience gained in a number of attacks in February 1948, notably those on Qisarya and Sa'sa', was used in the development of a plan detailing how enemy population centers should be handled. According to Pappé, Plan Dalet was the master plan for the expulsion of the Palestinians. According to Gelber, Plan Dalet instructions were to expel conquered villagers outside the borders of the Jewish state if met with resistance; if no resistance, the residents could stay put, under military rule.

Palestinian belligerency in these first few months was "disorganised, sporadic and localised and for months remained chaotic and uncoordinated, if not undirected". Husayni lacked the resources to mount a full-scale assault on the Yishuv, and restricted himself to sanctioning minor attacks and to tightening the economic boycott. The British claimed that Arab rioting might well have subsided had the Jews not retaliated with firearms.