‘Cast Thy Bread’: Israeli Biological Warfare During the 1948 War

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This article describes Israel’s bacteriological warfare campaign during the first Arab-Israeli war of 1948. Over the decades following that war rumours circulated that Israel had used bacteria, alongside conventional weaponry, in its battle against Palestine’s Arabs and the surrounding Arab states.

The declassification of files in the Israeli military archives, our discovery of a crucial letter in private hands, and the publication of a handful of memoirs relating to 1948 have enabled us to bridge the divide between rumour and fact; to explain the campaign’s origins; to reconstruct its stages, beginning in April 1948; to identify who was involved – including Israel’s prime minister, David Ben-Gurion and the Israeli army’s de facto chief of general staff, Yigael Yadin, as well as leading Israeli scientists – and who actively opposed it; and to delineate and assess what the campaign actually achieved or failed to achieve. In sum, this study helps to understand various aspects of the 1948 War.


Following the first Arab-Israeli war, of 1948, rumours surfaced that the typhoid epidemic that struck the Arab town of Acre days before its fall on 18 May, had been caused by bacteria poured into the town’s water works by agents of the Haganah, the main Jewish militia. Later that month, the Egyptian government announced that it had caught two ‘Zionist’ operatives as they were trying to infect wells near Egyptian-occupied Gaza. The two episodes have been mentioned in several books1 and discussed by Sara Leibowitz-Dar, Avner Cohen and Salman Abu Sitta in articles published some twenty years ago, based mainly on interviews.2 But real-time Israeli documentation of the country’s clandestine biological warfare in 1948 remained closed to researchers and over the years government agencies have tried to suppress information on the subject. For example, crucial words in Ben-Gurion’s diary for 1948, published in 1982 by the Defense Ministry Press, were deleted.3

The code name of the biological warfare operation – ‘Cast Thy Bread’ (in Hebrew: shallah lahmekha, from ‘cast thy bread upon the waters’ (shallah lahmekha ʿal pney ha-mayim, Ecclesiastes 11:1)) is partially mentioned, as shallah, in a memoir published in 2000 by Arieh Aharoni, a Palmah officer in 1948, who unequivocally asserted that the operation aimed at poisoning water used by the invading Egyptian army.4

The full code name is mentioned in the 2003 article by Abu Sitta, who received the information from Israeli military historian Uri Milstein.5 Once aware of the code name, we were able to trawl through hundreds of files in the Israel Defense Forces and Defense Ministry Archive (henceforward, IDFA), produced by military units operating in areas that we thought might have been targeted in the operation, and to identify relevant documents. Israel Government censors, apparently unaware of the significance of the code name and confused by the cryptic language generally used, let them through. Furthermore, we found a crucial letter by David Ben-Gurion from 14 May 1948, preserved in a private archive, and used unpublished – and highly revealing – interviews with two key figures, Ephraim Katzir (Katchalsky) and Shemarya Guttman. In addition, a privately printed memoir by Rafi Kotzer, commander of an elite Israel Defense Forces (the Israeli army, henceforward IDF) unit in 1948, also supplied useful information. Taken together, these documents revealed that the Acre and Gaza episodes were merely the tip of the iceberg in a prolonged campaign, designed initially to prevent Palestinian Arab militiamen from returning to their villages from which they harassed Jewish settlements and road traffic and, later, to hinder the Arab states’ armies that invaded Palestine on 15 May 1948.

In the following pages we offer a step-by-step reconstruction of Israel’s top secret biological warfare campaign during the 1948 War and describe how, if at all, it affected the war-making. Along the way, we shall show how dissenting voices, at various levels of government and army, hampered the unfolding operations. However, due to the fragmentary nature of the available sources, ours remains a skeletal reconstruction. For instance, we were unable to access any material on the science side of the Cast Thy Bread campaign: on how and what equipment and knowledge of biological warfare was acquired in Europe and the United States and how the requisite germs were acquired or produced and weaponized and where this was done. At several points, we have been constrained to offer assumptions, all duly presented as such.

In April 1948 the gloves came off. Since 29 November 1947, when the UN General Assembly passed Resolution 181, proposing the partition of Palestine into two states, and the Palestine Arabs had launched hostilities, the Jews had been on the defensive.

They had accepted the partition resolution – and Palestine’s Arabs had not. Backed by the surrounding Arab states, their militiamen, based in the country’s 750-odd villages and towns, continuously attacked Jewish settlements and convoys, causing more than 1000 deaths. The Jews periodically retaliated. The British, who had conquered the country from the Turks and ruled it since 1917/18, were scheduled to depart on 15 May 1948, and the Arab states had announced that they would invade when the British left. For the country’s 650,000-strong Jewish community – called collectively the Yishuv (Hebrew for ‘the settlement’) – the future looked grim. March 1948 had seen a series of major military setbacks, with large Haganah convoys destroyed in ambushes along the roads, mostly around Jerusalem. The Jews feared that, should the Arabs win, a second Holocaust would result, a bare three years after the first had ended.6

On the night of 31 March, David Ben-Gurion, the leader of the Yishuv and its de facto defence minister, in political charge of the Haganah, summoned an emergency meeting of his military aides. He was especially worried about the fate of Jerusalem’s 100,000 Jews. The city’s western, Jewish half was besieged by Arab militiamen, who dominated the Tel Aviv-Jerusalem road, the Jews’ main supply line.

Ben-Gurion insisted that the Haganah secure the road and push through a number of large supply convoys; the militia’s commanders – who would have preferred that their crack troops engage the Arabs elsewhere – reluctantly agreed. As it turned out, Operation Nahshon, launched in effect on 3 April with the capture of the Arab hilltop village of al-Qastal just west of Jerusalem, marked the Yishuv’s turn to the offensive and was the first in a six-week-long series of country-wide operations in which the Palestinian Arab militias were crushed and the Yishuv braced for the impending pan-Arab invasion.

The invasion, by the armies of Egypt, Jordan, Iraq and Syria, duly began at sun-up on 15 May. Nahshon was the first operation in which the Yishuv captured and held – as it turned out, permanently – swathes of Arab-inhabited territory designated in the United Nations (UN) partition resolution for Arab sovereignty.

A week into Nahshon, after the capture of a handful of sites, the Haganah leadership decided on a series of measures to prevent the return of the Arabs – crucially, militiamen – to their villages on either side of the Tel Aviv-Jerusalem road. The main measure adopted was levelling the villages, partially or completely; this usually included the destruction of the village wells. Indeed, well destruction had become routine in the tit-for-tat characterising the first months of the war. For example, a Haganah operational logbook, under ‘21.2.48′, stated: ‘Last night the Arabs blew up the well of [Kibbutz] Kiryat ʿAnavim [just west of Jerusalem]. Part of the building was destroyed.

In the retaliatory strike immediately carried out, a unit of the 6th Battalion attacked [the nearby Arab village of] Bayt Naquba and blew up the village spring.’7 A similar case was recorded a month before: a Jewish convoy travelling through the Arab village of Burayr in the south was ambushed. The convoy stopped, the troops dismounted and then ‘blew up the village well’.8

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Articles by: Benny Morris and Benjamin Z. Kedar

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