Operation Cast Thy Bread was a top-secret biological warfare operation conducted by the Haganah and later the Israel Defense Forces that began in April 1948, during the 1948 Palestine war. The Haganah used typhoid bacteria to contaminate drinking water wells in violation of the 1925 Geneva Protocol. Its objective was to frighten and prevent Palestinian Arabs from returning to villages captured by the Yishuv and make conditions difficult for Arab armies attempting to retake territories. The operation resulted in severe illness among local Palestinian citizens. In the final months of the 1948 Arab–Israeli War, Israel gave orders to expand the biological warfare campaign into neighboring Arab states such as Egypt, Lebanon, and Syria, but they were not carried out. Israeli prime minister David Ben-Gurion and IDF chief of general staff Yigael Yadin oversaw and approved the use of biological warfare.[1][2]
Abba Eban, representative of the Jewish Agency for Palestine, strongly denied the operation and sought to block further investigations by accusing the Arab states of engaging in "antisemitic incitement". Operation Cast Thy Bread did not achieve the crippling effects its advocates had hoped for, and was discontinued by December 1948.[3] In July 1948, the Palestinian Arab Higher Committee reported to the United Nations several war crimes committed by Zionist forces, including the use of "bacteriological warfare".[4]
According to Avner Cohen, the Haganah's chief operations officer Yigael Yadin dispatched a microbiology student named Alexander Keynan to Jaffa on 18 February 1948 to set up a unit known as HEMED BEIT. Keynan and future Israeli president Ephraim Katzir "planned various activities, to get a sense what chemical and biological weapons are and how we could build a potential should there be a need for such a potential".[5] Their main objective was to create a weapon that could blind people.[6]
In April 1948, David Ben-Gurion ordered an official of the Jewish Agency in Europe to find Eastern European Jewish scientists who could "either increase the capacity to kill masses or to cure masses; both are important".[7][5] According to Milton Leitenberg, that "capacity" meant chemical and biological weapons, which could be used for either offense or defense.[7] One of the scientists recruited was an epidemiologist and colonel in the Red Army called Avraham Marcus Klingberg.[4]
Benny Morris reported that Israeli soldiers transported typhoid germs in bottles to the southern front. British, Arab, and Red Cross documents reveal that Zionist forces introduced poison into wells in Acre and Eilabun in Galilee, leading to severe illness among dozens of local residents. Acre, which was allocated to a future Arab state by the United Nations Partition Plan for Palestine, heavily relied on its aqueduct for water. The contamination of these wells triggered a typhoid epidemic and "a state of extreme distress" among the inhabitants, as noted by the mayor of Acre on 3 May. The Carmeli Brigade of the Haganah allegedly used a biological weapon in the battle of Acre in May 1948.[5] In the following month, an Israeli intelligence report concluded that deliberately inducing the epidemic had played a significant role in the rapid fall of Acre to Haganah forces.[1]
The Haganah had also poisoned the depopulated Palestinian Arab village of Bayt Mahsir and water sources in Palestinian neighborhoods in Jerusalem.[3]
The operation was carried out by ordinary IDF soldiers and later the Mista'arvim, an undercover unit specialized in sabotage operations within enemy territory, disguising themselves as Palestinians.[8]
In May 1948, during Operation Shalach, four Israeli Special Forces soldiers, disguised as Arabs, attempted to poison the local water supply in Gaza to impede the advance of the Egyptian army. They infiltrated the city with tubes containing typhoid germs. The Israeli soldiers were captured by Egyptian soldiers near water wells on 23 May and subsequently executed by an Egyptian military court on 22 August 1948.[9][10][11] Egypt complained about the incident to the United Kingdom, but the Foreign Office decided it was best to stay uninvolved. However, one British official remarked that the situation was so "obnoxious" that Britain might consider expressing its "disgust" to the Israelis if the opportunity arose.[12]
On 22 July 2024, the Arab Higher Committee presented a formal complaint to the United Nations of the various war crimes committed by "Palestinian Jews", including engaging in "bacteriological warfare". The committee accused the Zionists of having constructed laboratories in Palestine for biological warfare purposes and of having "planned and prepared for the use of bacteriological warfare" over a protracted period of time. The committee also suggested that there was "some" inconclusive evidence linking the cholera outbreaks in Egypt and Syria in late 1947 and early 1948, respectively, to actions taken by Zionist forces.[4]
Israel vehemently denied the accusations of well poisoning and biological warfare against Palestinian Arabs, denouncing the Egyptian allegations as "wicked libel". Israel stated that the four Israeli soldiers captured by Egyptian troops in Gaza were there to observe military activities and evaluate the morale of the Arab population.[4] Abba Eban denied the well poisoning operation and attempted to block further investigations by accusing the Arab states of engaging in "antisemitic incitement".[3]
The Zionists injected typhoid in the aqueduct at some intermediate point which passes through Zionist settlements ... The city of Acre, now burdened by the epidemic, fell easy prey to the Zionists. ... Two weeks later, after their "success" in Acre, the Zionists struck again. This time in Gaza, where hundreds of thousands of refugees had gathered after their villages in southern Palestine were occupied. The end however was different. ... The biological crimes perpetrated against the Palestinians in Acre and Gaza in 1948 are still being enacted today.
[p. 191] Egyptian Ministry of Defense and, later, Israeli historians, contend that Israeli soldiers contaminated Acre's water supply.
[p. 154] Some BW programs relied on extremely crude methods, about as sophisticated as those employed by some terrorist groups or criminals ... The same was true of the reported activities associated with the early Israeli program in 1948.
[p. 31] It is believed that one of the largest operations in this campaign was in the Arab coastal town of Acre, north of Haifa, shortly before it was conquered by the IDF on May 17, 1948. According to Milstein, the typhoid epidemic that spread in Acre in the days before the town fell to the Israeli forces was not the result of wartime chaos but rather a deliberate covert action by the IDF—the contamination of Acre's water supply ... The success of the Acre operation may have persuaded Israeli decisionmakers to continue with these activities. On May 23, 1948, Egyptian soldiers in the Gaza area caught four Israeli soldiers disguised as Arabs near water wells ... It seems that many people knew something about these operations, but both the participants and later historians chose to avoid the issue, which gradually became a national taboo ... Despite the official silence, it appears there is little doubt now about the mission of the failed Gaza operation.
[pp. 19–20] The urbicide of May 1948 directed against the old Crusader city of Acre involved biological warfare, including poisoning of water, Pappé writing that it seems clear from Red Cross reports that the Zionist forces besieging the city injected 'typhoid germs' into the water supply, which led to a 'sudden typhoid epidemic'. There was a similar attempt to 'poison the water supply in Gaza' on 27 May 1948 by injecting typhoid and dysentery viruses into wells; this attempt was fortunately foiled.
[p. 289] As early as April 1948, Ben Gurion directed one of his operatives in Europe (Ehud Avriel) to seek out surviving East European Jewish scientists who could "either increase the capacity to kill masses or to cure masses: both things are important." At that time, that 'capacity' meant chemical and biological weapons ... These were ultimate weapons that could be used either for offense or defense (and the context of the immediate military operations, as well as those that had preceded it, would be the critical factors in that categorization).
[p. 7] Israeli biological warfare activities included Operation Shalach, which was an attempt to contaminate the water supplies of Egyptian Army. Egypt reports capture of four 'Zionists' trying to infect wells with dysentery and typhoid. There are also allegations that a typhoid outbreak in Acre in 1948 resulted from a biological attack and that there were attacks in Egypt in 1947 and in Syria in 1948.
[pp. 73–4] The flame-thrower project was part of a larger unit engaged in developing biological warfare under the directorship of a physical chemist called Ephraim Katzir ... The biological unit he led together with his brother Aharon, started working seriously in February [1948]. Its main objective was to create a weapon that could blind people ... [pp. 100–101] During the siege [of Acre] typhoid germs were apparently injected into the water. Local emissaries of the International Red Cross reported this to their headquarters and left very little room for guessing whom they suspected: the Hagana. The Red Cross reports describe a sudden typhoid epidemic and, even with their guarded language, point to outside poisoning as the sole explanation for this outbreak ... A similar attempt to poison the water supply in Gaza on 27 May was foiled.
A unit had been formed to develop biological weapons, and there is evidence that these were used during 1948 to poison the water supplies of Akka and Gaza with typhoid bacteria.
Israeli desperation was such that two Palmah Arab Platoon scouts, David Mizrahi and 'Ezra Afgin (Horin), were sent to Gaza reportedly to poison wells (as well as gather information). They were caught on 22 May near Jibalya with "thermos flasks containing water contaminated with typhoid and diphtheria [or dysentery] germs," according to King Farouk. Mizrahi and Afgin had apparently poured the concoction into one well before being captured and confessing. The two were executed on 22 August. The Egyptians complained to London, but the Foreign Office thought it prudent to "keep out" (though one official minuted that the matter was so "obnoxious" that perhaps, if the opportunity arose, Britain could "express [its] disgust" to the Israelis).