The Israel Defense Forces were born in May 1948, right after David Ben-Gurion proclaimed the state of Israel. The new army was immediately tested as neighboring Arab nations invaded. But the men who filled its ranks weren’t rookies. They came from three paramilitary groups that had been fighting for decades: the Haganah, the Irgun, and Lehi.
To some, they were freedom fighters. To others, terrorists. To understand how these groups came to be, you have to go back to British Mandatory Palestine. Before World War I, the area was part of the Ottoman Empire.
The British took control during the war and soon became committed to making it a homeland for the Jewish people. As Jewish immigration surged in the 1920s and 30s, violence with the local Arab communities spiraled out of control. In April 1920, riots broke out in Jerusalem during a Muslim festival. Five Jews were killed, hundreds were injured.
Four Arabs died too, and seven British soldiers were wounded. The Jewish community, known as the Yishuv, realized they couldn’t rely on the British to protect them. They had to arm themselves. Jewish self-defense groups had existed even before World War I, during the Second Aliyah, when European Jews settled in kibbutzim.
The Bar Giora was founded in 1907, and the Hashomer in 1909. But after the 1920 riots, the Yishuv founded the Haganah, a larger militia that went on the offensive against the British, the Arabs, and anyone else who opposed Zionism. In 1924, a Dutch writer named Jacob Israel de Haan, who advocated for a state where Jews and Arabs would live as equals, was murdered in Jerusalem. In the 1930s, the Irgun, also known as Etzel, split from the Haganah.
There was also the Palmach, an elite unit of the Haganah founded in 1941, meant to defend the Jewish community if the German Wehrmacht advanced into Palestine, and later to take over when the British withdrew in May 1948. The Palmach was set up by a left-wing party, so it was committed to socialism and the kibbutz ethos. That created tension with the right-wing Irgun and Lehi volunteers. But after World War II, nationalist sentiment pushed those differences aside.
The British became the target, and Irgun and Lehi agreed to coordinate with the Haganah. Despite their ideological disagreements, they all shared the same outlook: a military solution. The Irgun and Lehi were inspired by a right-wing variant of Zionism. In the early 20th century, practical Zionism focused on immediate settlement and building infrastructure.
Labor Zionism, or socialist Zionism, wanted to build the Jewish state through socialist principles, especially Jewish labor and collective agriculture in kibbutzim. This left-wing ideology became dominant in the Yishuv. But there was also Revisionist Zionism, founded by Ze’ev Jabotinsky. He believed Zionism must be militant, nationalist, and assertive.
He rejected labor Zionism and demanded a Jewish state on both sides of the Jordan River. “We shall have a Jewish state with or without the consent of the British,” was their slogan. They believed Jews had the right to defend themselves and needed a strong military. Jabotinsky laid the ideological foundation for groups like the Irgun.
The violent events of 1929, when Arabs rioted against Jews in Palestine, caused a split within the Haganah. A man named Abraham Tehomi felt the Haganah wasn’t strong or militaristic enough, so he created a new group called the Irgun. He even tried to get Jabotinsky to support it. The group included young activists like Abraham Stern.
Though they claimed not to be political, most were drawn to Jabotinsky’s vision of Jewish national pride and admired past Jewish heroes. As frustration with British policies grew, the Irgun and later Betar shifted into militant underground groups in the late 1930s, something Jabotinsky himself opposed. They wanted to end dependence on British military protection. Herzl, the founder of political Zionism, had said a Jewish army wasn’t a necessary evil but should be a goal.
People like Stern spoke of sacrifice, not dying of old age in a hospital bed, but taking the last bullet to save the Jewish people. They believed Jews should respond to the growing threat in Europe by building a strong force to defend Jewish life and dignity. The events of 1929 had convinced them that moral arguments alone wouldn’t protect Jews. Only visible strength would gain the world’s respect.
The Irgun also wanted to reinterpret Jewish history to inspire action. Attacks on the British continued during and after World War II. The most well-known was the bombing of the King David Hotel in July 1946, which killed over 90 people. Lehi, better known as the Stern Gang, was a militant Zionist group founded in 1940 by Abraham Stern.
Stern was born in 1907 in Suwałki, then part of the Russian Empire. He moved to Palestine in 1925 and studied at the Hebrew University. Influenced by nationalism, the Bolshevik Revolution, and the rebirth of Poland, he was initially drawn to Jabotinsky’s Revisionist Zionism. But Stern broke away, rejecting any cooperation with the British, whom he viewed as colonial oppressors and an obstacle to a Jewish state.
He placed himself on the extreme right of the Zionist movement, influenced by European radical nationalism and fascist models. He envisioned a Jewish state that was authoritarian, ethnically exclusive, and ruled by a strong, centralized government. Unlike mainstream Zionists who wanted a democratic refuge, Stern imagined Jews holding absolute power with Arabs relegated to second-class status. Under his leadership, Lehi embraced terrorism as a legitimate tool, carrying out assassinations, bombings, and robberies.
Stern admired authoritarian leaders like Mussolini and even Hitler, not for their racial ideology, but for their ruthless methods and power. Lehi even reached out to the Nazis for a possible alliance. Lehi’s most notorious act was the 1944 assassination of Lord Moyne, the British Minister of State for the Middle East. Although Stern was killed in 1942, his uncompromising vision shaped Lehi’s actions throughout the 1940s, leaving a controversial legacy of radical nationalism, Jewish supremacy, and political violence.
When the state of Israel was declared on May 14, 1948, the new country immediately faced invasion by surrounding Arab states. To survive, Israel needed a single, unified army under government control. Prime Minister David Ben-Gurion was determined that Israel must not have competing militias. On May 26, 1948, the provisional government created the Israel Defense Forces, officially merging all three groups into one national army.
The process wasn’t smooth. The integration was particularly difficult with the Irgun. While the Haganah and Lehi agreed more quickly, the Irgun only formally disbanded on June 1, 1948, pledging to hand over weapons and end independent operations. Tension soon erupted with the arrival of the Altalena, an Irgun ship carrying arms and fighters.
Ben-Gurion ordered the ship’s seizure. On June 22, 1948, clashes broke out between Irgun and IDF forces. More than a dozen Irgun members were killed, and the Altalena was shelled and sunk. Though Irgun leader Menachem Begin avoided open rebellion, the crisis exposed deep divisions.
Lehi supported the Irgun and accused Ben-Gurion of surrendering sovereignty, calling for renewed underground resistance and even aligning itself rhetorically with the Soviet Union against imperialist Western powers. Despite attempts to form a common front with the Irgun, Lehi found itself isolated. Suspicious of the new state’s socialist leadership, it doubted whether to pledge loyalty to the IDF at all, insisting allegiance should only be to the freedom of Israel. The Altalena affair highlighted the violent struggle to unify Israel’s armed forces and the lingering ideological rifts among Zionist factions.
Despite the tensions, by late 1948, all three groups had been absorbed, creating a unified military that became the backbone of Israel’s survival. During the Arab-Israeli War of 1948, also known as Israel’s War of Independence, the Jewish militias committed acts of violence and ethnic cleansing against the Arab Palestinian population. Violence and expulsions had already occurred before. On April 9, 1948, Zionist paramilitaries attacked the village of Deir Yassin near Jerusalem.
Jewish militiamen killed at least 107 Palestinian Arab villagers, including women and children. The attack was perpetrated by the Irgun and Lehi, supported by the Haganah and Palmach. This tragedy occurred during the 1947-48 civil war in Mandatory Palestine and was a central component of the Nakba and the 1948 Palestinian expulsion and flight. According to historian Ilan Pappé, ethnic cleansing began in early December 1947 with a series of Jewish retaliatory attacks on local villages and neighborhoods.
Although sporadic, these attacks were severe enough to cause an exodus of nearly 75,000 of the local Arab population. Over 700,000 Arabs eventually fled or were expelled. This is known as the Nakba, which means catastrophe. Other historians argue that Jewish war plans did not aim to expel Palestinians, but that it was a logical consequence of war.
Despite the violent actions, many of the individuals involved in the Jewish militias were eventually integrated into Israeli society. Members played an important role in Israeli politics in the half-century that followed. Yigal Allon, Moshe Dayan, and Yitzhak Rabin were high-ranking members of the Haganah-Palmach. Menachem Begin led the Irgun, and Yitzhak Shamir was a prominent member of the Lehi.
Three of these men, Rabin, Shamir, and Begin, would later become prime ministers of Israel.
