Also called Hagana Bet; a Jewish paramilitary organization in Palestine formed in 1931 and headed by Abraham Tehomi (formerly Silber) that was organized on a military basis and stressed military training and discipline. In its early years, civilian backing was provided by a broadly based board consisting of representatives of all nonsocialist parties in the Yishuv. The rank and file of the organization consisted overwhelmingly of members of Betar and young Revisionists, but the Revisionist Movement had at that stage no decisive influence over the body. In 1937, Tehomi reached an agreement with the Hagana for the merger of the two defense bodies.
This led to the formation in 1940 of the splinter LEHI or Stern (Gang) Group—named for its founder, Avraham Stern (Yair). Ir-gun asserted that only active retaliation would deter the Arabs. Its ideology, based on the teachings of Vladimir Ze'ev Jabotinsky, was built on the principle that armed Jewish force was the prerequisite for the Jewish state and that every Jew had a natural right to enter Palestine. Irgun's first commander was Robert Bitker, who was succeeded by Moshe Rosenberg and then by David Raziel. Its symbol was a hand holding a rifle over the map of the original Palestine mandate, including Transjordan, with the motto "rak kach" ("only thus"). The Jewish Agency strongly denounced Irgun's "dissident activities," which the British administration countered by suppression and mass arrests. Until May 1939, Irgun's activities were limited to retaliation against Arab attacks. After the publication of the British White Paper of 1939, the British mandatory authorities became Irgun's main target. Another major field of activity was the organization of Aliya Bet (illegal immigration) and helping "illegal" immigrants land safely.
With the outbreak of World War II, Irgun announced the cessation of anti-British action and offered its cooperation in the common struggle against Nazi Germany. Its commander in chief, David Ra-ziel, was killed in Iraq in May 1941 while leading Irgun volunteers on a special mission for the British. Raziel's successor was Yaakov Meridor, who in turn was replaced by Menachem Begin in December 1943, who remained in command until 1948.
In January 1944, Irgun declared that the truce was over and that a renewed state of war existed with the British. Irgun demanded the liberation of Palestine from British occupation. Its attacks were directed against such government institutions as immigration, land registry, income tax offices, and police and radio stations. Limited cooperation was established in the late fall of 1945 between Irgun, LEHI, and Hagana, with the formation of the Hebrew Resistance Movement. Cooperation between the three forces lasted, with occasional setbacks, until August 1946. On July 22 of that year, Irgun blew up the British army headquarters and the secretariat of the Palestine government in the King David Hotel in Jerusalem.
When organized Arab bands launched murderous anti-Jewish attacks after the United Nations adopted the Palestine Partition Plan on 29 November 1947, Irgun vigorously counterattacked. Among these was the capture on 10 April 1948 of the village of Deir Yassin by Irgun and LEHI forces, which resulted in a reported 240 Arab civilian casualties, although recent Palestinian research suggests that the actual number of casualties may have been exaggerated.
When the state of Israel was proclaimed on 14 May 1948, Irgun announced that it would disband and transfer its men to the Israel Defense Forces (IDF). For several weeks, however, until full integration was completed, Irgun formations continued to function as separate units.
On 20 June 1948, a cargo ship, the Altalena, purchased and equipped in Europe by Irgun and its sympathizers and carrying 800 volunteers and large quantities of arms and ammunition, reached Israel's shores. Irgun demanded that 20 percent of the arms be allocated to its still independent units in Jerusalem, but the Israeli government ordered the surrender of all arms and of the ship. When the order was not complied with, government troops opened fire on the ship, which consequently went up in flames off Tel Aviv. On 1 September 1948, the remaining units of the Irgun disbanded and joined the IDF.
Historical Dictionary of Israel. Bernard Reich David H. Goldberg. Edited by Jon Woronoff..