The Irgun (ארגון; full title: הארגון הצבאי הלאומי בארץ ישראל , lit. "The National Military Organization in the Land of Israel"), or Etzel (אצ"ל), was a Zionist paramilitary organization that operated in Mandate Palestine and then Israel between 1931 and 1948. It was an offshoot of the older and larger Jewish paramilitary organization Haganah (Hebrew: הגנה, Defence). The Irgun has been viewed as a terrorist organization or organization which carried out terrorist acts.
The Irgun policy was based on what was then called Revisionist Zionism founded by Ze'ev Jabotinsky. According to Howard Sachar, "The policy of the new organization was based squarely on Jabotinsky's teachings: every Jew had the right to enter Palestine; only active retaliation would deter the Arabs; only Jewish armed force would ensure the Jewish state".
Two of the operations for which the Irgun is best known are the bombing of the King David Hotel in Jerusalem on 22 July 1946 and the Deir Yassin massacre that killed at least 107 Palestinian Arabs, including women and children, carried out together with Lehi on 9 April 1948.
The organization committed acts of terrorism against the British, whom it regarded as illegal occupiers, and against Arabs. In particular the Irgun was described as a terrorist organization by the United Nations, British, and United States governments; in media such as The New York Times newspaper; as well as by the Anglo-American Committee of Inquiry, the 1946 Zionist Congress and the Jewish Agency. However, academics such as Bruce Hoffman and Max Abrahms have written that the Irgun went to considerable lengths to avoid harming civilians, such as issuing pre-attack warnings; according to Hoffman, Irgun leadership urged "targeting the physical manifestations of British rule while avoiding the deliberate infliction of bloodshed." Albert Einstein, in a letter to The New York Times in 1948, compared Irgun and its successor Herut party to "Nazi and Fascist parties" and described it as a "terrorist, right wing, chauvinist organization".