Haganah (Hebrew: הַהֲגָנָה ha-Haganah, lit. 'The Defense') was the main Zionist paramilitary organization that operated for the Yishuv in the British Mandate for Palestine. It was founded in 1920 to defend the Yishuv's presence in the region, and was formally disbanded in 1948, when it became the core force integrated into the Israel Defense Forces shortly after the Israeli Declaration of Independence.
Formed out of previous existing militias, Haganah's original purpose was to defend Jewish settlements against Arab attacks; this was the case during the 1921 Jaffa riots, the 1929 Palestine riots, the 1936 Jaffa riots, and the 1936–1939 Arab revolt in Palestine, among others. The paramilitary was under the control of the Jewish Agency, the official governmental body in charge of Palestine's Jewish community during the British era. Until the end of World War II, Haganah's activities were moderate, in accordance with the strategic policy of havlagah (lit. 'self-restraint'), which caused the breakaway of the more radical paramilitaries: Irgun and Lehi. Haganah militants received clandestine military support from Poland and sought cooperation with the United Kingdom in the event of an Axis-led invasion of Palestine through North Africa, prompting the creation of the Palmach, their elite fighting force, in 1941.