The Jewish Resistance Movement
At the end of World War II, when it became clear that the British government had no intention of altering its Anti-Zionist policy, the yishuv organized the Jewish Resistance Movement, which was run by the Haganah in cooperation with Etzel and Lehi.
The movement carried out its first operation on October 1945, when a Palmach unit attacked the Atlit internment camp and liberated the 208 illegal immigrants held there. In November 1945, the Movement showed its strength by launching a major attack on railroads all over the country and sinking several coastal patrol launches. In the following months, the Movement carried out attacks upon British police posts, coast guard stations, radar installations and air-fields.
In June 1946, the Jewish Resistance Movement blew up the bridges linking Palestine with neighboring states. The British authorities reacted to this attack on June 29, 1946 (Black Saturday), by arresting the members of the Jewish Agency Executive. Military forces conducted searches for arms caches in the settlements and thousands of people were arrested. The Jewish Agency ordered a halt in the armed operations against the British, but Etzel and Lehi refused to comply. In July 1946, Etzel blew up the central government offices at the King David Hotel in Jerusalem. 80 people were killed government officials and civilians, Britons, Jews and Arabs. After this operation, condemned outright by the Jewish Agency and by the Haganah, the Jewish Resistance Movement ceased to exist.
Source: Joint Authority for Jewish Zionist Education