The Acre Prison break was an operation undertaken by the Irgun on May 4, 1947, in the British Mandate of Palestine, in which its men broke through the walls of Acre prison and freed 28 incarcerated Irgun and Lehi members.
At the time of the British Mandate the citadel in the old city of Acre was used as a prison. In total, the prison contained 700 Arab prisoners and 90 Jewish prisoners, the latter mainly members of the Jewish underground groups Haganah, Lehi, and Irgun, who were captured by the British. One of those prisoners was Eitan Livni (father of Tzipi Livni), the Irgun operations officer.
On April 19, 1947, four Irgun members, Dov Gruner, Yehiel Dresner, Mordechai Alkahi, and Eliezer Kashani, who were captured by the British 6th Airborne Division, were hanged in Acre Prison to become the Irgun's first postwar 'martyrs'. At his trial, Dov Gruner declared the British Army and Administration to be 'criminal organizations'.
The Lehi and Irgun prisoners mulled an escape but concluded that would be impossible without outside assistance. They therefore contacted Irgun headquarters with a plan. Dov Cohen, AKA "Shimshon", was selected to lead the operation.
The break-out was originally planned for April, but was eventually rescheduled for Sunday, May 4, 1947, at 4 p.m., the day the United Nations General Assembly convened to discuss the Palestine issue.
The Irgun High Command selected 41 prisoners for escape: 30 Irgun and 11 Lehi, as that was the available number of spots available at safe houses. The Irgun High Command, and Eitan Livni, an imprisoned Irgun member, extensively planned the break and escape route.