Operation Barak was launched on 9 May 1948, mainly by the Haganah's Giv'ati Brigade, to "clear" the southern and western ends of its zone of control before 15 May. It targeted the villages south and west of Ramla. The Palmach's Negev Brigade also took part; it moved toward Ramla from the south, while the Giv'ati Brigade approached Ramla from the north. The operational plan was that the Giv'ati Brigade would fan out from its headquarters in the settlement of Rechovot, west of Ramla. Its objective, stated in the operational orders quoted by Israeli historian Benny Morris, was to "deny the enemy a base ... creating general panic and breaking his morale ... " Morris reports that one of the declared aims was to drive out a large number of Palestinians from the villages in the occupied area.
The Giv'ati Brigade expanded the area under its control in this operation and "cleared" the coastal area west of Ramla and Lydda, in accordance with Plan Dalet. The plan's guidelines to the commander of the brigade, Shim'on Avidan, said, in part: "You will determine alone, in consultation with your Arab affairs advisers and Intelligence Service officers, [which] villages in your zone should be occupied, cleaned up or destroyed." In keeping with the Giv'ati Brigade's practice during this operation, any villagers who remained in a village after it had been occupied were subject to expulsion.
As British forces withdrew from Palestine, on 15 May 1948, the Haganah launched the second stage of Operation Barak in the south of the country. By the end of May the two brigades occupied more than thirty villages and had driven out tens of thousands of people.
Morris, Benny. The Birth of the Palestinian Refugee Problem 1947-1949. Cambridge: Cambridge University Press, 1978, pp. 125-27.