Operation Bi'ur Hametz was part of the larger Operation Misparayim ("Scissors"), which was designed to cut the Arab section of Haifa in two. Bi'ur Hametz began on 22 April, two days after the fall of Haifa, with attacks on Balad al-Shaykh, some 10 km northwest of Khirbat al-Mansura. It continued for at least another three days, during which Haganah units (primarily Carmeli Brigade units) were deployed in the last week of April 1948 to occupy Haifa's hinterland and tighten their hold on the city. In a report filed at the end of April, British army officers said they thought it "likely that the Haganah will continue mortaring and shelling around Haifa to create an evacuation of the [Arab] population."
Israeli Ministry of Defense. Toldot Milchemet ha-Qomemiyyut [The History of the War of Independence]. Tel Aviv: Marakhot, 1959, p. 252.
Morris, Benny. The Birth of the Palestinian Refugee Problem 1947-1949. Cambridge: Cambridge University Press, 1978, p. 75, 93-94.