For some time Arab villages east of Jaffa had been threatening the road to Jerusalem and created a wedge between the Jewish areas to the north-east and south-east of Tel Aviv. Arab attacks were being mounted constantly on the outlying areas of Tel Aviv, and snipers from Jaffa's high buildings covered the main thoroughfares inside Tel Aviv, so that innocent passers-by could be picked off. In the Tel Aviv area, the Alexandroni Brigade commanded by Dan Even along with forces from the Kiryati and Givati brigades launched Operation Hamez (Leaven) on the eve of Passover. The aim of the operation was to capture the Arab villages east of Jaffa: Hiriya, Sakiya, Salame, and Yazur. The Jews did not originally plan to capture Jaffa, rather their aim was to use an indirect approach to encircle the number of Arab villages east of it which endangered the road to Jerusalem. As long as the threat of the Arab Armies was minimal, the Haganah forces refrained from attacking Jaffa. The encirclement of Jaffa was completed on April 29, and most of its 70,000 Arabs inhabitants fled. Its final surrender came on May 13, when the British troops left. On May 14th, the Beit Dajon police station was captured, thus opening the road to Ramlah and the South.
Source: Israel Defense Forces