The first part of the conflict pitted the Yishuv's forces against those of the Palestinian's Arab Higher Committee. The civil war began with three days of strikes on November 30, 1947. It then changed into a guerrilla campaign against Jewish supply trucks. In January 1948, the Arab Liberation Army entered Palestine. This stiff resistance caused the Israelis to adapt their plan and to introduce Plan Dalet. On April 5th, the Haganah launched Operation Nahshon, a fifteen-day operation to secure routes to Jerusalem by seizing hills along the main roads. After the success of Operation Nahshon and smaller Jewish offensives, Palestinian resistance began to fall apart.