restored with Israeli withdrawal. The All-Palestine Government was completely abandoned by Egypt in 1959 and was officially merged into the United Arab Republic, to the detriment of the Palestinian national movement. Gaza Strip then was put under the authority of the Egyptian military administrator, making it a de facto military occupation. In 1964, however, a new organization, the Palestine Liberation Organization (PLO), was established by Yasser Arafat. It immediately won the support of most Arab League governments and was granted a seat in the Arab League. The 1967 Six-Day War exerted a significant effect upon Palestinian nationalism, as Israel gained military control of the West Bank from Jordan and the Gaza Strip from Egypt. Consequently, the PLO was unable to establish any control on the ground and established its headquarters in Jordan, home to hundreds of thousands of Palestinians, and supported the Jordanian army during the War of Attrition, which included the Battle of Karameh. However, the Palestinian base in Jordan collapsed with the Jordanian–Palestinian civil war in 1970. The PLO defeat by the Jordanians caused most of the Palestinian militants to relocate to South Lebanon, where they soon took over large areas, creating the so-called "Fatahland". Palestinian insurgency in South Lebanon peaked in the early 1970s, as Lebanon was used as a base to launch attacks on northern Israel and airplane hijacking campaigns worldwide, which drew Israeli retaliation. During the Lebanese Civil War, Palestinian militants continued to launch attacks against Israel while also battling opponents within Lebanon. In 1978, the Coastal Road massacre led to the Israeli full-scale invasion known as Operation Litani. Israeli forces, however, quickly withdrew from Lebanon, and the attacks against Israel resumed. In 1982, following an assassination attempt on one of its diplomats by Palestinians, the Israeli government decided to take sides in the Lebanese Civil War and the 1982 Lebanon War commenced. The initial results for Israel were successful. Most Palestinian militants were defeated within several weeks, Beirut was captured, and the PLO headquarters were evacuated to Tunisia in June by Yasser Arafat's decision. The first Palestinian uprising began in 1987 as a response to escalating attacks and the endless occupation. By the early 1990s, international efforts to settle the conflict had begun, in light of the success of the Egyptian–Israeli peace treaty of 1982. Eventually, the Israeli–Palestinian peace process led to the Oslo Accords of 1993, allowing the PLO to relocate from Tunisia