The Lebanese Civil War (13 April 1975 – 13 October 1990, Arabic: الحرب الأهلية اللبنانية, romanized: Al-Ḥarb al-Ahliyyah al-Libnāniyyah) was a multifaceted civil war in Lebanon resulting in an estimated 120,000 fatalities. There was also an exodus of almost one million people from Lebanon as a result of the war.Lebanon is multi-sectarian, with Sunni Muslims and Christians being the majorities in the coastal cities, Shia Muslims being mainly based in the south and the Beqaa Valley to the east, and with the mountain populations being mostly Druze and Christian. The government of Lebanon had been run under a significant influence of the elites among the Maronite Christians. The link between politics and religion had been reinforced under the mandate of the French colonial powers from 1920 to 1943, and the parliamentary structure favored a leading position for its Christian population. However, the country had a large Muslim population and many pan-Arabist and left-wing groups opposed the pro-western government. The establishment of the state of Israel and the displacement of a hundred thousand Palestinian refugees to Lebanon during the 1948 and 1967 exoduses contributed to shifting the demographic balance in favor of the Muslim population. The Cold War had a powerful disintegrative effect on Lebanon, which was closely linked to the polarization that preceded the 1958 political crisis, since Maronites sided with the West while leftist and pan-Arab groups sided with Soviet-aligned Arab countries.Fighting between Maronite and Palestinian forces (mainly from the Palestine Liberation Organization) began in 1975, then Leftist, pan-Arabist and Muslim Lebanese groups formed an alliance with the Palestinians. During the course of the fighting, alliances shifted rapidly and unpredictably. Furthermore, foreign powers, such as Israel and Syria, became involved in the war and fought alongside different factions. Peacekeeping forces, such as the Multinational Force in Lebanon and the United Nations Interim Force in Lebanon, were also stationed in Lebanon.

The 1989 Taif Agreement marked the beginning of the end of the fighting. In January 1989, a committee appointed by the Arab League began to formulate solutions to the conflict. In March 1991, parliament passed an amnesty law that pardoned all political crimes prior to its enactment. In May 1991, the militias were dissolved, with the exception of Hezbollah, while the Lebanese Armed Forces began to slowly rebuild as Lebanon's only major non-sectarian institution. Religious tensions between Sunnis and Shias remained after the war.