The Lebanese Forces were established in 1976, initially as a joint military command for the Lebanese Front coalition. It grouped the military organizations of four predominant parties: the Kataeb party, the National Liberal Party's Numur, the Guardians of the Cedars and the Tanzim. Bashir Gemayel commanded the Lebanese Forces, in collaboration with the military leaders of the parties involved. In 1980 Bashir Gemayel launched an offensive against Dani Chamoun's Numur, terminating its military power.

Gemayel gained exclusive command of the Lebanese Forces and military control over Beirut's eastern sectors, as the military structures of the rest of the political groups were absorbed into its ranks. The Lebanese Forces grew into a formidable military structure benefiting from the support of Israel and the backing of other political powers. The Lebanese Forces in 1985, under Elie Hobeika and Samir Geagea, staged a coup to gain political governance independent from the Kataeb and Amin Gemayel's rule. This was followed by a second uprising in 1986, against Hobeika's accommodating relation with Syria, bringing Geagea to power.

Operating under the Palestinian Liberation Organization (PLO), the Palestinian resistance grouped a number of organizations with varied ideologies, each with its own leadership and military apparatus: Fatah, Popular Front for the Liberation of Palestine (PFLP), Democratic Front for the Liberation of Palestine (DFLP), Arab Liberation Front, as-Sa'iqa, PFLP - General Command, and the Palestine Liberation Army, the official military arm of the PLO.

In 1969 an agreement signed in Cairo between the Lebanese army and the PLO officially permitted Palestinian resistance while constraining it to Lebanon's southern border. Following the expulsion of the PLO from Jordan in 1970, the organization moved its headquarters to Lebanon. South Lebanon became an important base for military operations on the border with Israel. The resistance organizations benefited from the political support of left-wing and Arab nationalist parties and held Lebanese partisans among their ranks.

The PLO was a major actor in the war as it supported the combined forces of the LNM on many levels, lending financial support, military resources and training. Military factions of the PLO participated - unofficially - in the war fronts. However, Syria's intervention in Lebanon in 1976 and its pronounced discord with the PLO produced a different political set-up that rendered the PLO openly active in the armed conflict. Following the 1982 Israeli invasion, the PLO forces were evacuated from Beirut under the supervision of multinational forces.

Following the Israeli invasion, the Lebanese National Resistance Front was created on 16 September 1982 at the initiative of the Lebanese Communist Party and the Organization of Communist Action. The front formalized the resistance activities of those parties, as well as the Syrian Social Nationalist Party and other members of the Front of Patriotic and National Parties. The front was forced to halt its resistance operations as of 1987 with the rise of Hizbullah's Islamic Resistance.

Founded in 1949 and led by Kamal Jumblatt, a descendant of a Druze feudal family of the Shouf Mountains. Jumblatt played a key role in civil war politics, since he presided over the National Movement. Jumblatt contested Syria's intervention in 1976; he denounced its plan to prevent an imminent victory of the LNM and weaken the Palestinian resistance. Jumblatt was assassinated on 16 March 1977. In the same year Walid, Kamal Jumblatt's son, who succeeded his father in leadership of the party and the LNM, issued a common statement with the pro-Syrian Baath party and began to reconcile the PSP with the Patriotic Front and Syria. Despite secular beginnings and progressive programmes, the PSP came to represent a continuation of the Jumblatt family's traditional leadership over the Druze sect when Walid Jumblatt assumed leadership. The party's Druze identity got further pronounced as it engaged in Druze-Christian intercommunitarian violence during the 1982-4 mountain battles with the Lebanese Forces.

Lebanese Communist Party (LCP)

It was founded in 1924 as the Communist Party of Syria and Lebanon, remaining so until 1944 when independent parties were established in each country. Its membership is multi-confessional; it grouped a large body of intellectuals and workers among its ranks. The LCP featured significantly in the National Movement and participated actively in the war front from 1975. In 1982 it formed the Lebanese National Resistance Front with other parties, and led major military operations against the Israeli occupation. The party suffered from the assassination of some of its prominent members throughout the course of the war.

Organization of Communist Action in Lebanon (OCA)

Founded in 1970 as a union between two radical-left movements, the OCA was an independent organization that adopted Marxist-Leninist thought. It represented the new left with an overwhelmingly youth multi-confessional membership that was inspired by the revolutionary struggles and protest movements of the late 1960s. It played an important role in the war politics, as its leader Mohsen Ibrahim was the executive secretary of the National Movement. Its military forces actively engaged on the war front and particularly in joined operations with the Palestinian forces in the south. The organization partook in the formation of the Lebanese National Resistance Front.

Founded in 1932 by Antun Saadeh, the SSNP held the objective of resuscitating historic Greater Syria as a unified social and geographic national entity. The party grew considerably and had multi-sectarian membership. Saadeh was executed by the Lebanese state in 1949, accused of an attempted coup d'état. The SSNP fought on many fronts alongside the LNM and the PLO in 1975 and 1976. With Syria's intervention in 1976 and rising tensions between LNM-PLO and Syria, the party's internal political divisions were aggravated. It suffered defections, forming a separate faction aligned with Syria. The party actively participated from 1982 in the National Resistance Front and undertook many military operations against Israeli occupation in Beirut and South Lebanon. The SSNP's resistance endeavours were halted in 1987 with the ascendancy of the Islamic Resistance coupled with heightened internal discords in the party leadership and politics of alliance with Syria.

Independent Nasserite Movement - Murabitun (INM):
Formed in 1958 and led by Ibrahim Koleilat, the Murabitun embraced the pan-Arab nationalist and socialist projects of the Egyptian president Gamal Abd-el-Nasser and was a firm supporter of the Palestinian resistance. Al-Murabitun, the movement's military wing, played a major part during the civil war, fighting among the combined forces of the LNM. Most of its members were Sunni Muslim. In 1985 the Progressive Socialist Party and Amal joined forces to suppress the Murabitun and forced Koleilat into exile.

Arab Socialist Union:
Its formation in Lebanon dates back to the early 1970s as a Nasserist movement tied to the Arab Socialist Union in Egypt. In 1975 the movement split into two factions, both of which were active in the LNM.

Other smaller Nasserist movements were equally active in Lebanon and partook in the civil war: the Popular Nasserist Organization, based in Saida, led by Maarouf Saad and subsequently his two sons; and the Union of Toiling Peoples' Forces, based in west Beirut and led by Kamal Shatila.

Amal means 'Hope' and is the acronym for Afwaj al-Muqawama al-Lubnaniya (Lebanese Resistance Detachments), a movement established in 1975 by the Shi'ite cleric Imam Mussa al-Sadr, as the military arm of the Movement of the Disinherited, which he had founded a year earlier. Al-Sadr advocated socio-political reform and called for social equality for the deprived communities in underdeveloped areas in South Lebanon and the Bekaa. Although officially secular, Amal's membership is overwhelmingly Shi'ite. The movement has worked to mobilize the Shi'ite community around an articulated struggle of confession and class. Al-Sadr disappeared in 1978 during a visit to Libya; he was succeeded by Hussein el-Husseini until Nabih Berri took charge in 1980. Amal did not participate in the 1975-6 fighting; it adhered to the Patriotic Front and endorsed Syria's intervention in 1976. While it officially supports the Palestinian cause in its liberation struggle, Amal repeatedly clashed with the PLO forces in Beirut and southern Lebanon during the 1980s; yet, despite its continuous clashes in west Beirut with other parties (Murabitun, PSP and Hizbullah), Amal also took part in the resistance against Israel in South Lebanon.

Formed in 1982 at the initiative of a group of Shi'ite clerics who split from the Amal movement, drawn by the Islamic revolution in Iran, and who adhered to the jurisprudence of Khomeini (Wali al-Faqih). Hizbullah ('party of God') received Iranian support, which helped establish the party's military infrastructure and institutional development. Hizbullah was officially proclaimed in 1984; it announced the party's active participation in the resistance to Israeli occupation through its military arm, the Islamic Resistance. Hizbullah conceive of their military role as a 'defensive jihad' against oppressors of the Umma (Muslim community), taking as a model the martyrdom of Imam Hussein in Karbala (ad 680). The Shi'ite narrative of the Karbala event, commemorated annually through the holiday of Ashura, has marked and informed a Shi'ite revolutionary discourse in Iran and largely inspired the politico-religious ideology of Hizbullah. As the party's growth posed a threat to Israel, its main leaders have repeatedly been targets of Israeli assassinations, among them the founding member Sheikh Ragheb Harb (1984) and the party's secretary-general Abbas Mussawi (1991).