Sandinista National Liberation Front

The FSLN emerged in the late 1950s and early 1960s from various opposition groups and youth and student organisations centred on the University of León and the National Autonomous University of Nicaragua. Inspired by the Cuban Revolution and the Algerian National Liberation Front, Carlos Fonseca, Silvio Mayorga, Tomás Borge and others founded it in 1961 as the National Liberation Front (FLN). On the founding date, the Spanish-language source gives 23 July 1961 in its introduction, but both sources say that the claim that it was founded at a meeting in Tegucigalpa on 19 July 1961 has no documentary support and first surfaced after the revolutionary victory of 1979. According to the Spanish-language source the name "Sandinista" was adopted on 23 July 1962 and came into use from 1963. No programmatic document was published until 1969.

After its defeat at Pancasán in 1967, the FSLN adopted the "Prolonged Popular War" (GPP) strategy of building a base in the rural mountains. In December 1974 an FSLN-affiliated guerrilla group took leading officials hostage at a party in the Managua suburb of Los Robles, winning a ransom of US$2 million and the broadcast of its communiqué, and over the next year secured the release of 14 prisoners, among them Daniel Ortega. The Somoza government imposed a state of siege in 1975, and Fonseca was killed after an ambush in 1976. From 1975 the FSLN split into the GPP, Jaime Wheelock's Proletarian Tendency and the Insurrectional Tendency (Terceristas) led by Daniel and Humberto Ortega and others. The Terceristas favoured temporary alliances with non-communists and in October 1977 allied with the Group of Twelve, made up of professionals, business leaders and clergymen.

The assassination in January 1978 of Pedro Joaquín Chamorro, editor of the opposition newspaper La Prensa, set off riots and a general strike. In August Tercerista commandos led by Edén Pastora seized the national congress with nearly 1,000 hostages, and Somoza paid a US$500,000 ransom and released 59 political prisoners, including Borge. The September insurrection was put down at a cost of several thousand lives but blurred the lines between the factions, and on 7 March 1979 the FSLN reunified under a nine-member National Directorate with three members from each tendency. A general strike was called on 4 June, a five-member Junta of National Reconstruction was formed in Costa Rica on 16 June, Somoza fled on 17 July and the FSLN army entered Managua on 19 July. The war left 30,000–50,000 dead and 150,000 in exile.

The FSLN government nationalised the property of the Somozas and their supporters and carried out land reform, a literacy campaign and an expansion of healthcare; according to the English-language source the literacy campaign taught half a million people in six months, bringing illiteracy down from over 50% to just under 12%. Violeta Barrios de Chamorro and Alfonso Robelo resigned from the junta in 1980, and according to the English-language source the FSLN took exclusive power in March 1981. Civil war began in 1981 with the Contras, among them the Nicaraguan Democratic Force (FDN), formed by the CIA with former members of Somoza's National Guard, and Pastora's Democratic Revolutionary Alliance (ARDE); the government declared a state of emergency in 1982, imposing censorship and bans on political assembly. In the 1984 election, boycotted by the main opposition coalition, the FSLN won 67% of the vote and 61 of 96 seats and Ortega was elected president, but the United States refused to recognise the election and imposed a total trade embargo in May 1985. The English-language source also records international criticism of human rights abuses, including mass executions and the oppression of indigenous peoples.

After the constitutional revision of 1987 and the Esquipulas II accord, Ortega won 41% in the election of 25 February 1990 against Violeta Chamorro's 55%, and the FSLN handed over power peacefully. In opposition the party went through the "piñata" controversy over confiscated property kept by its leaders and the breakaway of Sergio Ramírez's Sandinista Renovation Movement (MRS), and lost the presidential elections of 1996 and 2001. Ortega was elected president with 38% in 2006, and in 2009 the Supreme Court, with a majority of Sandinista judges, overturned presidential term limits. Ortega and the FSLN were re-elected in 2011, 2016 and 2021, in elections denounced by international observers. Many people died in the suppression of the 2018 protests, and on 30 January 2019 the FSLN was expelled from the Socialist International over human rights violations.