Oppositional rebels, known as Contras, formed in 1981 to resist the Sandinista's Junta and received support from the American Central Intelligence Agency.
The FSLN lost elections in 1990 to Violeta Barrios de Chamorro, after revising the constitution in 1987 and after years of resisting the United States-supported Contras, but retained a minority of seats in the legislature.
Urban insurrection was the crucial element because the FSLN could never hope to achieve simple superiority in men and firepower over the National Guard.
On June 16, the formation of a provisional Nicaraguan government in exile, consisting of a five-member Junta of National Reconstruction, was announced and organized in Costa Rica.
While initially seeking to remain in power to serve out Somoza's presidential term, Urcuyo seceded his position to the junta and fled to Guatemala two days later.
The five-member junta entered the Nicaraguan capital the next day and assumed power, reiterating its pledge to work for political pluralism, a mixed economic system, and a nonaligned foreign policy.
[6] The Sandinistas inherited a country in ruins with a debt of 1.6 billion dollars (US), an estimated 50,000 war dead, 600,000 homeless, and a devastated economic infrastructure.
[8] As Nicaragua's government collapsed and the National Guard commanders escaped with Somoza, the U.S. first promised and then denied them exile in Miami.
On July 19, 1979, a new government was proclaimed under a provisional junta headed by 35-year-old Daniel Ortega and including Violeta Chamorro, Pedro's widow.
Lake Managua was considered dead because of decades of pesticide runoff, toxic chemical pollution from lakeside factories, and untreated sewage.
One prominent Contra commander, however, was ex-Sandinista hero Edén Pastora, aka "Commadante Zero," who rejected the Leninist orientation of his fellow comandantes.
The United States quickly suspended aid to Nicaragua and expanded the supply of arms and training to the Contra in neighbouring Honduras, as well as allied groups based to the south in Costa Rica.
Under the new "Law for the Maintenance of Order and Public Security" the "Tribunales Populares Anti-Somozistas" allowed for the indefinite holding of suspected counter-revolutionaries without trial.
Reagan's officials attempted to illegally supply them out of the proceeds of arms sales to Iran and third party donations, triggering the Iran-Contra Affair of 1986-87.
[12] The primary opposition candidate was the U.S.-backed Arturo Cruz, who succumbed to pressure from the United States government[13] not to take part in the 1984 elections; later US officials were quoted as saying, "the (Reagan) Administration never contemplated letting Cruz stay in the race, because then the Sandinistas could justifiably claim that the elections were legitimate...Other Administration officials vehemently denied this contention.
[17] Ortega was overwhelmingly elected president in 1984, but the long years of war had decimated Nicaragua's economy and widespread poverty ensued.
(William I Robinson, op cit)[21] The Library of Congress Country Studies on Nicaragua states: Despite limited resources and poor organization, the UNO coalition under Violeta Chamorro directed a campaign centered around the failing economy and promises of peace.