Rebel victory National Liberation Army Ulatista Forces Caribbean Legion Supported by: The Costa Rican Civil War took place from 12 March to 24 April 1948.

The uprising was resisted by the small, ill-equipped Costa Rican army and, more significantly, by the militias of the Communist People's Vanguard Party, which was part of the governing coalition in the Legislative Assembly and had voted to annul the presidential elections.

After the war, Figueres toppled the army and ruled the country for 18 months as head of a provisional government junta, which oversaw the election of a Constitutional Assembly in December.

The Costa Rican communist movement, organized in the Popular Vanguard Party led by congressman Manuel Mora, was allied to Picado's government and contributed to the unrest by deploying its militia against the opposition.

[citation needed] Disgust with the government's violent reprisals against the opposition led to the Huelga de Brazos Caídos, a strike that stalled commerce in Costa Rica for seven days.

[2] Calderón returned as the ruling party's candidate for the election of 1948 and there were widespread fears that the government would intervene to ensure his triumph against his main opponent, journalist Otilio Ulate.

José Figueres, a Costa Rican businessman, had been forced into exile in Mexico on April 12, 1942, after he strongly criticized the Calderón regime during a radio broadcast.

U.S. officials followed the Legion's activities with concern, especially after Figueres carried out terrorist attacks inside Costa Rica during 1945 and 1946 that were meant to incite a general strike.

[8][6] On the day that the government annulled the elections, police surrounded the home of Dr. Carlos Luis Valverde, the acting campaign manager for Union National, where Ulate was and Figueres had been only moments before.

[5][9] The annulment of the election results in 1948 and the killing of Valverde on the same day seemed to give Figueres the evidence that he needed that the government had no intention of peacefully accepting the popular will, thus justifying a violent insurrection.

Figueres also contended against the communist militias commanded by congressman Carlos Luis Fallas and against Nicaraguan soldiers who had been sent by Somoza to help the government retain power.

On April 19, Picado and Father Benjamín Núñez, an eminent labor leader within Costa Rica, signed the so-called Pact of the Mexican Embassy, ending the armed uprising.