The proximate trigger for the November 13 revolt, however, was Ydígoras' decision to allow the United States to bring soldiers into Guatemala to train for the Bay of Pigs Invasion of Cuba.

The rebel officers were concerned about loss of national sovereignty as the U.S. established a secret air strip and training camp at Retalhuleu to prepare for the invasion of Cuba.

The attack sparked sympathetic strikes and university student walkouts throughout the country, to which the Ydígoras regime responded with a violent crackdown.

The three "frentes" (each comprising no more than 500 combatants) were led by former members of the 1960 army revolt, who had previously been trained in counterinsurgency warfare by the United States.

A 1968 CIA report stated: "With some assistance from Cuba, the small band, under the leadership of Marco Antonio Yon Sosa, engaged in sporadic terrorist acts, including harassment of communications lines, buses, and railroad tracks, pillaging of military supply points and plantations for money and arms, assassination of army collaborators, and attacks on commercial and official installations.

Victims of the repression included the Maya indigenous people, activists, suspected government opponents, returning refugees, critical academics, students, left-leaning politicians, trade unionists, religious workers, journalists, and street children on a scale that has been termed the Guatemalan genocide.