The offensive was designed to crush Fidel Castro's revolutionary army, which had been growing in strength in the area of the Sierra Maestra mountains since their arrival in Cuba on board the Granma yacht in December 1956.

Throughout 1957, Fidel Castro's small band of revolutionaries operated out of a mountain base, staging hit and run attacks on the government of Batista.

The attitude of Batista changed in the Spring of 1958 as Castro started to gain international recognition and he called for a General Strike.

Batista decided to destroy Castro's small army, so in May 1958, General Eulogio Cantillo was given the mission.

Batista refused to allocate so many forces to the attack, instead Cantillo was given just 14 battalions (12,000 men)[citation needed], of which 7,000[citation needed] were new recruits with little training and little incentive to actually fight (in actual battle, the new recruits would rarely fight and often did nothing).

Castro's troops knew the terrain well, and they set up mine fields and built defensive positions along the major routes through which they expected the army to attack.

He also had the support of local peasants, who assisted in the transmission of information on Cantillo's troops and risked their lives to hide rebel supplies.

Castro's troops, for the first time, were caught by the trap and more than 70 were killed in the first two days of fighting, including a senior rebel leader, René Ramos Latour.