On October 26th, 1959, the leader of the Revolution Fidel Castro announced the creation of the National Revolutionary Militias and military preparation began among the population.

Imperialism did all it could to stop Cuba from strengthening militarily and in March of 1960 Washington provoked the explosion of the French vessel La Coubre in Havana, while unloading weapons purchased in Belgium.

After the creation of the militias, the country carried out an enormous feat in the defense sector. Over 80 combat battalions were organized, prepared and armed with over 80 000 militias; 116 anti-aerial and land artillery batteries, equivalent to 696 pieces with its complements in addition to two heavy weapon battalions: the Rebel Army and the Police.

 
They also received and assimilated the armored techniques, enough to make up several companies of the legendary T-34 tanks, SAU-100 self propulsion cannons and the well known Stalin 2, all operated by members of the Rebel Army.

Tremendous efforts were made regarding the training of future officials.

In a short period the first 55 officials graduated in the first preparation of the cadet school; another course was carried out in the School of Responsible Militias, in which 536 new officials graduated and at the moment of the mercenary aggression, the second graduation was about to conclude with over 800 students.

 
This effort was carried out amidst constant military mobilizations; in hard and direct confrontation with the internal counterrevolution and the constant hostility from abroad.

 
Between September 1960 and early April 1961 Operation Limpia del Escambray
in its first stage was carried out which began the struggle against thousands of bandits in the mountains which were financed and organized by the CIA.

During that period the first military mobilization was carried out in the country, between the end of December 1960 and January 20th 1961 on the occasion of the new US administration.