[1] He came from a humble family of peasants, his father being the Dominican Carlos Sablón Mañach and his mother the Cuban jiguanisera María Moreno.

Rabí took up arms against the Spanish colonial authorities in the Las Tunas region, remaining subordinate under the orders of General Donato Mármol.

On April 26, 1875, Rabí was one of the officers of the Cuban Liberation Army who supported the Sedition of Lagunas de Varona, led by Major General Vicente García González.

On February 10, 1878, the Zanjón Pact was signed between the Spanish colonial authorities and several senior Cuban officials, which ended the war without recognizing the independence of Cuba.

Rabí was among the group of oriental officers who met with Major General Antonio Maceo , on March 8, 1878, to decide the continuation of the war, which was unanimously approved.

After this protest, Rabí was promoted to Colonel and fought under the orders of Generals Manuel de Jesús Calvar and Guillermón Moncada, but the war was already lost and in a few months it ended irretrievably.

[2] Later, Rabí joined the Cuban Revolutionary Party, headed by José Martí, which unified all the people who wanted the independence of Cuba and Puerto Rico.

In the final months of 1895, he assumed the interim command of the Second Corps of the Cuban Liberation Army, replacing Major General Bartolomé Masó.

In this context, General Rabí refused to hold public office until the occupation was ended and the independent Republic was established , which finally happened on May 20, 1902.