Former Cuban President and revolutionary leader Fidel Castro died on Saturday after battling a long illness.

Both the leaders shared a mutual admiration of the other, while Guevara looked up to Castro as man with a “Razor-sharp” mind and commitment towards socialism, Castro saw an honest, hardworking and self-sacrificing man in Guevara.

“If we wish to express what we want the men of future generations to be, we must say: Let them be like Che! If we wish to say how we want our children to be educated, we must say without hesitation: We want them to be educated in Che’s spirit! If we want the model of a man, who does not belong to our times but to the future, I say from the depths of my heart that such a model, without a single stain on his conduct, without a single stain on his action, is Che!” Castro had once said of Che.

The complexities of the relationship between the two have always been a topic of discussion, while many believe that they shard a great bond of friendship, t are also theories which suggest that Castro betrayed their friendship by not assisting Guevara during the end of his days.

Castro met Guevara during his travel to Mexico after serving a year of imprisonment for launching a failed attack on the Moncada Barracks in 1953 to overthrow Batista.

Fidel Castro, brother Raul Castro and Che Guevara then sailed to Cuba to rebel against the government.

After Guevara left Havana, a controversy began to rise as to whether the leader’s departure from the country was caused by a political or personal split between him and Fidel Castro.

In an article published in April, 2015, a Cuban journalist Alberto Müller claimed that Castro betrayed Guevara during the end of his days after he left Cuba.

The journalist said that t was a guerrilla unit in Havana ready to deploy and rescue Guevara, but “Fidel never authorized the mission,” abandoning Guevara to his fate.