Che in the Revolution
Che was an important player in the Cuban Revolution, perhaps second only to Fidel himself. Che was clever, dedicated, determined and tough. His asthma was a constant torture for him. He was promoted to comandante and given his own command. He saw to their training himself and indoctrinated his soldiers with communist beliefs. He was organized and he demanded discipline and hard work from his men. He occasionally allowed foreign journalists to visit his camps and write about the revolution. Che's column was very active, participating in several engagements with the Cuban army in 1957-1958.
In the summer of 1958, Batista decided to try and stomp out the revolution once and for all. He sent large forces of soldiers into the mountains, seeking to round up and destroy the rebels once and for all. This strategy was a huge mistake, and it backfired badly. The rebels knew the mountains well and ran circles around the army. Many of the soldiers, demoralized, deserted or even switched sides. At the end of 1958, Castro decided it was time for the knockout punch, and he sent three columns, one of which was Che's, into the heart of the country.
Che was assigned to capture the strategic city of Santa Clara. On paper, it looked like suicide: there were some 2,500 federal troops there, with tanks and fortifications. Che himself only had some 300 ragged men, poorly armed and hungry. Morale was low among the soldiers, however, and the populace of Santa Clara mostly supported the rebels. Che arrived on December 28 and the fighting began: by December 31 the rebels controlled the police headquarters and the city but not the fortified barracks. The soldiers inside refused to fight or come out, and when Batista heard of Che's victory he decided the time had come to leave. Santa Clara was the largest single battle of the Cuban Revolution and the last straw for Batista.
After the Revolution
Che and the other rebels rode into Havana in triumph and began setting up a new government. Che, who had ordered the execution of several traitors during his days in the mountains, was assigned (along with Raúl) to round up, bring to trial and execute former Batista officials. Che organized hundreds of trials of Batista cronies, most of them in the army or police forces. Most of these trials ended in a conviction and execution. The international community was outraged, but Che didn't care: he was a true believer in the Revolution and in communism. He felt that an example needed to be made of those who had supported tyranny.
As one of the few men truly trusted by Fidel Castro, Che was kept very busy in post-Revolution Cuba. He was made head of the Ministry of Industry and head of the Cuban Bank. Che was restless, however, and he took long trips abroad as a sort of ambassador of the revolution to improve Cuba's international standing. During Che's time in governmental office, he oversaw the conversion of much of Cuba's economy to communism. He was instrumental in cultivating the relationship between the Soviet Union and Cuba, and had played a part in trying to bring Soviet missiles to Cuba. This, of course, caused the Cuban Missile Crisis.
In 1965, Che decided that he was not meant to be a government worker, even one in a high post. His calling was revolution, and he would go and spread it around the world. He disappeared from public life (leading to incorrect rumors about a strained relationship with Fidel) and began plans for bringing about revolutions in other nations. The communists believed that Africa was the weak link in the western capitalist/imperialist stranglehold on the world, so Che decided to head to the Congo to support a revolution there led by Laurent Désiré Kabila.
When Che had left, Fidel read a letter to all of Cuba in which Che declared his intention to spread revolution, fighting imperialism wherever he could find it. Despite Che's revolutionary credentials and idealism, the Congo venture was a total fiasco. Kabila proved unreliable, Che and the other Cubans failed to duplicate the conditions of the Cuban Revolution, and a massive mercenary force led by South African "Mad" Mike Hoare was sent to root them out. Che wanted to remain and die fighting as a martyr, but his Cuban companions convinced him to escape. All in all, Che was in Congo for about nine months and he considered it one of his greatest failures.