 By this point in Guevara 's life , he deemed that U.S.-controlled conglomerates installed and supported repressive regimes around the world . In this vein , he considered Batista a " U.S. puppet whose strings needed cutting " . Although he planned to be the group 's combat medic , Guevara participated in the military training with the members of the Movement . The key portion of training involved learning hit and run tactics of guerrilla warfare . Guevara and the others underwent arduous 15 @-@ hour marches over mountains , across rivers , and through the dense undergrowth , learning and perfecting the procedures of ambush and quick retreat . From the start Guevara was Alberto Bayo 's " prize student " among those in training , scoring the highest on all of the tests given . At the end of the course , he was called " the best guerrilla of them all " by their instructor , General Bayo . 
