Ernesto "Che" Guevara was one of the greatest exemplars of the revolutionary 1960s, a man whose heroic adventures were essential to the success of the Cuban Revolution and whose legend fired the imaginations of a whole generation. In 1965, amid worldwide conjecture, Guevara left Cuba, where he was a minister in Fidel Castro's postrevolutionary government, and traveled incognito to the heart of Africa. People's hero Patrice Lumumba had recently been...