The United States was first introduced to the vexations of large-scale guerrilla warfare forty years ago in the mountain jungles of Nicaragua. There for the first time Americans were confronted by an elusive partisan leader of a type to become bitterly familiar not only in the Caribbean but in Southeast Asia, a man who pioneered techniques of warfare when Che Guevara and Fidel Castro were in rompers and Mao Tse-tung was an obscure revolutionary. “Mr. Coolidge’s War,” the affair has been called. More formally, it was the American intervention in Nicaragua of 1927-28—and though it was not one of the thunderclaps of history, its significance is evident.