Lying due north of Australia, New Guinea is among the world’s largest islands. In 1942, when World War II exploded onto its shores, it was an inhospitable, cursorily mapped, disease-ridden land of dense jungle, towering mountain peaks, deep valleys, and fetid swamps. Coveted by the Japanese for its strategic position, New Guinea became the site of one of the South Pacific’s most savage campaigns. Despite their lack of jungle training,...