The French Indo-China War of 1946-54 was one of the longest and bloodiest conflicts of the twentieth century. Dien Bien Phu became the site of the decisive battle of the French Indo-China War. Indeed, the French defeat at Dien Bien Phu set the stage for America's own military involvement in Viet-Nam a decade later. Yet despite its historic importance, there is still uncertainty about why the French chose to fight in a location that, in hindsight, involved such risks. In The Undetected Enemy, John Nordell examines that question by telling the full story of the strategic, tactical, logistical, and intelligence considerations that underlay the French decision. This book also gives close attention to the reaction of the Eisenhower administration to the French seizure of Dien Bien Phu, an important part of the story that, until now, has been overlooked. Using war memoirs, press coverage, and archived documents only recently declassified, the author weaves a compelling narrative of rapidly unfolding developments in Dien Bien Phu, Hanoi, Saigon, and Washington, D.C.