Spies for Nimitz: Joint Military Intelligence in the Pacific War

Article excerpt

Moore, Jeffrey M. Spies for Nimitz: Joint Military Intelligence in the Pacific War. Annapolis, Md.: Naval Institute Press, 2004, 336pp. $29.95

Despite its title, this book is not about spies but about what is referred to in today's parlance as "intelligence preparation of the battlefield": a sustained process of research and analysis, based on all source collection efforts, that identifies important aspects of potential combat environments. Intelligence preparation of the battlefield provides planners and commanders with "combat intelligence"-about the terrain, weather conditions, enemy order of battle and dispositions-needed to conduct an upcoming operation. For instance, without knowledge of tidal conditions, currents, the composition and slope of a beach, or the location of underwater obstructions and mines, amphibious operations can be doomed to failure before they begin.

In this history of the performance of U.S. intelligence in the Pacific during World War II, Jeffrey Moore links the intelligence provided to planners by the Joint Intelligence Center Pacific Ocean Area (JICPOA) to the outcome of the major amphibious assaults against Japanese-occupied islands. Intelligence preparation of the battlefield, always important, was of great strategic significance in the "island hopping" campaign undertaken by the United States. Planners had to identify atolls or islets that were lightly defended by the Japanese yet possessed the anchorages, landing strips, and flat terrain that made them suitable as operating bases for the next stage in the campaign. When intelligence analysts provided accurate pictures of the battlefield, operations generally went smoothly and U.S. casualties were light. When they underestimated enemy strength, failed to warn the assault of strange topographic conditions, or failed to anticipate shifts in enemy strategy, the outcome was a grinding attritional battle that generated high losses.

American intelligence analysts and planners knew very little about the Marshall, Mariana, or Caroline Islands. Of course, many of the atolls and islets targeted in the American march across the Pacific were extraordinarily isolated and had been inhabited mostly by Polynesians before the war. More surprisingly, planners also knew little about American islands that had been seized by the Japanese in the immediate aftermath of Pearl Harbor. Guamanians who had left their home island when the Japanese invaded had to be consulted about topography, road networks, and tidal conditions to support plans for the assault on Guam. The U.S. Navy had supposedly been planning operations against Japan for years; it is hard to explain why so little effort had been made to gather basic information about the Pacific islands.

In assessing JICPOA's performance, Moore identifies a perplexing trend-that U.S. intelligence actually deteriorated as the war progressed. Intelligence performed relatively well against early targets (Kwajalein, Eniwetok, Tinian, and Guam), probably because these atolls were lightly defended by the Japanese and relatively few fortifications had to be identified in the planning of shore bombardment. …