Uncovering Ways of War: U.S. Intelligence and Foreign Military Innovation, 1918-1941 (review)

Military effectiveness inevitably relies on understanding and, in the best of worlds, anticipating the way an enemy will fight. Hence, the role of intelligence in military preparations is a key issue and one that is often not well understood. Thomas Mahnken tackles a slice of this issue in his study of U.S. military and naval attachés inJapan, Germany, and Great Britain between World War I and World War II. Thisbook provides excellent case studies, telling us what these attachés actually didand how they contributed to U.S. preparations, and will be a great resource for future scholars. Although Mahnken's general claims about the lessons of these cases for intelligence and military preparations are less satisfactory, the cases alone are sufficient reason to read the book.

The conventional wisdom dismisses the contribution of U.S. intelligence to military preparations between the World Wars. By studying the role of attachés in Britain, Germany, and Japan, however, Mahnken demonstrates that intelligence did contribute more than is commonly understood, and he seeks to explain what led to better or worse intelligence among the cases. His general argument is rooted in the organizational and psychological bias models that have long dominated the literature on military innovation, and the patterns that he notes are not surprising. Good intelligence is most likely when innovations in existing weapons systems have been demonstrated on the battlefield and are under consideration by the country's own armed forces. Innovations in entirely new systems, which have not been demonstrated on the battlefield or have been rejected or overlooked by the country's own military, are more likely to be missed.

Mahnken challenges previous studies of U.S. interwar intelligence, arguing that despite the paucity of investment in intelligence the United States did a reasonable job figuring out what the enemy was up to, provided that U.S. agencies were tracking incremental innovations in established weapons systems that the U.S. military itself was considering for adoption. This would apply, for example, to Japanese amphibious warfare and German armored warfare. But the United States had a much harder time with innovations in new weapons systems that had not undergone battlefield testing, such as German missile technology, Japanese carrier aviation, and, to a lesser extent, Japanese surface warfare and German tactical aviation. Although it is probably true that the United States generates better intelligence when it is focusing on systems that it wants to adopt for its own armed forces, this is hardly shocking news—but neither is it the interesting part of Mahnken's study.

In chapters 2 to 5, Mahnken combs the archives as well as the secondary literature to tell the story of military attaché offices in each of the three countries in great detail. These fascinating cases present a more nuanced view of intelligence than his general argument captures and suggest a number of additional variables that may be important for ensuring good intelligence. For instance, the contacts maintained by attachés help determine the nature and volume of information the United States has at its disposal. In Japan the officers were junior—lieutenants or captains—and thus had contact only with low-ranking Japanese officers who were less knowledgeable about operational art and strategy. Similarly, in Germany U.S. officers had a range of sources within the War Ministry and Wehrmacht but fewer contacts (and poorer information) within the Air Ministry and Luftwaffe. Also, the use of intelligence turns out to be just as important as the access to it. In the case of German armored warfare, the U.S. Army had received detailed and accurate intelligence, but Mahnken notes: "That the Army did not immediately put this information to work had more to do with the priorities of the U.S. armed forces than with the quality of U.S. intelligence" (p.114). Finally, the story of the U.S. military's lack of curiosity about Britain's...