Date of Award


Degree Type

Open Access Dissertation

Degree Name

History, PhD


School of Arts and Humanities

Advisor/Supervisor/Committee Chair

Janet Farrell Brodie

Dissertation or Thesis Committee Member

Charles A. Lofgren

Dissertation or Thesis Committee Member

Ralph R. Rossum

Terms of Use & License Information

Terms of Use for work posted in Scholarship@Claremont.

Rights Information

© 2020 Sean-Patrick Lane


U.S. intelligence professionals, World War II, Japan

Subject Categories



This dissertation explores the perspective and performance of U.S. intelligence professionals and the intelligence organizations in which they served concerning Japan during the interwar period, the timespan ranging approximately from the conclusion of World War I in November 1918 through the entry of the United States into World War II in December 1941. Research for this dissertation focused predominantly on official and other primary documents, including U.S. intelligence reports and memoranda; intercepted, decrypted, and translated Japanese cablegrams; personal letters by and concerning U.S. intelligence professionals; and other primary source materials related to intelligence professionals and services available via the U.S. National Archives in College Park, Maryland. Some of these official and other primary documents were available from a number of online repositories providing access to U.S. intelligence documents concerning Japan during the interwar period. The published memoirs of particular key intelligence professionals, who focused particularly on Japan, and other actors, also proved important primary resources to completing this dissertation. Secondary sources augmented and occasionally corroborated the events related in the primary documents and memoirs. U.S. intelligence professionals produced intelligence informing U.S. civilian and military leaders of the increasing competition between U.S. and Japanese national interests and commercial objectives in the Asia-Pacific region, in addition to Japan’s perspective concerning the growing impasse. Particular intelligence professionals, whose exploits and experiences focusing particularly on Japan during the interwar period, provided an important foundation for this dissertation. These intelligence professionals took seriously the increasing threat that Japan posed to U.S. interests. For approximately two decades, they acquired intelligence from Japanese counterparts; defended U.S. interests against Japanese counterintelligence threats; and endeavored to influence their Japanese counterparts, often intelligence professionals and officers in Japan’s armed services, into reducing their concern regarding U.S. objectives in the Asia-Pacific region, particularly regarding Japan. In the end, war arrived in the form of a widespread and shocking series of Japanese attacks and invasions by sea, air, and land, reaching as far east as the waters just off of the California coast and targeting U.S., British, and Dutch military bases and colonies. The most famous aspect of the Pacific War’s start was the multiple air and sea attacks against Pearl Harbor and other U.S. military installations in the Hawaiian Islands, which sank of the U.S. Pacific fleet, claimed 2,403 lives, and caused the United States to declare war against Japan. Although some U.S. civilian and military leaders realized that war was increasingly likely as negotiations with Japan failed to yield solutions to U.S.-Japanese disagreements, the United States remained unprepared for war with Japan. Ultimately, the failure of U.S. leaders to use intelligence resources at their disposal and to empower intelligence collectors, in order to prepare the United States for a war with Japan, constituted a comprehensive leadership failure, rather than an intelligence failure.



Included in

History Commons