H-Diplo Article Review 1023- "Frank Knox’s Fifth Column in Hawai’i"

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H-Diplo Article Review 1023

9 March 2021

Brian M. Hayashi.  “Frank Knox’s Fifth Column in Hawai’i:  The U.S. Navy, the Japanese, and the Pearl Harbor Attack.”  Journal of American-East Asian Relations 27 (2020):  142-168.  DOI:  https://doi.org/10.1163/18765610-02702003.

Article Review Editors: Thomas Maddux and Diane Labrosse | Production Editor: George Fujii

Review by John Prados, National Security Archive

“Frank Knox’s Fifth Column” is a distillation of the wartime secretary of the navy’s expressed suspicions that Japanese-Americans were in league with Tokyo. Knox made the allegation at a press conference a week after the December 7, 1941, Pearl Harbor attack, upon his return from a visit to that unfortunate base.  “Fifth Column” was a term coined during the Spanish Civil War to refer to subversion by other-than-regular military forces, in this case spies, and Knox at first believed they had been critical to the success of the Japanese attack that triggered American entry into the war.

As Brian Hayashi points out in this paper, it matters whether Knox referred to Japanese citizens alone, or was making a ‘racialist’ slur against Japanese-Americans. One could add that Knox’s suspicions might have focused on a tiny number of real spies and their abettors.  Hayashi takes that latter view, also arguing that the secretary’s aggressive ‘go-get-it’ attitude could not have abided the small number (relative to the entire Japanese-American population of Hawaii, 1,466 compared to 157,000) of Japanese-Americans arrested if he truly harbored racist opinions.

At the local level in Honolulu, the home of the 14th Naval District, which ran the Pearl Harbor base in support of the Pacific Fleet, the district intelligence officer was the man in charge of hunting down spies and protecting the forces from ‘fifth column’ activities.  Captain Irving R. Mayfield was that person, and his operatives (along with the Honolulu FBI office) were the ones alert to potential subversion.  It was Mayfield who held out for the smaller round-up of suspects, had wiretaps on the actual enemy agents, and followed the antics of the Japanese ‘outside’ spy, the agent Otto Kuehn, of German ethnicity.  Mayfield believed, correctly, that Tokyo obtained its espionage information by means of transmission through diplomatic channels.  That automatically made the office of the Japanese consul general in Hawaii the focus of counterespionage interest.

Hayashi presents evidence on the relationships between the Japanese consul general and various segments of the Japanese-American population, which included people who held dual citizenship, but broadly and overwhelmingly considered themselves patriotic Americans. There were closer relations with certain citizens—community leaders, religious figures, some others—who were asked to supply certain information.  This represented an unreliable source at best.  The community in fact could not be mobilized as a fifth column, and even those inclined to help had little idea of what constituted important intelligence.  On December 4, 1941 there were 212 names of community leaders on the list maintained by 14th District together with the FBI.  To avoid further disruptions in U.S.-Japan relations, Washington actually opposed arresting these people.

At a higher level were those Japanese-Americans actually employed by the consulate, as gophers, drivers, and so on. There were seven of these persons.  In addition there were a small number of others, restaurant owners, Japanese immigrants, and the like, who made willing participants. These people could actually be tasked, but again, a stumbling block remained what to look for. One consulate official played the role of intermediary on intelligence matters, and a special series of foreign ministry cables conveyed intelligence requests.  But the consular official was a diplomat, not an intelligence officer, and not until late in the game (just eight months before the Pearl Harbor attack) did the Japanese Navy send an officer with professional knowledge to captain Japanese espionage efforts at the consulate.

American naval officers also feared that Japanese-Americans might conduct sabotage, with or without cooperation from Japanese submarines offshore. Hayashi shows Admiral William F. Halsey as vocal in this regard, along with a few men on the Pacific Fleet staff.  Other officers did not hold that view, and Secretary Know himself is quoted as having been worried more about defeating Germany than the war in the Pacific.  The paper actually trails off at this point. There is no evidence of sabotage on Hawaii or any of the other islands, and Hayashi finishes by observing that American officers had high opinions of the skills of their Imperial Japanese Navy opponents.

So where does that leave us?  The basic information has been on the record since 1946, with the Pearl Harbor Attack hearings.[1]  There were vociferous debates about the internment of American citizens of Japanese descent.  Through the next decade and more the fancied ‘threat’ from Japanese-Americans seemed steadily less. The recollections of Japanese Navy spy Yoshikawa Takeo appeared in the United States in 1960.[2] By then the innocence of Japanese-Americans should have been plain. In 1967, in his book Broken Seal, historian Ladislas Farago wrote of the Pearl Harbor spies in considerable detail, including the consulate’s activities, the official spies versus those citizens who chose to participate, the community figures, the Kuehn ‘outside’ spy, and more.[3] Subsequent historians have written in the same vein.  But entrenched notions live on, and unfounded suspicions seem to recur repeatedly.  Brian Masaru Hayashi should be commended for reminding us of the record.


John Prados heads the National Secuity Archive’s Intelligence Documentation Project and its Vietnam Project, assists on other subjects, and is a Senior Fellow on national security affairs, including foreign affairs, intelligence, and military matters.  He holds a Ph.D. in Political Science (International Relations) from Columbia University and has authored many books, most recently The Ghosts of Langley: Into the CIA’s Heart of Darkness (The New Press).


[1] U.S. Congress (79th Congress, 1st Session).  Joint Committee on the Investigations of the Pearl Harbor Attack.  Hearings Before the Joint Committee on the Investigations of the Pearl Harbor Attack.  Washington: Government Printing Office, 1946.

[2] Yoshikawa Takeo with Norman Stanford, “Top Secret Assignment,” United States Naval Institute Proceedings, v. 86 (December 1960): 27-39.

[3] Ladislas Farago, The Broken Seal: ‘Operation Magic’ and the Secret Road to Pearl Harbor (New York: Random House, 1967), 47.