Pearl Harbor: Who Blundered?

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One, dated November 15, was already old; its translation had been deferred for several days in order to take care of messages considered more urgent. It referred to an earlier message directing the Japanese consulate at Honolulu to make periodic reports on the location of American warships in Pearl Harbor, and requested the Honolulu consulate to step up these reports to twice a week.

No particular importance was attributed to this by Admiral Stark or his senior naval intelligence officers, since the Japanese had long been making efforts to obtain information about the activities and number of ships in harbor at other naval bases on the West Coast and at Panama. The fact that the Japanese wanted more complete data, including exact locations of specific vessels in Pearl Harbor, was assumed to be merely an indication of their thoroughness in evaluating intelligence on America’s main Pacific combat force.

The other message was a reply by Prime Minister Tojo to the suggestion of his ambassadors at Washington that peace could perhaps be preserved through a high-level conference—they had proposed former Premier Prince Konoye as the Japanese envoy and Vice President Henry Wallace or Presidential Assistant Harry Hopkins for the United States—at “some midway point, such as Honolulu.” Tojo’s response, that “it would be inappropriate for us to propose such a meeting,” seemed a less significant indication of Japan’s immediate intentions than the continuing reports of her movements in and near Indochina.

Honolulu, Wednesday, December 3

Admiral Kimmel noted the continuing and surprising lack of information on Japanese carriers contained in the latest daily radio intelligence summary, which stated that “carrier traffic is at a low ebb.”

That day, too, he received Admiral Stark’s letter of November 25. He agreed with Stark’s view that “an attack on the Philippines” might be embarrassing, but that “an advance into Thailand, Indochina, Burma Road area [was] most likely.”

In the afternoon Short and Kimmel conferred. They soon got into a grim discussion of what they could do to carry out assigned war plans when and if war broke out. Both were thinking, of course, of planned naval and air raids into the Marshall Islands and of security measures for Wake and Midway. There was no mention of like measures for Oahu. Nor did Admiral Kimmel think to mention to General Short his latest intelligence reports about the burning of Japanese codes or the missing aircraft carriers.

[Nagumo’s planners on the high seas were busy marking on their charts of Pearl Harbor the exact locations of six of the U.S. battle fleet—the Pennsylvania, Arizona, California, Tennessee, Maryland, and West Virginia. The data came from Honolulu, relayed by radio through Imperial Navy Headquarters in Tokyo.]

Washington, Thursday, December 4

A mixed bag of Magic intercepts available to both Stark and Marshall gave clear indication of Japanese intentions to go to war. Instructions came to Ambassador Nomura to completely destroy one of the two special machines for secret coding, but to hold the other and its cipher key—which should be in his personal possession—“until the last minute.” One intercepted message, considered to be relatively insignificant, was to the Japanese consul at Honolulu; he was to “investigate completely the fleet-bases in the neighborhood of the Hawaiian military reservation.”

Stark and Marshall concerned themselves with routine activities.

Honolulu, Thursday, December 4

Admiral Kimmel conferred with two of his senior task-force commanders, scheduled to sail the next day on combined training-alert missions. One, under Vice Admiral Wilson Brown, was to proceed to Johnson Island, 700 miles southwest of Oahu, on a joint Navy-Marine bombardment and landing exercise. The other, under Rear Admiral T. H. Newton, included the carrier Lexington. This force was to go to Midway Island, fly off a squadron of Marine planes to reinforce the local garrison, and then rendezvous with Brown at Johnson Island. En route the Lexington’s planes would conduct routine scouting flights.

Kimmel’s intention was that, should war break out, these forces would be available for raids into the Marshall Island group in accordance with existing war plans. Both task-force commanders understood their war-plan missions; both were aware in general of the tense international situation. Kimmel, therefore, felt he was under no obligation to inform either of Washington’s November 27 “war warning” message.

The net naval situation on Oahu now was that the entire carrier force of the Pacific Fleet was either at sea or about to steam and that the approaches to the island from the west would be scouted for several days to come.