Flight paths of the Japanese attack force at Pearl Harbor by U.S. Government Printing Office/Wikimedia Commons
Part 3: Roosevelt's Success and the Lessons to Learn
In Part 1 and Part 2, we learned that although President Franklin D. Roosevelt wanted the United States to help Great Britain fight against Germany in World War II, the American public strongly opposed getting involved in another European war. In order to change public opinion, Roosevelt tried to provoke Germany into attacking the U.S. When that plan failed, Roosevelt changed his strategy to provoking Germany's ally, Japan, into attacking the U.S. This plan included economically isolating Japan while moving the Navy's Pacific Fleet to the relatively vulnerable base at Pearl Harbor, Hawaii.
On November 28 and 29, 1941, two messages were sent from Tokyo to the Japanese Embassy in Washington, which warned that "the negotiations will be de facto ruptured," but directed its staff not to inform the American government that negotiations would end. These messages were decoded on November 28 and November 30, respectively.
On November 30, two messages were sent from Tokyo to the Japanese Embassy in Berlin, which were decoded on December 1. These messages referred to the American proposals as "insulting" and "clearly a trick." They instructed the embassy staff to:
Say very secretly to [Hitler and Von Ribbentrop] that there is extreme danger that war may suddenly break out between the Anglo-Saxon nations and Japan through some clash of arms and add that the time of the breaking out of war may come quicker than anyone dreams.
Between November 27 and December 2, several messages between Tokyo and the Japanese Embassy in Washington were intercepted and decoded which included instructions regarding the code to be used for future communications. These messages also contained directions to destroy all other codes, code machines, and secret files. Similar instructions were sent to Japanese posts in Hong Kong, Singapore, Batavia, Manila, and London. According to Admiral Theobald,
Thus, when a nation orders her embassies and consulates in particular countries to destroy their codes, ciphers, code machines and files of secret correspondence, that action can mean only one thing - the close approach of war with those countries.
On December 4 and December 6, instructions were sent to U.S. bases on Guam and other outlying islands to destroy secret files and prepare to destroy their codes. However, this information was transmitted to Admiral Kimmel and General Short with low priority, which inferred that hostilities were not imminent.
On December 6, the American Minister in Budapest provided a British communique to the Hungarian government. The communique said that a state of war would break out on the next day, December 7. Since Great Britain was already at war with Hungary, the communique could only mean a war with Japan. According to Admiral Theobald,
Ambassador Winant from London also reported to Washington that a large Japanese amphibious force had been sighted off Cambodia Point headed for the Kra Peninsula and distant 14 hours' steaming therefrom. Every government concerned, including the United States, thus positively knew, on that Saturday, that the Pacific War would be initiated on the next day, Sunday, December 7.
The USS Arizona's forward magazines explode during the attack on Pearl Harbor. by U.S. Navy/Wikimedia Commons
On December 6, the War Department intercepted and decoded another message between Tokyo and the Japanese Embassy in Washington. This dispatch, called the "Pilot Message," instructed the embassy staff to prepare to translate into English a lengthy, separate message, which would be sent the next day. It was to be presented to the American government at precisely the time specified in the forthcoming message. As Admiral Theobald explained,
The recipients of Magic [Japanese communications that had been intercepted and decoded] in Washington had known for over a week that the Japanese reply to the American note of November 26 would be a declaration of war. The 14-part message was that answer, hence definitely a declaration of war. Japan had started her previous three wars - with China in 1894, with Russia in 1904, and her attack upon German-held Tsingtao in 1914 - with surprise attacks synchronized almost to the minute with the deliveries of her declarations of war.
The next day was Sunday, the day of the week upon which Japan was expected to deliver her surprise attack if she should ever decide to initiate a war with the United States. A Japanese amphibious force was known to be in position to make a dawn attack upon the Kra Peninsula the next day. During the earlier days of the week, the Japanese code-destruction messages made the imminence of war a certainty. The receipt of the Pilot Message made it practically certain that Japan would start the war on the next day, Sunday, December 7, 1941....
The Washington silence which followed the receipt of the Pilot Message was the most vital key to the true Pearl Harbor story. War within 24 hours, initiated by a surprise attack which, according to all the evidence, would be delivered upon the U.S. Fleet in Hawaii, stared General Marshall and Admiral Stark in the face from that moment onward, and they made no move during 21 of the 22 hours which intervened before the attack to inform Admiral Kimmel and General Short. Nothing but a positive Presidential order could have so muzzled them after the receipt of the Pilot Message.
The first 13 parts of the main message were intercepted by the Navy Department before 3:00 PM on December 26, and decoded by 9:00 PM. The final part was not transmitted until early the next morning. However, the first 13 parts "unmistakably indicated that they were part of a Declaration of War."
Two wrecked destroyers with the USS Pennsylvania in the background. by Harold Fawcett/Wikimedia Commons
The only explicit intelligence that Admiral Kimmel and General Short received about a possible attack have been called the "War Warning" messages. These messages were transmitted on November 27, after the American demands were given to the Japanese Ambassador in Washington. The message sent to Admiral Kimmel read,
This dispatch is to be considered a war warning. Negotiations with Japan looking toward stabilization of conditions in the Pacific have ceased and an aggressive move by Japan is expected within the next few days. The number and equipment of Japanese troops and the organizations of naval task forces indicates an amphibious expedition against either the Philippines, Thai, or Kra Peninsula, or possibly Borneo. Execute an appropriate defensive deployment preparatory to carrying out the tasks assigned in WPL 46. Inform District and Army authorities. A similar warning is being sent by the War Department. Spenavo inform British. Confidential districts, Guam, Samoa take measures against sabotage.
The message sent to General Short simply stated, "Negotiations with Japan appear to be terminated with only the barest possibility of resumption."