By Nolan Nelson
One enduring conspiracy theory is that Franklin Delano Roosevelt, George Marshall and Cordell Hull had foreknowledge of a potentially devastating Pearl Harbor attack and used the event to precipitate U.S. participation in WW II. In general revisionists start with the determination that the Japanese had to fire the first shot in order for the Administration to get the backing of the American people. Looking backwards they piece together specific data points to prove these men must have known the attack was coming.
However, they have had to ignore the fact that these men were living out history forwards. The information the U.S. received from traffic analysis, informants, investigations, and code braking swam in a sea of 10,000’s of data points each month.
Remember a few years ago you could buy pictures that seemed a mass of random color pixels, but a single picture emerged if you stared at it in the right way? In this case a host of pictures emerged each week with each put forward by professionals who asserted this could be their true intention. To direct our limited resources for the coming war these possibilities had to be reduced to the most probable alternatives.
The Pearl Harbor attack was one of the least likely options for a host of reasons among the few now noted. First U.S. War Plan Orange and the corresponding Japanese plan, which was generally known to us, both envisioned the supreme naval battle would be fought in the Western Pacific. Both navies were disciples of Alfred Thayer Mahan who wrote the outcome of war at sea would always be decided by the “decisive naval battle”. Past history had borne that out at Trafalgar, Tsushima, and Jutland. For Jutland Churchill said, “Jellicoe was the one man who could have lost the war in an afternoon”.
For the Japanese enticing the U.S. Navy into a sea battle in the Western Pacific was the best option. Their ships of short operational range would not be at a disadvantage. Japan could use land based reconnaissance and attack aircraft in battles as we attempted to counter their attacks against Guam, the Philippines, etc. Ships lost at sea could not be recovered as they could if they were hit in harbor.
A counter argument was developed through the large scale U.S. Navy exercises between 1923 and 1940. These proved the feasibility of an increasing role for aircraft carriers in attacking bases like the Philippines, Panama Canal, and Hawaii. For example in 1932 Admiral Harry Ervin Yarnell commanded the carriers Lexington and Saratoga in an effort to demonstrate that Hawaii was vulnerable to naval air power. Yarnell’s planes attacked the harbor from the northeast, just as the Japanese would ten years later. The Navy’s war-game umpires declared the attack a total success, prompting Yarnell to strenuously warn of the Japanese threat.
However, the umpire’s final report did not even mention his success. Instead they wrote, “It is doubtful if air attacks can be launched against Oahu in the face of strong defensive aviation without subjecting the attacking carriers to the danger of material damage and consequent great losses in the attack air force.” The battleship admirals again successfully campaigned against reassessment of naval tactics being able to point to other exercises in which the vulnerability of aircraft carriers was demonstrated. Therefore, in this country War Plan Orange continued to determine the most probable interpretation to place on intelligence. Hence, there were many opportunities for self-deception, but not conspiracy.
The arguments for battleships that the U.S. admirals won was eventually lost by Japan’s Naval General Staff. When Yamamoto proposed this radical departure from Japanese strategic principles his firm commitment to resign at a meeting in October 1941 forced the Naval General Staff to accept his radical departure from existing plans.
Yamamoto’s plan was improbable and radical because never before had any country planned and/or coordinated an attack of such a size on a naval or land target. No inkling existed in any allied naval operational and intelligence community of a proven capability beyond the 21 Fairey Swordfish bi-plane torpedo bombers a single British carrier sent to attack the Italian Navy at Taranto. Even Admiral Yarnell used only two carriers and left no fighters for task force defense to launch 152 planes for the raid. Yet, for Pearl Harbor the Japanese forged a strategic weapon of six carriers with escorts and tankers for a coordinated mass attack by 360 planes with 55 retained to defend the task forces.
The attack deserved a low probability for consideration because it was not only unprecedented, but also unexpected. Preparations were conducted without recourse to the diplomatic Purple Code that U.S. codebreakers were reading in substantial portions. The U.S. had no agents in Japan and the Imperial Japanese Navy excluded their diplomats from all knowledge of the Pearl Harbor plan. To solve problems regarding bombing, torpedoes, and underway refueling the attack plan relied on oral doctrines and technical innovations developed during the last ninety days prior to deployment.
U.S. naval traffic analysis in Hawaii detected the same message flurry followed by radio silence as they had observed for tactical operations in February and July when major units had remained in port. Even though the Japanese had changed their fleet unit call signs December 1, Lieutenant Commander Layton says Commander Rochefort was still able to identify a large movement of fleet units south. However, they had no idea of the whereabouts of four carriers and could only assume they were still in home waters.
In briefing Admiral Kimmel, Layton could say the ships were probably in home waters, but confirmed Kimmel’s assertion they could possibly be steaming around Diamond Head without prior knowledge. Layton points to what he calls moral stupidity in the way the Washington intelligence community handled limited decrypts of the naval code (JN25) and the “bomb plot” message from a Purple Code decrypt. Once again the picture of a probable Pearl Harbor attack could have emerged for a few intelligence people only to be overcome by what many people expected to see.
This limited discussion of the Pearl Harbor conspiracy theorists covered only the likelihood the attack would be considered probable and/or of such a scale. Gordon W. Prange in writing At Dawn We Slept presented arguably the most scholarly, well researched volume on the attack from both the Japanese and American perspectives. The book ends with an eleven page summary refuting a host of revisionist imaginings including internal political collusion, secret treaties and international intrigues. The Broken Seal by Ladislas Farago also focuses on refuting the claim that FDR knew.