(1) The extent to which FDR and the highest levels of the US armed forces recognized that an attack on Pearl Harbor was both possible and a risk that had to be prepared against;
(2) What warnings of the impending attack, if any, were delivered to FDR and other relevant decision-makers; and
(3) The degree, if any, to which these warnings were deliberately ignored and suppressed by FDR and his associates so that a sudden Japanese attack on Pearl Harbor would assure that the US would enter WW II with a sense of unity and resolution in spite of powerful isolationist sentiments among the American public.
You argue that an attack on Pearl Harbor was not seen as plausible because it was contrary to US and Japanese war plans. The historical record is otherwise. By January of 1941, an attack on Pearl Harbor was feared at the highest levels of the War Department and the Navy and the Pacific Fleet was so informed. The essential documentation was collected and preserved as Exhibit 40 of the Hart Inquiry.
The opening passage of the first letter in January of 1941 to the Secretary of War from Secretary of the Navy Frank Knox makes abundantly clear that a surprise Japanese aerial attack on Pearl Harbor was seen as a distinct possibility:
The security of the U. S. Pacific Fleet while in Pearl Harbor, and of the Pearl Harbor Naval Base itself, has been under renewed study by the Navy Department and forces afloat for the past several weeks. This reexamination has been, in part, prompted by the increased gravity of the situation with respect to Japan, and by reports from abroad of successful bombing and torpedo plane attacks on ships while in bases. If war eventuates with Japan, it is believed easily possible that hostilities would be initiated by a surprise attack upon the Fleet or the Naval Base at Pearl Harbor.
In my opinion, the inherent possibilities of a major disaster to the fleet or naval base warrant taking every step, as rapidly as can be done, that will increase the joint readiness of the Army and Navy to withstand a raid of the character mentioned above.
The dangers envisaged in their order of importance and probability are considered to be:
(1) Air bombing attack.
(2) Air torpedo plane attack.
(3) Sabotage.
(4) Submarine attack.
(5) Mining.
(6) Bombardment by gun fire.
Defense against all but the first two of these dangers appears to have been provided for satisfactory.
My we take point 1 as established between us, that the risk of a surprise carrier attack on Pearl Harbor was in fact recognized well before December 7, 1941?
Exhibit 40 makes good reading and I made a copy to keep with my Prange book. However, delivering an attack by twelve squadrons would require every CV the Japanese had and then the decks would be empty of aircraft leaving nothing to defend the task force or launch a counter attack. The Japanese added two CVL’s for Pearl Harbor. When Yamamoto took six carriers he left the complex and extensive southern operations almost totally dependent on land based aircraft. Those folks were not happy and had opposed him vigorously.
In stating the maximum, the writer makes a speculation unexampled by actual operations or any war gaming. I remember a 1930’s Navy exercise involving attack by a single carrier on the Panama Canal, so I am willing to believe that my source on the subject of multiple carrier operations has done his homework. I said the attack was possible and therefore plausible, but not probable. Sorry about that terrible sentence, but must have been just too tired to wordsmith it properly.
Naval History: Pearl Harbor’s Overlooked Answer
http://www.usni.org/magazines/navalhistory/2011-12/pearl-harbors-overlooked-answer
Yes, we can certainly agree on point One. It agrees to my first post which said, “Revisionists offer arguments that FDR, Cordell Hull, and George Marshall foreknew the Pearl Harbor attack. These authors review historical events for those few data points that indicate an overwhelming attack. However, living history forward means accumulating and discerning patterns from 10,000’s of data points coming from humint, radio traffic analysis, code breaking, etc…..
The attack was a truly unexpected and improbable use of the Japanese air fleet.”