A lot has been written on how we missed out on predicting Pearl Harbor as the location of the initial Japanese attack. It strikes me now that one reason was that Pearl was not that important of a target in the overall Japanese war effort.
Consider the warning message of 24 November:
CHANCES OF FAVORABLE OUTCOME OF NEGOTIATIONS WITH JAPAN VERY DOUBTFUL. THIS SITUATION COUPLED WITH STATEMENTS OF JAPANESE GOVERNMENT AND MOVEMENTS THEIR NAVAL AND MILITARY FORCES INDICATE IN OUR OPINION THAT *A SURPRISE AGGRESSIVE MOVEMENT IN ANY DIRECTION INCLUDING ATTACK ON PHILIPPINES OR GUAM IS A POSSIBILITY*. CHIEF OF STAFF HAS SEEN THIS DESPATCH CONCURS AND REQUESTS ACTION ADEES TO INFORM SENIOR ARMY OFFICERS THEIR AREAS. UTMOST SECRECY NECESSARY IN ORDER NOT TO COMPLICATE AN ALREADY TENSE SITUATION OR PRECIPITATE JAPANESE ACTION. GUAM WILL BE INFORMED SEPARATELY.
And the followup “war warning” of 27 November (which went to the commander of the Asiatic Fleet, and others):
THIS DESPATCH 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 ORGANIZATION 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 WPL46*. INFORM DISTRICT AND ARMY AUTHORITIES. A SIMILAR WARNING IS BEING SENT BY WAR DEPARTMENT. SPENAVO [Special Naval Observer, U.S. officer assigned to the RN] INFORM BRITISH. CONTINENTAL DISTRICTS GUAM SAMOA DIRECTED TAKE APPROPRIATE MEASURES AGAINST SABOTAGE.
Not only didn’t it mention Hawaii, but the further away from the Far East it looked, the less it talked about naval action. Guam and Samoa and the Continental districts of the US were alerted against sabotage. Even with Magic, information gleaned from Japanese diplomatic codes, our warnings were aimed at the Far East.
In part, this is because the Japanese were aiming their main thrust south — Borneo, Malay Peninsula, Indonesia. We were tracking a major surface fleet headed that way, dozens of ships with thousands of troops, enroute to invade Malaya. They had hundreds of land-based aircraft at airfields in newly-occupied Cochinchina. This wasn’t just a main thrust, it was the whole reason for the war.
Pearl Harbor, from a force deployment perspective, was almost a side show. It was a head-fake, a bump-and-run. Yes, they felt that success at Pearl was vital to giving Japanese forces freedom of action at the start of the war, but it was like depending on a key block to make sure a large, complex play can run*.
*Hey, I’m doing the best I can — I don’t even like football.