After Pearl Harbor, could the US have realized quickly that Japan would not strike the west coast?

by tim_mcdaniel

I did try a search here, but maybe I failed with my search terms, because I vaguely remember seeing a discussion.

The US had an initial great fear that, just after Pearl Harbor, Japan would attack the US's west coast. Of course Japan did not do much more than eventually shell an oil platform and launch explosive balloons.

I'm wondering the exact reasons why they didn't attack, but in particular what the US might have been known or plausibly surmised on 7 December 1941 and the next few days. The items that come to mind:

  • As I understand it, Japan's goal was to dominate East Asia. Capturing China, or at least the Good Parts edition of China, was the first means to the end. Seizing resources to the south was the means to the means to the end. Attacking the US was the means to the means to the means to the end. In short, they probably considered the US war to be an N-th level distraction to what they really wanted.
  • Fuel: did they have enough tankers? Did they have enough fuel?
  • Ammo and other equipment: had they gotten the 6 carriers to the US west coast, how much damage could they have done? I suspect there weren't many game-changing big juicy targets.
  • Risk: I expect they wanted the carriers and their planes for the Southern Resource Area, to take it and then to defend it. (So N-th level distraction, supra.) Putting a major fleet where the US could reach it with all the US's resources seems very risky. ... but did anyone think in December 1941 that carriers were so crucial, or was that a later realization? Without that realization, Japan or the US might have thought "eh, expend the carriers, they're expensive toys anyway".

But all that is my speculation.

DBHT14

Obviously there was great public worry and scares, as the LA incidents and the movie 1941 ably demonstrate.

However for large scale major fleet combatants there was relatively little worry from the Navy leadership and the Pacific Fleet.

For backing this up we can look at two deployment decisions, that of the Saratoga in the aftermath of Pearl Harbor and of TF-1 int he lead up to Midway.

The Sara represented 1/3 of the carrier strength in the Pacific and on December 7th had just entered San Diego harbor after a lengthy refit at Bremerton to pick up her air group. Had Navy leadership been truly worried about a follow up attack then logic dictates that she form a task force and remain in coastal water on patrol. Instead at the urging of Kimmel before his relief, then Pye, and King in Washington dispatched her with all possible haste to Pearl where she arrived on December 15th to join the Wake Island relief attempt.

We can however say that there was some concern for IJN submarines conducting super long range cruises off ports but the U-Boat threat in the Atlantic was always the more immediate and threatening. Task Force 1(the reaming battleships in operation) was based out of San Francisco. While rationalized as a protection against any attacks in reality Nimitz was looking for any and every excuse to keep them away from the Central Pacific as he felt them a liability. They were too slow to operate with carriers, guzzled oil from the limited refueling ships, and required carrier escort regardless. Additionally they ate up key destroyers that were needed elsewhere for escort duties.

So at the height of the war in the Spring and Summer of 1942 keeping the Navy's in some ways most vulnerable group of ships in California waters should show how worried leadership was of a fleet action there.

As for some of your specific questions I can help answer a few.

On the topic of Fuel Pearl Harbor stressed the IJN's fleet train to the limit, including having to use several merchant ships from Japan's already undersized merchant marine to use as Oilers. In fact the situation was so precarious that Admiral Yamaguchi(Commander of the 2nd Carrier Division) recommended either that the escort DD's be allowed to run out of fuel or that the 5th CARDIV CV's do the same and be towed back in order to add another 2 days for the time that the Kido Butai could remain on station or follow on strikes. That is just how close they were to the limit without either many more Oilers to create a relay, or a forward base to help out.

As for how the IJN thought of the carriers. They were considered important assets, as extremely costly and slow to be built by limited national shipbuilding infrastructure. However in general the IJN was always more aggressive and less conscientious of losses then their foes. This is in tradition with their experience and culture going back to their victory at Tsushima and the Naval Treaties causing Japan to look to maximize offensive firepower over almost every other concern in ship building. As in order to win with less tonnage they needed each ship to pack a larger punch when they could risks be damned. We see this demonstrated at Midway, with 3 of 4 burning and only Hiryu left again we meet Yamaguchi. Instead of retreating towards the Main Body the remaining ships of the Kido Butai screen Hiryu with the intent to let her strike back on the USN and then close for a night surface action, ignoring the obviously greater risk that placed their last fleet carrier at hand which was proven true when the 2nd wave of US Dive Bombers found and sunk her.

Let me know if you have any other questions or would like a book or two as suggestions!