Samuel Eliot Morison and later political scientist John Mueller have
made the argument that the Japanese attack on Pearl Harbor, although
intended to guard the flank of the southward advance into the East
Indies and Malaya,was actually superfluous to that campaign (and the
battle for the Philippines) because the US Pacific fleet units at
Pearl were not in shape to intervene effectively in western Pacific
waters. *They further argue that even if the US had the freedom of
action to try to send the Pacific fleet to Asia after December 8th,
the chances of major fleet and crew losses in deep waters in the areas
of the Japanese mandates were high, and the chances of of successfully
preventing Japanese conquests of the Indies and Malaya (and
Philippines) by such a desperate intervention were *nil*.
The thing that Mueller and Morison both left out of their analyses was
what US forces in the Philippines were capable of doing in Southeast
Asia.
The US had growing ground and air forces in the Philippines, and the
Asiatic Fleet in its waters. *The platforms there were generally
inferior in quantity and quality to those available in Hawaii and
CONUS (except for some bomber aircraft), but they were all positioned
much closer to the scene of Japanese fighting with the British and
Dutch than the forces at Pearl.
Supposing the Japanese attack the British and Dutch throughout
Southeast Asia by December 8th, 1941, while leaving US territories and
assets alone, and add some of the forces they actually allocated to
the Pearl and Philippines attacks to strengthen the Indies, Malaya and
New Guinea attacks, what risks would this have imposed on the Japanese
in the *near* term, like through March-April 1942?
Further supposing that the Americans make the political decision to
declare war within a week of 8 December, begin providing immediate
covert support and are willing to use all available forces in any
operations no matter how high the risk to aid the British and Dutch
and oppose the Japanese from say the 18th of December onward, could
they make themselves into a critical threat to Japanese operations, or
just a mere annoyance?
To sketch it out further, let's assume that from the 9th of December,
the US command in the Far East begins full intelligence sharing with
the British and Dutch, and permits their units to take refuge in
Philippine terrritory and waters if it becomes tactically necessary
and proper? *Further, US fleet units that may happen to be in British
and Dutch Southeast Asian ports do not retreat from the combat zones
and fire on the Japanese if fired upon. *Finally, in the most
aggressive initial policy, from the 8th through the 18th, US submarine
commanders are authorized to attack Japanese vessels from submerged
positions where there is plausible deniability and this can be
attributed to British submarines.
After 18 December, open participation by fleet and air units is
authorized.
If under these circumstances, the Japanese stay focused on their
territorial and force-on-force objectives against the British and
Dutch, do not escalate against the Americans and only fire on American
units that fire on them in the middle of combat zones outside US held
territory (ie, the Philippines and Guam), at least through the rest of
December, would Japanese progress in occupying the Indies, Malaya and
Singapore *have been any less than in real life?
I say no. *If the Japanese remained sanguine about flank threats their
conquest of the British and Dutch empires in Southeast Asia would have
remained on the historical schedule or ahead of it. *The main
difficulty they would face longer term would simply be that when the
Japanese turn to deal with the Americans in the Philippines, the
Philippines can be defended for longer. *However, *effective* use of
U.S. assets from east of the international dateline to help the
Philippines before May 1942 would be impossible, and such forces even
for the remainder of 1942, or through the fall at least, would *be at
most an irritant rather than a decisive block to Japanese forces in
the Philippines, and could achieve this irritating effect, only at
high risk to themselves.
*