Another amusing 'what if' that came out of the current series of 'what if' articles. Enjoy.
What if Japan had made a serious effort to finish off the USN first? Rather than shifting most of their attention back to Malaya, the East Indies, Darwin, and the Indian Ocean for 5 or 6 months, and allowing the USN so much time to recover?
And by that, I mean what if Japan had at least followed through with at least a third strike on Pearl Harbour, or, better, with an actual invasion of Hawaii.
(See my previous post on the debate over Japanese plans for such an invasion of Hawaii. Yamamoto and Nimitz both stated categorically that not following through was the greatest mistake the Japanese ever made.)
What if the Japanese had pro-actively concentrated on a 'USN first' strategy, and left the 'clean up' against their other flank until they were completely sure the USN threat was properly undermined?
What if they had concentrated most of their resources from December 1941 until May 1942 on completing the destruction of the USN – rather than wandering backwards and forwards to raid Darwin and the Indian Ocean – before trying to force a Midway style conclusive battle?
If they had substantially reduced the USN in that way, then the Midway style 'decisive battle' plan would have been aimed at the British Eastern Fleet at Ceylon instead.
The two front trap...
Trying to solve the two front trap was the defining issue for aggressors in both World War's. The Schlieffen Plan of WW1, and the Pearl Harbour/Indian Ocean raids of WWII: were both samples of how failing to solve this issue guaranteed losing the war.
Japan's problem was that they couldn't risk seizing British and Dutch possessions without dealing with their vulnerable flank against the US.
Equally, they couldn't risk dealing with the US without opening their vulnerable flank against potential British/Dutch counter operations. (It's not just the 'possible', 'eventual', threat of a British fleet strong enough to mount an actual offensive they had to fear. Don't underestimate the immediate threat of those dozens of Dutch submarines based in Java against vital Japanese communications in the South China Sea between their homeland and their forces in China and Indochina.)
However it is interesting to speculate on whether it would have been more sensible for the Japanese to concentrate their first few months on the Americans, just assuming the British would not be in any position to mount a major counter threat for many months? (A pretty realistic assumption in early 1942.)
Could that have been more effective than splitting Japanese forces between operations against everyone simultaneously?
In reality of course, we know that the impressive looking efforts careening all over 1/3 of the globe trying to take out the USN at one end and the RN at the other end: just meant that neither was really defeated badly enough to be driven from the field more than temporarily. Despite the Allies slower battleship units sometimes being pushed back as far as the African or US West Coasts, worryingly strong Allied mobile forces always remained hovered around the Indian Ocean and Central and South Pacific. Forces quite capable of mounting Doolittle raids; invasions of Madagascar; spoiling attacks on the Andaman's; or around New Guinea; or at Guadalcanal.
But instead of concentrating on finishing off one opponent or the other, the IJN just rushed backwards and forwards to more and more frantic attempts to achieve 'decisive' results here or there, usually with ever decreasing numbers of planes operating from less and less carriers each time.
What could they have achieved by concentrating on one opponent at a time?
Properly taking out one ally at a time?
I think we have to accept that the IJN simply couldn't take its whole navy to deal with the RN in the Indian Ocean in December 1941with an undamaged USN 'at peace' on its flank. Their logic in thinking they had to reduce the threat from the USN even just temporarily if they were going to attack the British Commonwealth, is pretty unassailable.
But should we write off the idea that they might have concentrated practically their whole navy on the USN for the first 4 or 5 months, before worrying about cleaning up Malaya and the Netherlands East Indies? Decisive victory on one front should automatically allow for a much better attempt at decisive victory on the other front. Particularly as the RN needed at least 5 or 6 months to gather a reasonable force for even defensive operations, let alone for offensive ones.
But in this scenario, it would be far easier to completely finish off the threat from the USN (at least for several years), while reversing the 'final battle' strategy for use against the RN instead!
With the USN reduced to impotence, and the main Japanese fleet based at Singapore (which it actually was sometimes, even under the two front threat), then the IJN had a real chance of enticing the British into a decisive 'Battle of Tsushima' in mid to late 1942.
Consider a Midway style operation, but aimed at Ceylon, and with no effective USN to threaten its flank? If the Japanese had garrisoned Hawaii and Midway already, and done a couple of Darwin/Indian Ocean style raids on the US West Coast (hopefully reducing the USN to only one active carrier the way they actually did in late 1942 anyway): then such a Midway style operation might not even lack Shokaku and Zuikaku? (Admittedly the attrition rates of such a series of attacks would still see much reduced squadron numbers, and a lot of less skilled pilots, in the Japanese carriers. But it is still a sobering thought.)
Should the IJN have had its own 'Germany First' policy, on the same logic basis of knocking out the greatest threat, and dealing with the less immediately capable foe later?
Should Japan have gone full 'USN first'?
Most sensible strategists would probably say yes. If you are going to throw the dice in taking on too many enemies, then concentrating on a decisive blow against one of them before spreading your forces against several is pretty much Strategy 101.
But would it have made a difference?
In reality all the wandering back and forth for 6 months prevented the IJN from concentrating a strong enough strike to win at Midway. (Though there was still a lot of luck involved in the US victory.)
But frankly their situation might have been in no way improved had they spent those 3 or 4 months decisively defeating the USN, and given the RN the breather it needed to get a proper force in place in time to face whatever the much reduced IJN could throw at them after occupying Hawaii and bombing US West Coast bases.
In fact it might come down to whether they IJN could get the USN out of the way and re-concentrate against the RN by April 1 (when the Indian Ocean raid actually happened... probably the last time they had a really good chance), or if it still would have had to wait until at least May (Coral Sea), or June (Midway itself).
The delay until at least May, and very probably until June, might have been enough to change everything...
A June 1942 'decisive battle'... of Ceylon?