WI: Japanese attack on Pearl Harbor before Barbarossa?

[Rufus]

Let's say Japan occupies the entirety of Indochina after the fall of France in 1940, and US-Japanese relations go south much more quickly. Consequently, the US enacts its oil embargo in 1940, a year earlier than OTL. Japan then starts preparations for the conquest of South-East Asia much earlier, and attacks Pearl Harbor sometime in the first half of 1941 (let's say February or March).

What would the effects of an earlier outbreak of the war in the Pacific be, especially in regard to:

1. The relative strengths of the American, Japanese and British forces in the region compared to late 1941/early 1942

2. The German reaction to Japan's actions. By early 1941 the US Navy hadn't yet started to escort convoys all the way to Iceland, and there had been no clashes between German and American ships or UBoats yet. Will Hitler declare war on the US that early, even before the launch of Barbarossa?

3. If Germany doesn't declare war on the US yet, and the US war effort will be focused on Japan at the moment, how will that change American planning in the Pacific?

4. Effects of an earlier outbreak of war in the Pacific on the situation in Europe, North Africa and the Battle of the Atlantic (especially if there is no immediate German DoW on the US).

5. Possible other, less obvious effects?

 

[Post]

The attack would have to be performed with two carriers less, as the Shokako and Zuikaku were commisioned in august and september 1941.

 

[RMcD94]

I think this is really fascinating question.

You have to consider that everyone in this situation is weaker but without some carriers Japan is perhaps comparatively weaker than the others.

Not only that the differences between the weather of the OTL Pacific War and this ATL version will no doubt be significant in many situations.

1941 Pacific typhoon season - Wikipedia

en.wikipedia.org

I have to think the union of Italy, Germany, the USSR and Japan into a single block will seem terrifying for the West. Admittedly the USSR is not yet at war but with Australia and New Zealand it will seem that there is no possibility of respite. With no Eastern front it would seem like Germany can focus on Britain leaving ANZ to fend for themselves.

The moral situation certainly is meaningful, though if Barbarossa happens on schedule then you have to think of the reverse issue in Japan where suddenly their allies are fighting amongst themselves while they're in total war.

 

[Lawnchair Captain]

Another problem for the Japanese would be that they would be attacking the US before they had gained control of the French Indochina (and before the oil embargo by the US prompted by such occupation which was one of the reasons why they went to war but maybe we could assume that the Japanese high command had decided that war was inevitable and so they had to attack now).

Naturally they would occupy the French Indochina before they moved to Malaya without any resistance by Vichy France but maybe this would give time for the British to send more forces to Malaya and prepare the defense better there. On the other hand the British were pretty stretched everywhere in the first months of 1941. Who knows, depending when this happens, maybe this would stop Churchill from sending forces to Greece when the Australian government would ask for the Australian divisions to be send back home.

That could mean a movement of forces from Britain to Egypt and from Egypt to Australia (and if Churchill was convincing enough to Malaya but I'm not sure that they would arrive in time.

 

[David T]

One thing this ignores is that Barbarossa may have been a factor in FDR's increasingly tough policy toward Japan:

Roosevelt viewed the Soviet Union as an indispensable
belligerent against Hitler and took the threat of a
Japanese invasion of Siberia from Manchuria quite
seriously; there is even evidence that he deliberately
stiffened U.S. policy toward Japan in the wake of
Germany’s invasion of Russia for the purpose of
encouraging the Japanese to look south rather than
north.26 “The great question for world leaders in the
first half of 1941 was whether Hitler would attack the
Soviet Union, and the great question in the latter half
was whether he would succeed,” observes Waldo
Heinrichs. “The German-Soviet conflict had a direct
bearing on Japanese-American relations.”27

https://webcache.googleusercontent.com/search?q=cache:VftXGX9eefAJ:https://www.hsdl.org/%3Fview%26did%3D38470+&cd=14&hl=en&ct=clnk&gl=us

 

[Garrison]

Well I suspect that even if Hitler hesitates to declare war on the USA when the Japanese attack he may well do so in the first flush of success of Barbarossa. The basic strategic logic of the declaration still holds, Lend-Lease, the escalating undeclared war with the USN in the Atlantic and the desire to unleash the U-Boats in US coastal waters all still held true.

 

[Rufus]

Another problem for the Japanese would be that they would be attacking the US before they had gained control of the French Indochina (and before the oil embargo by the US prompted by such occupation which was one of the reasons why they went to war but maybe we could assume that the Japanese high command had decided that war was inevitable and so they had to attack now).

Well, my idea is that Japan occupies all of Indochina in 1940, after the fall of France, which then leads to earlier US sanctions, which in turn leads to earlier Japanese preparations for war. Basically, the whole timeline of events leading up to the war is sped up.

I have to think the union of Italy, Germany, the USSR and Japan into a single block will seem terrifying for the West. Admittedly the USSR is not yet at war but with Australia and New Zealand it will seem that there is no possibility of respite. With no Eastern front it would seem like Germany can focus on Britain leaving ANZ to fend for themselves

On the other hand the British were pretty stretched everywhere in the first months of 1941. Who knows, depending when this happens, maybe this would stop Churchill from sending forces to Greece when the Australian government would ask for the Australian divisions to be send back home.

That could mean a movement of forces from Britain to Egypt and from Egypt to Australia (and if Churchill was convincing enough to Malaya but I'm not sure that they would arrive in time.

With the prospect of a potential (real or imagined) German-Soviet-Japanese block arrayed against them, how likely is it that Britain would accept a German peace proposal, if Hitler made another one like after the fall of France? Might the British see it as preferable to focus on the Japanese first, while preparing for a possible round two with the Germans later?

One thing this ignores is that Barbarossa may have been a factor in FDR's increasingly tough policy toward Japan:

Roosevelt viewed the Soviet Union as an indispensable
belligerent against Hitler and took the threat of a
Japanese invasion of Siberia from Manchuria quite
seriously; there is even evidence that he deliberately
stiffened U.S. policy toward Japan in the wake of
Germany’s invasion of Russia for the purpose of
encouraging the Japanese to look south rather than
north.

That's a good point. Though if Japan's aggressive moves happen earlier, then FDR might fear that Japan is making preparations for an attack on the British Empire while Britain is still fighting Germany alone, and the German-Soviet alliance still stands. So he might adopt a tougher stance against Japan to give the impression that the US will fight alongside Britain if Japan makes moves against British possessions in Asia. This would either force the Japanese to stand down, or force them to attack the US (like OTL). Either case helps Britain.

 

[Anarch King of Dipsodes]

One thing this ignores is that Barbarossa may have been a factor in FDR's increasingly tough policy toward Japan:

"Roosevelt viewed the Soviet Union as an indispensable belligerent against Hitler and took the threat of a Japanese invasion of Siberia from Manchuria quite seriously; there is even evidence that he deliberately stiffened U.S. policy toward Japan in the wake of Germany’s invasion of Russia for the purpose of encouraging the Japanese to look south rather than north.

After BARBAROSSA. And it seems most unlikely that FDR thought that a Pacific War to distract Japan was any kid of sensible idea. Such a war would include Japanese attack on Britain et al in SE Asia, which would be a massive blow to the Allies. AIUI, FDR and Churchill by late 1941 were hoping to deter Japan from attaching so the US and Britain could stay focused on Europe.

Bear in mind that US suppory for China was a thing before BARBAROSSA. However, ISTM very difficult for tensions to ramp up to war by June 1941. The process can't start till after the 1940 US election. OTL it took 13 months from then; for this ATL it has to happen in 7 1/2 months. And that has to include time for the IJN to develop the technique for air dropping torpedos in shallow water that was required. Hard to get there....

Also, how long before BARBAROSSA? If 2 months before, does Hitler reconsider BARBAROSSA? (I.e. with the US coming in against the Axis). What if it's the day before?

How about this? By sheer coincidence, Japan attacks PH and Malaya the same day as the Germans invade the USSR. Because they're not talking to each other. But Americans would see it as proof of The Plot.

 

[mattep74]

Why would they? It was not until late July 1941 that the USA started their embargo and forced Japan to action

 

[nbcman]

Well, my idea is that Japan occupies all of Indochina in 1940, after the fall of France, which then leads to earlier US sanctions, which in turn leads to earlier Japanese preparations for war. Basically, the whole timeline of events leading up to the war is sped up.
{snip}

Unfortunately that doesn't work for everything. Such as the monsoons that would have shut down operations in Burma in May 1941 and the monsoons which would have impacted operations in Malaya between May and October. Shifting a time table up doesn't make the weather conditions change-and a midyear attack on SEA is not a good time weatherwise to do it.

 

[Rufus]

Unfortunately that doesn't work for everything. Such as the monsoons that would have shut down operations in Burma in May 1941 and the monsoons which would have impacted operations in Malaya between May and October. Shifting a time table up doesn't make the weather conditions change-and a midyear attack on SEA is not a good time weatherwise to do it.

Which is why my idea is that Japan attacks early 1941, as stated in my OP.

 

[nbcman]

Which is why my idea is that Japan attacks early 1941, as stated in my OP.

OK, but that trims 3-4 months off the favorable weather window in SEA. Assuming a similar time frame, it would be a race to Singapore before the Monsoons would impair the advance and it would be unlikely that the Japanese could advance into Burma.

It would also screw Nazi Germany as they would most likely miss out on their significant spring 1941 natural rubber deliveries from India purchased by the Soviet Union due to the earlier start of the war in the Pacific.