January 1939, Hitler has a dream where he sees that he will lose the war he is planning. Thus, he renounces to war and doesn't invade Poland. Mussolini does the same dream a few weeks later and similarly decides to avoid any open conflict.

Given the situation of Japan at that time, strengths and weakness of Japan/American armies, mindset of Japan leaders, ... I would like to know :

  • How would this have changed the Pacific war ?
  • Would Japan have attacked USA anyway with the risk to see the British empire putting all its forces in this war ?
  • Would Russia, France, Germany and Italy have been involved in this conflict ?

closed as primarily opinion-based by Gryphon, John, Blade Wraith, Secespitus, ArtificialSoul Aug 8 '18 at 12:01

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ As mentioned, any answer would be a lot of speculation. An important point, though I'm not sure how relevant, is that Hitler was so driven by racial hatred and a belief that the rest of Europe was weak and that stronger Germany would prevail, that a simple dream would never have caused him to abandon the war. As it was, Hitler didnt even believe that Germany was losing up until a few days before he committed suicide at the end of the war. $\endgroup$ – Sarah Stark Aug 7 '18 at 21:04
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    $\begingroup$ This question is extremely opinion based. It is impossible to conclude with any degree of certainty what would happen in such a situation. For example, "Japan not attacking" is as valid as "Japan bombs Pearl Harbor anyway, and loses the war quickly", which is as valid as "Japan bombs Pearl Harbor and things go nearly the same as they did in real life". $\endgroup$ – Gryphon Aug 8 '18 at 2:45
  • $\begingroup$ @Gryphon I agree but I think that most of worldbuilding SE questions are opinion based (e.g., worldbuilding.stackexchange.com/questions/30758/…). Here, I want to know the most likely changes in the Pacific war based on some facts such as the situation of Japan at that time, strengths and weakness of Japan/American armies, mindset of Japan leaders ... $\endgroup$ – user53220 Aug 8 '18 at 10:56
  • $\begingroup$ Holy broad question Batman! $\endgroup$ – Joe Bloggs Aug 9 '18 at 8:33

This is at best informed speculation.

I'm going to assume that Japan continued the war in China, which started before 1939. This was largely independent of European events. The Japanese would have been unlikely to invade Indochina with France remaining strong, but aside from that I'd expect something like the Pearl Harbor attack. The Japanese went into that attack knowing that they had very little chance of winning in any case, considering it a matter of national honor.

The US had some fairly strong forces in the Atlantic as of Pearl Harbor, and some US warships were involved in facing the Axis (including the carrier Wasp). They would have been available in the Pacific, and that makes it quite possible that the Japanese would have sunk a carrier at Pearl Harbor.

It seems unlikely that the Soviet Union would have gotten involved, as they had European interests to protect. They would likely have gotten more expansionistic. France would likely have stayed out if Indochina got left alone. The British are more of a question. Historically, Japan attacked the British as well as the US, so I'm going to assume the British were in the war. Germany had no interests in the Pacific. Given Hitler's dream, and Mussolini's lack of power, I'd expect Europe to remain at peace for some time.

The lack of a strong Navy to face in Europe would have allowed the British to send more naval forces to the Far East, and the British-controlled territories would be shielded from direct attack by the neutral French Indochina. This might have made the Japanese army more interested in fighting in the Pacific.

So, I'd imagine a somewhat different course for the Pacific War. One interesting thing is that the US sent most of its available resources against Japan in 1942, so not having the war in Europe would not have affected the initial course of the war all that much. The US juggernaut could not take place until the US had built enough aircraft carriers, so the Central Pacific offensive would have started pretty much on historical schedule.

One big difference would be the provision of landing ships and craft. Historically, the production of destroyer escorts needed for the Battle of the Atlantic cut heavily into landing ship production, and most of them were facing Germany until around the end of 1944 in any case.

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    $\begingroup$ For clarification, the US sent most of its available resources against Japan in 1942 while simultaneously pursuing a Germany First policy. In the absence of this agreement, Japan would be facing lot more American firepower a whole lot sooner than it did in reality, as was mentioned with landing craft production. $\endgroup$ – TKOW Aug 7 '18 at 23:51
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    $\begingroup$ Japan's war plan was based around the assumption that Americans didn't have the stomach for a long war, so it probably wouldn't be much different: they'd still assume that we'd rather have a quick and dirty peace rather than a long, expensive war. Although that leaves the interesting question: would they have invaded Indochina? It's not like they were particularly shy about making enemies, and they might've concluded that France wouldn't find it worth protecting. $\endgroup$ – Cadence Aug 8 '18 at 1:50

I do not believe Pearl Harbor would have happened anyways. Japan's motives for attacking Pearl Harbor were mostly about securing oil imports. The US had embargoed Japan in an attempt to stop their aggression in China. Attacking Pearl Harbor was an attempt to make the US back down. Without a war raging in Europe, it's possible that Japan could just have found a different source for oil; maybe Romania?

  • $\begingroup$ Congratulations! Good see to someone knows the reason for Japan attacking Pearl Harbor. Ironically the Japanese attack failed to destroy the US fuel reserves stationed at Pearl Harbor. If those had destroyed, the US war effort would have started off very badly. Apparently the Japanese overestimated the American capacity to replenish their fuel reserves. This was stored in large tanks in plain sight. $\endgroup$ – a4android Aug 8 '18 at 6:25
  • $\begingroup$ @a4android As I understand it, there was an additional (fourth?) wave of bombers intended to strike soft ground targets like the fuel tanks, but they were called off when the fleet commanders realized the American carriers were still at large. A counterattack by those carriers could've been devastating (it certainly was at Midway), so they decided to err on the side of caution and leave. $\endgroup$ – Cadence Aug 8 '18 at 12:56
  • $\begingroup$ @Cadence That's extremely interesting. I heard Japanese officers were debriefed about Pearl Harbor, post-war. They surprised to learn how vulnerable the USA would have been the fuel tanks had been destroyed. If the fourth bomber wave hadn't been called off, it might have changed the course of the War. Japan still would have lost, but the sequence of events have been different. $\endgroup$ – a4android Aug 8 '18 at 13:08
  • $\begingroup$ @Cadence Another reason for the last wave being canceled is that the fleet was nearly out of fuel. If they stayed any longer, they would have risked having to leave some of their auxiliary ships behind. $\endgroup$ – Ryan_L Aug 8 '18 at 15:48
  • $\begingroup$ There were two waves in the historical attack, so we'd be talking about a third wave, which would have had to be recovered at night if launched December 7. I don't know that it was actually planned in any way. At any rate, the purpose of the attack was to sink battleships and carriers. There were no carriers there, and the Japanese had sunk sufficient battleships, so there was no pressing need for another attack. $\endgroup$ – David Thornley Aug 8 '18 at 18:06

Without a European War that took out France and the Netherlands and had the attention of the UK, and had the USSR fighting for its life, Japan doesn't take the risk.

Note that despite the war between the USSR and Germany, Japan never poked the Russian bear, even when it was apparently on the ropes in 1941/1942, the result of thoroughly getting its ass handed to it in 1939 at Khalkhin Gol courtesy of Zhukov and the Red Army. That cautiousness would likely have extended to European powers not distracted by events at home.

Consider the strategic situation: Japan attacked Pearl Harbor because they needed to cripple the American fleet, because they had to attack the Philippines. They had to attack the Philippines because they needed to secure their flank in order to grab Indonesia and Indochina for their resources. But that meant they had to attack Hong Kong and Singapore to also secure their flanks. So they're already at war with Americans and the British. Attacking Indochina means bringing in the French. Attacking Indonesia means now the Dutch are in the mix as well, as they were in reality (although they were curb-stomped).

Just on the naval front, in 1939 the Royal Navy was still the largest in the world, with 15 battleships (+9 under construction), 7 carriers (+6 under construction), 65 cruisers of all sizes (+26 under construction), 113 modern destroyers (+24), 53 modern subs (+11).

The French had 7 battleships (+4), 1 aircraft carrier (+1), 19 cruisers (+3), 78 destroyers (+27), and 81 subs (+38).

By late 1941, the US had 17 battleships (+15), 7 carriers (+11), 43 cruisers (+40), 171 destroyers (+188), and 114 subs (+79).

The Japanese Navy, in December 1941, had 10 battleships (+3), 12 carriers (+7), 38 cruisers (+6), 126 destroyers (+43), and 68 fleet subs.

So, what does that mean? On the naval front, and using only the 1939 French and British numbers, in December 1941 the Japanese are outnumbered:

  • 39 to 10 in battleships;
  • 22 to 12 in carriers (given the superiority of Japanese naval aviation, this is actually pretty close, if not in Japan's favour);
  • 127 to 38 in cruisers;
  • 362 to 126 in destroyers; and
  • 248 to 66 in submarines.

Now the Japanese had advantages: naval aviation, as mentioned, and the Long Lance, but quantity has a quality of its own. The Japanese could count, and they knew that in a prolonged struggle they'd be stomped by American and British shipbuilding, so the numbers would always get worse.

And then that doesn't get to the sizes of the merchant marines that could carry supplies and troops to the front, nor the air forces and armies.

The question was whether the suicidally overconfident military government in 1941 looks around and realizes they don't have an opening. In 1941, they could fool themselves into thinking the French were out of it, the British were on the ropes, the Dutch weren't worth worrying about, and the Americans didn't really have skin in the game aside from a quasi-colonial status with the Philippines, so they might be convinced to back down. With the British not distracted, the French with colonies they would fight hard to keep, and the Americans still the same threat, things are different. I suspect they would have swallowed their pride and tried to negotiate a way out.


It's hard to speculate at this, but I think Italy under Mussolini would have carried out Hitler's role, effecting very similar results. Since Germany swore off war, Mussolini would have no trouble taking them over.

One could make the argument that Mussolini was more tactically conservative than Hitler, so blitzkrieg wouldn't have been as much of a thing. This might have meant years of trench warfare instead of a quick takeover of Europe. Heck, in that scenario, Europe might still be at each other's throats in one form or another to this day.

  • $\begingroup$ Thanks, I totally forgot to mention Italy in my question ! I am making the hypothesis that Europe would remain at peace during this period so I edit my question. $\endgroup$ – user53220 Aug 7 '18 at 20:50
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    $\begingroup$ Mussolini's big problem was that the Italian Army was weak. In the last stages of the Battle of France, Italy was ignominiously defeated by the remaining French on the Italian border. Without German support, the invasion of Greece and the attack in North Africa would have been soundly trounced. $\endgroup$ – David Thornley Aug 7 '18 at 20:54
  • $\begingroup$ Ah gotcha :) Makes sense. $\endgroup$ – boxcartenant Aug 7 '18 at 20:59
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    $\begingroup$ Italy tried to invade Greece and failed; the mighty Italian army was driven back into Albania. Germany was forced to intervene, which delayed the attack on the Soviet Union by several crucial months. Overall, Italy was not a net positive addition to the forces of the Axis. $\endgroup$ – AlexP Aug 7 '18 at 21:13

With European powers unoccupied, attacking Perl Harbor would have been a complete and utter suicide for Japan (not like it was much different in our real timeline, but Japan's own leadership would clearly see it).

If Japan would have done it anyways, Britain would certainly join forces with US, and Imperial Japanese Navy would have been severely pressed much earlier in the war. If Britain would send out expeditionary forces as well, Japan may have been defeated within a year.

This, however, would have created an opportunity for Hitler to make his strike, and successful invasion of Britain would be very real. In essence, Japan may have sacrificed itself to allow another Axis power to win.


No Nuclear Weapons, at least not yet

Assuming that Pearl Harbor and much of the rest of the Pacific war went on as others have suggested, one big change would have been at the end. On the one hand, with the US fighting only one big war instead of two, they would have likely finished the war sooner. But on the other hand, the initial motivation for the Manhattan Project was the war against Germany and fear that Germany was working on nuclear weapons - e.g., Einstein's letter.

While the US did end up using the bomb on Japan, that was not the original plan. Without the war in Europe, and with an accelerated timeline for the Pacific war, the Manhattan Project might never have even started, and almost certainly would not have produced usable weapons before the end of the war. That means the end of the war, while sooner, might have involved more American casualties in the final battles. Long-term effects might be even bigger - without a Manhattan Project and Soviet spies, we might have never gotten to MAD and the Cold War could have been quite different.

  • $\begingroup$ Einstein may signed the letter, but it was drafted by Leo Szilard and Eugene Wigner. $\endgroup$ – a4android Aug 8 '18 at 6:20
  • $\begingroup$ @a4android I'm well aware of that. But the issue is the same with all of those people - it was about getting the bomb before Germany did, and about stopping Germany in general. I've read plenty about it - including the fictional The Berlin Project which I highly recommend for a very slight alternate history (Manhattan Project moves faster) that results in dramatic changes, but with a LOT of real physics & history mixed in. $\endgroup$ – manassehkatz Aug 8 '18 at 15:10
  • $\begingroup$ It's that not everybody knows that. Technically it should be called 'the Einstein letter', but that's a minor point. Certainly the German Bomb was the driver. The first phase of its development was in the UK. I'm still surprised the Manhattan Project went ahead. An incredible deployment of manpower & resources. Even Japan had a Bomb project (surprisingly!). Benford would have added to lot of physics & history. Glad of the reminder. With a one-front war WWII would have been over earlier. $\endgroup$ – a4android Aug 9 '18 at 1:58

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