It is widely known that the US Naval base at Pearl Harbor, Hawaii, was attacked in the morning of Sunday, 7th December, 1941 - resulting in the US entering the Second World War (source: History.com).

My question is, how would have the Second World War played out if the Japanese fleet were wiped out, or at the very least seriously crippled, in a freak event en route (e.g. rogue waves, typhoon, meteor strike etc), preventing the raid on Pearl Harbor and wiping out the effectiveness of a significant proportion of the Japanese Imperial fleet?

Note: this question is not about how the Japanese fleet was stopped in this scenario, but about the outcomes were it stopped.

Would the United States still have joined the war?

What would the consequences be for the war in Europe?

  • $\begingroup$ The problem with the question is who could have stopped Japan? UK and China are the most probable but were already struggling at that time. Japan had no real adversary on sea in the Pacific. $\endgroup$
    – Vincent
    May 17, 2015 at 1:41
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    $\begingroup$ Related: The Final Countdown, a movie where a modern aircraft carrier goes back in time to the day before the attack on Pearl Harbor. $\endgroup$
    – Frostfyre
    May 17, 2015 at 1:49
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    $\begingroup$ @Vincent For the purpose of this question, let's assume rogue waves and freak storms sank the entire fleet en route. $\endgroup$
    – Frostfyre
    May 17, 2015 at 1:59
  • $\begingroup$ @Frostfyre I am so going to borrow that, as Vincent makes a good point. $\endgroup$
    – user9671
    May 17, 2015 at 2:02
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    $\begingroup$ @santiago - not worthy of an answer...but one of Japan's downfalls became their lack of trained pilots (a downed zero was a dead pilot...Americans in mustangs and thunderbolts often survived their plane being crippled in a dogfight). Losing all the pilots that were to participate in the Pearl Harbor attack would have been a big set back...they may have been forced more to the battleship tactics, which fail in the face of air superiority. $\endgroup$
    – Twelfth
    May 19, 2015 at 20:05

6 Answers 6


The true effect of the crippling or destruction of the Japanese fleet prior to the attack on Pearl Harbour might have been to swing the balance of power in Japan back to the Imperial Army.

In the 1930's, various factions struggled for supremacy inside Imperial Japan. The "Army" faction saw China and Siberia as the best sources for raw materials that Japan needed to continue existing as an industrial nation, while the "Navy" faction saw the British, French, Dutch and American empires and possessions as the proper place to gain these raw materials.

The Army argument was that their preferred plan involved less risk (a divided and warring China and a more or less exhausted Soviet Union post civil war), and the materials were fairly close in geographical terms, allowing the Empire to easily control these resources. The counter argument was that they were relatively undeveloped and would require huge investments and a lot of time to develop.

The Navy argument was that the Empires in the East had already developed the resources and had pools of trained manpower to extract these resources. There would be no "costs" to develop the resource base, and it was also thought most of the people there would actively cooperate if their white Imperial overlords were displaced. (no one seems to have thought these people would object to having their white overlords replaced by Japanese overlords...)

The Army lost the argument in 1937 when the Russians defeated the Japanese army in the Battles of Khalkhyn Gol, essentially closing off the Siberian resources argument. The Imperial Navy needed time to prepare for its multi faceted strategy, but their hand was essentially forced with the American embargo of oil and steel.

If the Imperial fleet had not been able to deliver its blow against the Americans, and this was known early enough to call off the remaining attacks on the European Imperial possessions in Asia, then the Army probably would have been able to muster the support for a renewal of their fight against the Russians and expanded operations in China; changing the completion of the war entirely (the German invasion of Russia would not have been opposed by an extra 25 divisions rushed from Siberia in the winter of 1941, for example).

Beyond that, the calculus become very involved, so alt histories written from that point could have innumerable outcomes.

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    $\begingroup$ Good point with the politics. Not quite convinced the Japanese would have jumped that way, but a an attack in the east simultaneous with Barbarossa would have kept the Siberian divisions, Zhukov, and significant part of Russian air force in the east. If the US also stayed out of the war that would probably meant the Russians losing in Leningrad, Moscow, and Stalingrad. And unable to retreat behind the Ural. With the Soviet Union out of the war Germany would have been able to focus dealing with the British and the Japanese (and Germans!) would have had access to Soviet oil and steel. $\endgroup$ May 18, 2015 at 22:06
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    $\begingroup$ Since there are so many ways this could have played out, I suspect that there can never be a real consensus as to the "correct" answer. After all, the Imperial Navy might still have been able to go ahead with their plan absent Pearl Harbour since the key part of their argument; "resources were already developed and manpower already available" would be hard to trump for a hard pressed Imperial economy already suffering from the embargoes. $\endgroup$
    – Thucydides
    May 18, 2015 at 22:53
  • $\begingroup$ Yup, that was essentially my thinking. $\endgroup$ May 19, 2015 at 0:14
  • $\begingroup$ The problem with the this idea is that while Siberia was known to have the potential for resources, it didn't have two critical ones that the Japanese absolutely needed: oil and rubber. The Western Siberian oil fields were only discovered in the 1970s, so wouldn't have influenced a decision decades earlier, and the Russian fields at the time were, at the closest, in the Urals. And, of course, no rubber plantations. The Japanese had to go south, and that made war with the US almost inevitable. $\endgroup$ Dec 21, 2017 at 19:29

The attack on Pearl Harbor started on November 26, 1941, with the departure of the Striking Force from Japan. It was just one of many operations planned for December 7, 1941, but it was the keystone: the entire Japanese battle plan depended on knocking the American Pacific Fleet out of action. This gives two major possibilities for alternate courses of history:

First option

The fleet is wiped out early, and this fact is communicated back to the Japanese high command. The rest of the operations are canceled. This doesn't mean Japan stays out of the war, though: the Allied iron, steel, and oil embargos were crippling to Japanese industry. It's likely that a new Pearl Harbor-style attack would take place within six months.

However, this delay could turn out to be a fatal error for Japan. The Essex-class and Independence-class carriers were already under construction by December 1941. With six of Japan's aircraft carriers sunk, Japan has only six fleet carriers facing five American fleet carriers, and the American carriers are 50% larger than the Japanese carriers. This won't deter the Japanese -- their naval doctrine is based around decisive combat between battleships -- but combat realities are different, and the extra carrier force available early in the war could result in a much shorter Pacific campaign.

Second option

The fleet is wiped out late, on the eve of the attack, or so abruptly it can't communicate back to Japan. With so many plans in motion, they have no option but to continue. The Pacific War starts on schedule, but with no surprise attack on Pearl Harbor, the Japanese declaration of war arrives before the attacks, and there is no Day of Infamy.

The early stages of this war would go much as they did in the original timeline. The American plan will probably adhere more closely to War Plan Orange, and there may be some battleship-vs-battleship fights that otherwise wouldn't have happened, but the key elements for American victory (submarine and carrier construction in particular) were set in motion long before the start of the war.

The likely difference will come at the end of the war. With less motivation to demand an unconditional surrender, it's possible that the Allies would be willing to accept a negotiated surrender that involves Japan returning to its pre-Sino-Japanese War borders, rather than unconditional surrender and occupation, which could shorten the war considerably. Whether Japan would be willing to accept is anybody's guess.

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    $\begingroup$ Kudos on pointing out that the embargos made the war inevitable, Japan needed Indonesia, many people forget that. I don't think the Japanese would have delayed starting the war, though. As you pointed out it wouldn't have helped them. The Japanese were well aware of the difference in relative industrial capacity and the effects of the embargo making their strong pre-war position weaker. $\endgroup$ May 18, 2015 at 12:02

The question you ask is related to various conspiracy theories.

Did the US government want to get involved in WWII?

One could make a good case that the US government was already involved in the war. Lend-lease, Neutrality Patrol, they clearly took sides in the war in Europe even without a formal declaration of war. The Pearl Harbour attack galvanized the public opinion to get even more involved and to get the country onto a war footing.

The conspiracy theorists claim that the government deliberately didn't warn Pearl Harbour to get their new Maine Incident. I don't believe this, but maybe without the Pearl Harbour strike the isolationist sentiment would have prevailed.

What else happened around that date?

Japan had many coordinated operations in the Pacific theater. If not for Pearl Harbour, might the attack on the Phillipines the next day have had the same result regarding public opinion?

Day of Infamy

Without the strike at Pearl, the fitst Japanese attack would have come closely after the declaration of war. This might have taken some of the rancor out of the war -- or not, considering what happened at Bataan. Perhaps it would have been Europe even more first?

Extra battleships

Would the surviving battleships have affected the Pacific war? Nobody knows. The US might have tried to use them, only to have them sunk by carrier planes. Or they could have been used as anti-air/anti-surface escorts for carrier groups.

Axis declaration of war

Again, nobody knows if that would have happened. The German declaration of war resulted in some submarine warfare on the East Coast, but Japan didn't reciprocate by going after Russia.

Summarized, there might have been a small likelihood of a peace settlement in the Pacific, which gave the Philippines and the rest to Japan while the US concentrated on Europe. And a small likelihood of no Axis declaration of war, which could have led to Pacific first. More likely, nothing much changes.


Since nobody has, I'll cover the European consequences.

Japan launched many simultaneous attacks that day, but the only other one against the US was in the Philippines and this happened seven hours after Pearl Harbor. There was time to call it off. If the attack went off as planned the US would be dragged into war with Japan. But if it didn't, if the attack on the Philippines was cancelled, the US entry into war with Japan would be delayed.

Either way, the US entry into the European War would have been delayed at a critical point in the war in Europe.

On Dec 11th, 1941 Hitler went against the advice of his staff (something he would do again and again) and declared war on the United States. It's one of Hitler's greatest blunders and one of the war's greatest mysteries why he decided to do it. Without a smashing Japanse victory at Pearl Harbor this would not have happened.

War between Germany and the US was by no means inevitable. The US was still neutral, and it was still building up its military. An attack by Japan gave the US even less incentive to start a two-front war. As for Germany, they were mired in a battle with the Soviet Union and the Battle of the Atlantic. Military logic said opening an new front was madness.

Without the spectacular victory of Pearl Harbor to excite Hitler's imagination, it's likely cooler heads would have prevailed. Instead, the Germans would have waited for the outcome of the inevitable massive naval battle in the Philippines planned for by both the Japanese (Kantai Kessen) and the US (War Plan Orange). They would have negotiated with Japan to guarantee Japan declares war on the Soviets.

Without the US as a belligerent in Europe, supplies from the US to the Allies would be reduced. The US would need to keep the veneer of neutrality and continue the awkward lend-lease arrangement which restricted the volume, speed, and types of material they could send to the Allies. As a neutral the US could not conduct any combat operations against the European Axis. Lacking a "Germany First" agreement with the Allies it's probable the US would have held back more of their material to fight the Japanese rather than lease them to the British and Soviets.

The impact of the Tizard Mission would be reduced. In Sept 1940, in order to circumvent US neutrality provisions, Britain simply handed the US many fantastic new technologies such as the cavity magnetron necessary to produce compact radar sets, the variable-timed fuse for air burst artillery shells, a jet engine, rockets, superchargers, gyroscopic gunsights, submarine detection devices, self-sealing fuel tanks, and plastic explosives. They hoped the US would develop these, build them with their massive industrial capability, and then Britain could buy them back. In our alternative timeline there would be no US aircraft equipped with these wonder weapons to fight the Germans, particularly U-Boats. The US would have been more interested in putting them to good use against the Japanese rather than lease their best weapons to the British.

In North Africa this means no US tanks to resupply the British Army. No great victory at El Alamein where US tanks made up half the British army's force (M3 Grants, M4 Shermans, and M3 Honeys). No Operation Torch to simultaneously open a second front in North Africa. Without the US in the war the British will be very hard pressed to hold on to Egypt and the Middle East.

Over the skies of Germany this means no US strategic bombing of Germany. The US contributed about half the total damage to Germany, now Britain would have to go it alone. Furthermore, the "round the clock" bombing campaign would not have happened, Britain preferred to reduce losses by bombing at night, allowing the Germans to freely rebuild and move material around during the day. German industry would take less of a beating, and less of its military would be required in the defense of the Reich allowing them to throw more at the Soviets at a critical moment of the Eastern Campaign.

In the Battle Of The Atlantic, the US is spared the slaughter of the Second Happy Time, but the British have to go it alone. Without US aircraft and destroyers bolstering the escorts, the Germans would have continued to successfully exploit the GIUK air gap. Without US industrial help, new British invented anti-submarine technologies would have been slower to come online and less would be available. Even with full US support the battle was nearly lost. Without it, it's likely Britain would have been strangled in May 1943.

On the Eastern Front, US supplies to the Soviet Union will also be reduced. While US tanks and airplanes were generally considered inferior by the Soviets, they were still better than nothing and could be used by rear and training units to free up better equipment for front line units. What would be sorely missed is US logistical support in the form of trucks, trains, industrial machines, and raw material to rebuild the Soviet industrial base. Here is an exhaustive list. Without this support the Soviets would have less capacity to rebound again and again from crushing defeats in the field.

1942 was already a bad year for the British and Soviets, without the German declaration of war against the US it would have been much worse.


If the Japanese had never bombed Pearl Harbor, there would be a much larger possibility that the US would have never entered the fighting. While we might've been forced to fight Japan, I do not believe the US would have sent men to the European Theater. If this had happened, the Axis powers not only would've defeated Britain, North Africa would've never been freed, Italy would have stayed a friend to Germany, more and more Jews would've been killed in concentration camps. There are other possibilities that I cannot answer but must bring up. Russia might've never been attacked by Germany, Germany might have gotten Hiesenburg to developed the nuclear bomb before the US did, and the Zimmerman Telegraph might've never been intercepted and the US could've been attacked by Mexico.And obviously, Hitler would still be alive and leading an empire to world domination.

  • $\begingroup$ I thought the Zimmerman Telegraph was World War One. $\endgroup$
    – user24353
    Dec 23, 2015 at 4:31
  • $\begingroup$ @user24353 It was. This answer mixes up the two wars. $\endgroup$
    – Schwern
    May 5, 2016 at 21:06

The Japanese attacked America because they knew it was inevitable that America would join the war and they wanted to cripple a future enemy before they could strike back.

If the attack never happened, America would still have joined the war so I doubt the outcome would be all that different.


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