Kantai Kessen, the Japanese naval strategy for a Pacific war, amounted to (simplified) "The American fleet will cross the Pacific to attack Japan. At that time, we will engage and defeat them."

Creating a battle plan that depends on the enemy's cooperation is a beginner's mistake, not something you'd expect from a senior naval strategist. The Japanese must have had some reason to believe that an attack was the only viable option for the Americans. What was that reason?

  • As I am personally interested in WW2, personally the initial commander in Chief Of Japanese Navy who died or was killed in 1943, Isoroku Yamamoto's first plan was to attack enormously America and he considered because of his knowledge and experiment of stay in America ( he went to Harvard ), knowing the huge gap of the difference of productivity between the U.S and the then Imperial Japan,
    – user12387
    Commented Aug 10, 2015 at 10:44
  • only promised the Imperial Navy would confront with the that of U.S with its full might at least within a year and half, and his quote remains as If we go to war, we will destroy the U.S army before we see the smoke of the battleships, and could you elaborate more what is the relationship between the term Kantai Kessen and your next assertion? I am not so sure with sorry.
    – user12387
    Commented Aug 10, 2015 at 10:54
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    I am afraid to say like this, when the English Wiki tries to describe anything about issues regarding East Asian culture/military/history etc etc, it looks always full of doubtful lines. For example only 2 general in the then Japanese Imperial Army was influenced by Alfred Thayer Mahan in the link at the questioner's question, my search says the Imperial Army was more influenced by British than Americans. I am sorry to say like this, but I wish you will meet good resources. Thank you.
    – user12387
    Commented Aug 10, 2015 at 14:24
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    The reason is, for example, when I hear as a native speaker the questioner's opening Kantai Kessen, the Japanese naval strategy for a Pacific war, due to the simple semantic reason that the terms Kantai Kessen is a one time battle. You need the word Shugi which is almost same with Motto to make it sound as a "strategy". And I continued to read later on checking or comparing important words with these of Japanese, and I knew about Osami Nagano ( who is famous for having been killed by Samurai sword because of the factional dispute ) and I first time knew oh he did such thing..etc etc )
    – user12387
    Commented Aug 10, 2015 at 22:29
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    @KentaroTomono Your ability to translate native Japanese documents and zeal for WWII history would be most appreciated on both the English Wikipedia and here. Focus your energies towards providing answers. Extensive comments are discouraged here, answers are the meat of Stack Exchange. If our understanding of Kantai Kessen is flawed due to a bad translation, that would make a good answer.
    – Schwern
    Commented Aug 11, 2015 at 1:43

5 Answers 5


Many people seem to be confused that this was a plan developed during or just prior to WWII to defend the home islands, this is not true. Kantai Kessen was developed and adopted after the Russo-Japanese war (1904-1905) and well before the US entered WWII (1941). With that in mind, answers must take into account the interwar situation and mindsets of the 1910s, 20s and 30s. Anything from Pearl Harbor onward does not apply; by then the doctrine had long since been adopted and debated by Japanese naval leadership.

It's too simplistic to say the Japanese plan assumed an attack on Japan, but it did assume they could draw the US fleet deep into the Japanese defensive perimeter, far from supply, repair, fuel and land-based airpower, and destroy it in one pitched battle. This was a good plan. The US would have to sortie their fleet to defend their far flung Pacific empire, most notably the Philippines. War Plan Orange, the US pre-war plan to deal with Japan, was exactly that.

Japanese thinking was heavily influenced by their victory at the Battle of Tsushima. A Russian fleet, worn out after traversing half the globe, was destroyed near the home islands in one decisive battle.

And the Japanese needed a decisive battle. The Japanese knew they could not outproduce the US. They needed to deliver a crushing blow quickly, destroy America's ability to project power as they did in the Russo-Japanese war, and negotiate a favorable peace. This is a case of wishful thinking, but it was also the only plausible path to victory.

Things did not go as planned for the Japanese; they went too well. The quick subduing of Allied territory and the destruction of the US Pacific fleet at Pearl Harbor meant there was no American empire left to defend and no fleet to do it. This changed the war from a quick, honorable, decisive victory, which the Japanese could win (or at least negotiate favorably), into a long battle of attrition which they could not.

The IJN had a tendency to write battle plans which were overconfident. They assumed the cooperation of the enemy and belittled their abilities. In planning the Battle Of Midway, the Japanese commanders stated where US carriers would be (far away in the Aleutians) and how they would react (by rushing to Midway). Midway was supposed to be the decisive battle the IJN was seeking, and it would be, but not the way they thought.

Kantai Kessen did work against the British, on a smaller scale, when Force Z was destroyed on their way to defend Malaya.

  • Please do not take it as an "envy". But your saying " but it did assume they could draw the US fleet deep into the Japanese defensive perimeter, far from supply, repair, fuel and land-based airpower, and destroy it in one pitched battle." seems to be completely different that of mine. Upon the JIA received the Doolittle Raid,link, the then Emperor summoned Prince Naruhiko Higashikuni link
    – user12387
    Commented Aug 13, 2015 at 5:46
  • And the above mentioned prince replied "Considering our defensive system, we are very vulnerable to the U.S airstrikes, thus we need build construction system to prevent it", which, in its culmination, forced the JIA to think about the Operation Midway...........
    – user12387
    Commented Aug 13, 2015 at 5:54
  • So I don't personally think the Japanese Imperial Army did not presume the "decisive attack from the enemy in the nearest periphery". Or rather it would be contrary to me.
    – user12387
    Commented Aug 13, 2015 at 5:56
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    @KentaroTomono Yes, by 1942 the plan was acknowledged by some to be outdated and flawed due to the increased range and power of aircraft and submarines. The Doolittle Raid hammered that point home (even if they hammer was very small). However, as I mentioned in my opening paragraph, the question is why Kantai Kessen was adopted by the Japanese. It was adopted decades before the Doolittle Raid so the raid is irrelevant to the question. If you have something from the 1920s or 30s that would be relevant.
    – Schwern
    Commented Aug 13, 2015 at 6:03
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    I am sorry it will be a bit intricate to elaborate furthermore. "Kantai Kessen Shugi", which was almost a "belief" among many Japanese, DID exclude the assumption the U.S would come far from its homeland...........
    – user12387
    Commented Aug 13, 2015 at 6:21

The Japanese navy had a fundamental misunderstanding of the American navy, in large part because of its experience with other, European navies such as those of Russia and Britain. And perhaps they were confused by America's War Plan Orange," which preached similar doctrine, but was more "honored in the breach than the observance."

In the 1905 war with Russia, that country had a (Far East) naval base at Port Arthur, Manchuria. The Japanese won the naval war by defeating the Russian fleet there, and then winning a second battle at Tsushima Straits against a reinforcing fleet headed to Port Arthur, and took the most obvious route there. Likewise, the Japanese destroyed a British task force that was detailed to defend Singapore and Malaysia.

The Japanese thinking had some merit for the Japanese Empire up to about 1920, which included the Home Islands, Iwo Jima, Okinawa, Korea, Formosa, and a bit more. But the 1920s and 1930s militarization of the islands (Marianas, Caroline, and Marshals) acquired in the South Pacific Mandate after World War II (which specified de militarization) made it very dangerous to for the Americans to leave these islands in the rear during a "main force" strike. Also, during the 1930s, "dissidents" in both the American and Japanese navies opined that advances in air and submarine warfare had made such "main force" naval tactics obsolete. The difference was that America eventually allowed its dissidents to prevail, and Japan didn't.

And when World War II began, Japan began expanding far beyond what original plans envisioned, including to Papua New Guinea in the south, Midway Island to the East, and the Aleutian Islands in the Northeast. With a huge bubble of that sort, the Americans found through trial and error that a more expeditious strategy than its original Plan Orange was to "pick off" Japanese forces along the perimeter (as they did at Coral Sea, Midway, and the Aleutians), instead of trying to fight the main Japanese navy near the Home islands. Eventually, the Americans did "get there," but only after the Japanese navy had been greatly weakened by attrition.

In sports terms, the Americans used a "full court press" over the whole Pacific, fighting a series of "duels" that would deplete Japanese naval power at a faster rate than American naval power. In this regard, they were using an "attrition" strategy like that of U.S. Grant against Robert E. Lee. (During the course of the war, the Americans outbuilt the Japanese 3 to 1, and that's not counting the material they used against Hitler.) The Japanese were hoping that the Americans would send their fleets against the Japanese fleet for one all out battle after another, and that the Japanese would destroy three or four American fleets in the process without losing her own.

The Americans preferred to bleed the Japanese to death by "trading shots." Coral Sea, one Japanese carrier sunk, two put out of action, versus one American carrier sunk, one damaged (the Yorktown, repaired for the Midway battle in one weekend). At Midway, the Americans sank four carriers while losing one, but that hardly mattered; a four to three "kill" ratio would have been sufficient. Basically, the Japanese would have had to sink all three American carriers with the loss of no more than one to maintain the 1 to 3 parity dictated by the countries' relative productions. Anything "worse" (e.g. two Japanese carriers lost for three Americans), and the Americans would win.

Put another way, the Japanese (reasonably) believed that the Americans would follow a "script" laid down by the Russians, British, and the Americans themselves. The Russian navy at Tsushima in 1905 followed essentially the same tactics after the surprise attack at Port Arthur as before (even to the point of using the route the Japanese expected them to). This British didn't seem to care that they could "lose the war in one afternoon" at Jutland in 1916. But the Americans departed from a script of one "all or nothing" battle when their numerical superiority could make the "law of averages" work for them in numerous "knife fights." Give credit to Admirals Halsey, Nimitz, and others for that.

  • Unless the American public decided that losing that may people was not worth it. I don't know if the public would have allowed a war with a 50% more loss of life then the Japanese to go on for a long time. Commented Aug 9, 2015 at 21:49
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    @IanRingrose: In his 1943 State of the Union Speech, President Franklin D. Roosevelt reported that American planes were shooting down Japanese planes at a rate of 4 to 1. Given American anger over the "sneak attack" at Pearl Harbor, that was more than acceptable. The Americans (probably) would have accepted 500,000 dead at the expense of 2 million dead Japanese.
    – Tom Au
    Commented Aug 9, 2015 at 22:11
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    The problem with this answer is Kantai Kessen was developed in the 1920s and 30s. The island hopping and broad front war of attrition US battle plan you describe didn't develop until after Pearl Harbor, and only then to meet the new reality after losing their Pacific battle fleet. On Dec 6th, 1941, War Plan Orange was the plan; island strong points (Wake, Guam, Corrigador) were to be defended until the fleet could arrive; the carriers were only coincidentally not at Pearl Harbor on Dec 7th. I would need citations otherwise.
    – Schwern
    Commented Aug 10, 2015 at 3:41
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    @Schwern Good point about the carriers. Commented Aug 10, 2015 at 5:14
  • @TomAu, but would the Americans have accepted 4 million dead at the expense of 2 million dead Japanese? (The USA would still been able to win the war at that rate justing looking at the numbers.) Commented Aug 10, 2015 at 9:31

Kindly allow me to update completely.

As a starter, I being a native speaker, kindly be reminded it would sound very strange when the OP says "Kantai Kessen, the Japanese naval strategy for a Pacific war" ( Excluding the fact that the Wiki was updated by someone ). The reason is, simply, in term of the usage of the word. Kantai Kessen simply denotes the one time battle. If you tell me the reason why, then I will have to escape to say, "Please learn Japanese"....... Had I been heard as a Kantai Kessen Shugi, since the last word means kind of like a motto or, more like, considering the atmosphere at that time in my assumption, it would be more like a "belief or faith" ( in terms of like religions ) into large scale battleship classes ( such as Yamato class ) using the main weapons in order to gain the "decisive win" as the Wiki says also.

So in the perspective of gaining "decisive wins or victories", the term "Kantai Kessen" can be applied to any battle, from Midway to Leyte to even Yamato's de facto Banzai attack into Okinawa.

Now I am afraid to say, the OP's question is not so well understandable to me.

I would like to assume the OP has some doubt about the below line of the Wiki.

This would limit the time the American fleet could operate in the western Pacific and force them to commit to a single major battle, a battle which Japan could win decisively as they had at the Battle of Tsushima.[5]

Now regarding this issue, I found a site which is in Japanese. So if you have doubt in your mind that mine quote and its corresponding translation would be wrong, please go to Japanese Language site for the check.

This site explains,

( Why does this site allow the citation of Chinese characters?? ) --> So that I can not cite the original text.

Granted the above site explains, the top officers' strategy at the initial stage was

1 Strike and push eastward to "destroy" or gain the "decisive victory" in the pacific sea.

2 Win at any cost and destroy anywhere in the Pacific Sea the U.S navy. This thought itself became the object of the war. ( = meaning, or suggesting, the Imperial Japanese Navy did not have "logical" strategies in their minds.

And this site which is fortunately in English, could become a very important answer to the questioner.

Zettai Kokubo Ken, Absolute National Defense Zone, which was drafted around early 1943 when the tide turned unfavorably to the Japanese Imperial Army, set the literally "to set the definite lines or perimeters into which American army should not have been allowed" ( in order to evade the bombardment by the U.S airforce on the homeisland.( For example, let us examine the Battle Of Iwo Jima, which was one of the most fiercest fights between the JPA and the U.S during the pacific war. Almost everybody, around 18,000 men died. The U.S casualty was also hideous, around 7,000 men died. The reason why the JPA fought so hard? Simply in order not for the U.S to set up the airbase for their bombardment )).

So that the O.P's question, was contrary to thoughts of the then high ranking officers of JPA. I could be able to say, the JPA actually had no systematic plan in its principle after all.

I hope I could have answered to the questioner's question somehow.

Have a happy day.

  • 2
    I think you misread the OP's question, as I initially did, to apply to the reality of 1944. Kantai Kessen is a pre-war Japanese plan of attack, not a plan to defend the home islands.
    – Schwern
    Commented Aug 10, 2015 at 3:42
  • Please clarify the reason of the downvote, If I shortly summarize, the word "Kessen" only denotes "the decisive battle". You will understand the meaning of it if you check it in the dictionary. So throughout WW2, everywhere the "Kessen=the decsive battle" occured, from even Papua Nugenea to Saipan to Io island to Yamato's Banzai attack. Kantai only denotes the "decisive battle" be conducted by the battleships. I came here only because I thought I was summoned since I got upvoted, well, but well, I am not welcomed here. Have a nice day.
    – user12387
    Commented Aug 10, 2015 at 4:19
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    I am the downvoter. Please do not take it to mean you're not welcome. Voting is about the quality of the answer and how well it answers the original question. I downvoted because while your answer may contain true statements, it does not address the question. Your answer and comments are about vocabulary, general Imperial Japanese attitude, and defending the home islands. The question is about the particular Kantai Kessen plan developed by Japan pre-WWII to defeat the US navy.
    – Schwern
    Commented Aug 10, 2015 at 4:29
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    You are missing the point. The literal meaning of "Kantai Kessen" is of little significance; it could have been called "Decissive battle doctrine" or "Plan X". So, you should not answer based in the name, but in the plan described by the link. Japanese defense of the islands obviously is not part of that, since the plan was that the USA would be defeated far away from it (in fact, they expected to destroy them either at Pearl Harbour or Midway). The "Japanese do not surrender" motto is pointless, because Kentai Kessen was to be a winning strategy.
    – SJuan76
    Commented Aug 10, 2015 at 7:40
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    Yes, so as I made a comment at the questioner's place the then Martial of the IJN wanted the "decisive victory far away from the home island"..............................................................................................................................................
    – user12387
    Commented Aug 10, 2015 at 23:28

"Creating a battle plan that depends on the enemy's cooperation is a beginner's mistake."

They did not have any shortage of such mistakes.

They fought Midway with the expectation that the US carriers wouldn't show up until they took the island. That's why their entire fleet was armed with land attack armaments at the time the USN showed up, and Nagumo ended up having to waste 30 minutes rearming his bombers, costing him the battle.

They fought Guadalcanal because they expected Nimitz to only send 2,000 men and planned accordingly. Ichiki's initial detachment consisted of less than 1,000 men, and despite being repulsed, they sent Kawaguchi's Brigade of 3,500. Only after that was repulsed did they finally decide to send a whole Division. To compare, Nimitz's initial force was the first Marine Division at 10,000, with actual heavy weaponry and supplies, something the Japanese couldn't transport onto Guadalcanal.

They were utterly unprepared for Saipan (The entire Marianas had only 50 land-based aircraft then) because they hoped the United States would attack somewhere else instead. Admiral Ozawa was the only one that thought otherwise (which is why he even had a battle plan drawn out that resulted in the battle of the Philippine Sea).

One myth is that the Japanese only lacked material. They lacked far more than that, especially in the department of employed strategists. It's enough to write two books on, so I'd recommend you pick up a full biography of Tsuji Masanobu, and take special note on what kind of education he received and how much battle experience he had before starting to command entire armies by proxy (spoiler: near 0).

  • This doesn't appear to answer the question. It's true the Japanese often made the mistake of expecting the US to conform to their plans. But this doesn't answer why they expected the US would attack the home islands.
    – Schwern
    Commented Aug 14, 2016 at 6:26

The japanese was in their best military moment. Great army, great expansion, victory over victory. The famous "banzai", even their own government believe in their invencibility. The UK was withdrawing, China invaded, Holland asiatic islands invaded, Only Soviet Union could stop them.

In addition, Japanese Navy was in their best moment, really impressive even better than german navy. For the Japanese, USA had the only navy that could defy his expansions plan. Pearl harbour was a careful plan in order to give USA a heavy knock in order to prevent Americans any danger in their desires to make a great empire. However, the knock ended in great fail because the US carriers werent there. The Surprise Japanese attack didnt have the effect that they expected and provocked "the wake of the US Giant navy" the only enemy with the power to defeat them was awake.

  • 6
    This doesn't address the question that was asked. You should remember to read the whole question (and any existing answers).
    – Steve Bird
    Commented Aug 13, 2016 at 23:59
  • What Im saying is that they tried to defeat USA with one knock but the consecuences were their total defeat. They that they were invencible but was far from reality the incredible US power ended with their leyend of thier invencibility. Commented Aug 14, 2016 at 21:31
  • They were teaching in their homeland that they were the elite warriors that no-one can defeat them. USA gave them a big lesson of reality. The attack in their homeland .was a matter of time because they have a giant enemy really angry. Commented Aug 14, 2016 at 21:34

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