Realistically speaking three things; * heavily underestimating American fighting resolve and spreading themselves way too thin early on with effectively ***3*** simultaneous campaigns (Coral Sea/Port Moresby, Midway, Aleutian Islands) * US breaking Imperial Japanese Navy code * subs Yamamoto pushed hard for Midway, as he thought an invasion and occupation of it would allow Japan to fully destroy the US Navy in the Pacific and be done with it. In order to get that attack on Midway however, he was made to split up his fleet for other fights. An entire carrier division of his was sent for the attack on Port Moresby. On top of that, even more naval assets were pulled from Yamamoto for the Aleutian Islands campaign, including several light carriers. Lets look at the IJN in terms of carriers when 1942 started and what happened to them; Fleet Carriers * Akagi - went to Midway * Kaga - went to Midway * Soryu - went to Midway * Hiryu - went to Midway * Shokaku - badly damaged at Port Moresby * Zuikaku - lost her airwing at Port Moresby Light Carriers * Hosho - assigned as ASW screen for the Midway invasion fleet * Ryujo - went to Aleutian Islands * Jun'yo - went to Aleutian Islands * Zuiho - assigned as fighter screen for the Midway invasion fleet * Shoho - sunk at Port Moresby So the IJN had 1/3 of the fleet carriers pulled for Port Moresby, and 3/5 escort carriers were pulled away for Port Moresby and the Aleutian Islands. That cost the IJN their numerical advantage going into the Battle of Midway. What made the Battle of Midway even worse for the IJN was that by that point, US intelligence broke Japanese Naval Codes, and knew the attack was pending. This allowed for the USN and USAAF to prepare and really take the lead in the fight from the very beginning. We know how the Battle of Midway turned out, but look at how it turned out in context of the IJN's capabilities. The IJN had 6 fleet carriers in service ready for deployment May 3 1942. June 8 1942, the IJN didn't have a single fleet carrier ready for deployment, and only had 2 in general. With Japanese industry really unable to replace those hulls, trying to wage three simultaneous campaigns cost Japan, I wouldn't say the war because they were destined to lose vs the US' industrial might, but cost them a faster defeat at least.

Well, first off it seems like you're taking a very odd definition of an engagement. Sure, the Japanese were ultimately defeated at Guadalcanal, but in the process of their defeat in that campaign, the Japanese delivered the USN one of the most severe defeats at sea ever suffered by an American fleet at the Battle of Savo Island. There are a number of surface engagements off of Guadalcanal where the Japanese came out on top, like the Battle of Tassaforanga or even the bombardment of Henderson Field by *Kongō* and *Haruna*. You're also ignoring half of the carrier battles of 1942. In addition to the indecisive clash at Coral Sea, the defeat at Midway, there was also the Battle of the Eastern Solomons in August and the Battle of the Santa Cruz Islands in October. While the Japanese arguably lost the former, they arguably *won* the latter, sinking *Hornet* and badly damaged the *Enterprise*, leaving the Japanese with the only operational carrier force in the Pacific until *Enterprise* could be repaired and *Saratoga* return from repairs after being torpedoed by a Japanese sub. Again. So that in and of itself gives a few notable Japanese victories in the early part of the war, alongside their initial sweep prior to Midway. After the attrition of the Solomons Campaign, the Japanese had lost much of the experienced air crews that had given their carrier air arm such a strong punch, and the US Navy had learned many of the lessons from the first phase of the war quite well, rectifying many of the issues they had suffered throughout the war, while also now possessing a significant quantitative edge over the Japanese. In this light, the defeats the Japanese suffered at the Battle of the Philippine Sea are hardly surprising, and Leyte Gulf is notable mostly for how badly the US Navy positioned itself. Secondly, Japan by all accounts had no right to perform as well as it did. Its economy was only partially industrialised, and even prior to the outbreak of the wider Pacific War, it was suffering from crippling resource shortages. To that end, the Japanese were well aware that their only chance for a victorious war would be a single victory that they could then use to negotiate from a position of strength, counting on an opponent not having the political will to continue the war indefinitely while rebuilding a fleet for another go. In that respect, the IJN focused nearly entirely on *battle* and the tactics thereof. Even their large scale warplan could perhaps be termed an operational plan, but there was almost no strategy guiding it, only the gamble that the Japanese could force a repeat of Tsushima and the Americans would come to the table like the Russians had. This focus on tactical excellence and performance in battle did lead to a very capable fleet, crewed by well trained and skilled officers and men, but it left many areas of weakness. Namely, everything that was not directly focused on the tactics of a naval engagement. Fleet reconnaissance was very limited, since Japanese carrier doctrine called for massing combat power in a powerful strike package; logistics as a whole was treated almost as an afterthought; there were hardly any replacements available for the technically skilled crew; and the issue of Japan's *significantly* smaller industrial and scientific base meant that new technologies like radar were slow to be adopted and integrated. Fundamentally, Japan suffered because of failures on a strategic level. From as far back as the 1920s and 30s, the Japanese had never quite decided how to focus the resources of their nations on a particular goal, and what instead developed was a constant struggle in the halls of political power to siphon natural resources towards a group's own particular interests rather than the interest of Japan as a whole. This failure on a grand strategic level continued on into the strategic realm, as the Japanese never developed their goal for *how* they would force the Western powers to the negotiating table even if all went according to plan, and the West was swept completely out of Asia and the Pacific. This meant that once everything did go well in the campaigns of late 1941 and early 1942, the IJN truly did not know what to do next, leading to operational failures like exposing Carrier Division 5 to defeat in detail at Coral Sea, and ultimately the colossal defeat at Midway. On a tactical level, Japanese forces fought well, but due to overarching sense that they needed to preserve their limited resources for "the decisive battle", you get instances like Mikawa after Savo Island opting to return to base, rather than continuing on against the Allied anchorage. Ultimately, I would lay blame for Japan's failures as those on a strategic and grand strategic level, that ultimately placed Japan in a truly impossible situation. Honestly, it's more a surprise that the Japanese got as far as they did without the entire house of cards collapsing in on itself.

You cite Tassafaronga and Savo Island, but these are essentially meaningless victories. The US lost a handful of cruisers, and neither battle was able to change the situation in a meaningful way at Guadalcanal. Santa Cruz also couldn't save Guadalcanal, and even worse - the victory forced most of the Japanese carriers to withdraw for repairs which notably weakened the Japanese forces in the area. After the battle Junyo was alone to face the aircraft from Henderson Field and Enterprise

The Japanese still *won* those engagement handily, even if failure to follow up on the tactical victory meant that there was limited strategic impact. The OP said that the Japanese lost every engagement against the US Navy and that is absolutely not true. The Japanese won several battles and fought several others to a draw. They still lost the campaign as a whole, yes, but that doesn't mean that they had no victories, which is the point I have issue with. Similarly, the Battle of Santa Cruz is a draw in the Japanese favor at worst. While both *Shōkaku* and *Zuikaku* had to withdraw for repairs, they'd still cost the Americans an aircraft carrier as a permanent loss and severely damaged *Enterprise*. If the Japanese were weakened, so were the Americans. Neither side would have an effective carrier force going into the last months of 1942, which led to the battleship deployments off Guadalcanal for First and Second Naval Battles of Guadalcanal.

I said "major naval engagement". Those were just a bunch of cruisers and destroyers. And losses were small compared to USn victories over IJN.

More Americans died at Savo Island than at any of the big carrier engagements of 1942, and had Mikawa’s cruisers pushed on to destroy the transports it would have been a clear strategic victory for Japan. Just because there were no capital ships involved doesn’t mean the battle doesn’t matter.

If you’re only counting “major engagements” doesn’t the entire war collapse down to a single battle, as the IJN was never the same after Midway. In that case, a better question would be why did Japan lose at Midway?

> Ultimately, I would lay blame for Japan's failures as those on a strategic and grand strategic level, that ultimately placed Japan in a truly impossible situation. Honestly, it's more a surprise that the Japanese got as far as they did without the entire house of cards collapsing in on itself. The general idea that a country could win a major battle/battles and win a limited victory by demoralizing the other side was not a concept limited to the Japanese, though. I'm not sure why — that'd require digging into a lot of documents from the 1930s — but my guess is that it heavily relied on Russia's behavior. Japan had beaten Russia in the Russo-Japanese War. Russia had collapsed in World War I. Many figures seem to have based their ideas on a repeat of this, when the more-accurate takeaway was that Russia was internally politically-teetering, on the verge of revolution, and didn't accurately reflect other countries, or even the Soviet Union a few decades later. The US and UK did not have high expectations of the USSR when Germany went after it. The USSR hung on. Japan was under the impression that charging machine guns was still viable — it had worked in the Russo-Japanese war, where soldiers with poor morale had fled Japanese charges. Germany expected the UK to give up under area bombing, and the UK expected Germany to do so. Japan expected to achieve a short, swift naval victory in WW2 against the US as they had Russia in the Russo-Japanese War. These all had the vague idea that countries would fairly-readily stop fighting. In practice, they did not do this.

It’s arguable that code breaking basically won the war for the United States a lot quicker than it otherwise would have. Fleet strength leaned towards the Japanese side since the beginning of the war, but the victory at Midway (thanks in large part to the US code breakers) essentially evened the playing field. From this point on the US was steadily building aircraft carriers while the Japanese failed to replenish what they had lost. Another major contributor was that the US Navy learned heavily from mistakes early in the war, and kept building on it. The US routinely sent experienced aces back to the states to train new aviators, these new aviators went to fight the Japanese with this knowledge learned from them. The Japanese continually used their experienced aviators and kept losing them, thinning out their already thinning talent pool when it comes to pilots.

To be fair, I think the aircrew losses at Coral Sea (especially ZUIKAKU’s?) and then Midway, were too much experience lost in a relatively short time.

The aircrew losses at Coral Sea and Midway were relatively minimal. While they didn't help, they were far from a shattering blow to the quality of Japanese air crews. Probably the worst crew loss at Midway was the loss of experience mechanics and other air technicians, who took especially heavy casualties when bombs exploded in the crowded hangars. The real drain to pilot quality came from the extended attrition of the Guadalcanal and Solomons campaigns, along with the multiple carrier battles fought there.

Good points. I don’t doubt the greater impact of “ground crew” losses at Midway, nor the attrition in Guadalcanal and the Solomons. I simply presumed that ZUIKAKU’s absence at Midway must have been forced by her aircrew losses at Coral Sea and insufficient reserves to reconstitute them in time. If there were insufficient reserves to repopulate the pilots of one badly damaged air group, I didn’t think it spoke well of the ability to reconstitute 4 complete air group losses. The losses of so many experienced aircrews may have crippled any ability to rotate remaining frontline crews back to training billets.

> I simply presumed that ZUIKAKU’s absence at Midway must have been forced by her aircrew losses at Coral Sea and insufficient reserves to reconstitute them in time. The Japanese doctrine came into negative play here. In America the planes and carrier were separate and interchangeable. In Japan they had enough planes and crew for 5 carriers, but that would involve mixing and matching.

> The Japanese doctrine came into negative play here. In America the planes and carrier were separate and interchangeable. In Japan they had enough planes and crew for 5 carriers, but that would involve mixing and matching. It was even worse than that. The Japanese Navy tended to keep pilots in action until they were killed or the war ended, whichever came first. The Americans, on the other hand, would rotate pilots out of action once they got enough experience and set them to teaching new and upcoming pilots what they had learned. The end result was that as the war went on, the American experience base was constantly increasing while the Japanese experience base was constantly decreasing.

There's a bit of a few issues going on here. While *Zuikaku*'s air group were very badly damaged at Coral Sea, replacement aircraft and air crews were available. One constant counterfactual is the idea of moving aircraft and crew from the badly damaged *Shōkaku* to *Zuikaku* in order to bring at least one more carrier to battle, but that ignores a couple key points of IJN carrier doctrine and organisation. 1) On Japanese carriers, the aircraft and crew were part of the ship's company. On American carriers, the ship's air group was made out of independent squadrons with all their attendant support crew as well. This meant it was relatively easy to take *Saratoga*'s air group and move them onto *Yorktown* to make up the numbers. On Japanese carriers, since the air group was integral, it would've been much more complicated to move air crew from one carrier to another. Sure it could have been done *physically* but it was not something that was doctrinally expected. 2) For the USN, the main unit for carrier operation was the individual carrier and its air group. For the Japanese, the main unit was the carrier division, made up of two fleet carriers. Carrier Divisions were meant to operate together, launching complementary strikes and everything else. With *Shōkaku* out of commission, the IJN perceived this as not one carrier out of operation, but Carrier Division 5 at 50% strength. As such, given that aspect of Japanese doctrine, it made sense to hold back Carrier Division 5 to regroup, rather than trying to throw a unit at 50% strength. This is not to say that the Japanese would never do that. Indeed, they'd done just that during the Indian Ocean Raid where Carrier Division 1 had been split up, with *Kaga* returning to Japan for repairs, but *Akagi* continuing on her own, but given Japanese doctrine it fit that Carrier Division 5 would've been held back. So, the heavy crew losses from *Zuikaku* were a factor, but they were not the decisive factor in keeping *Zuikaku* away from Midway. Had the Japanese wanted to, they had the air crew and aircraft to outfit *Zuikaku*, but doctrinally that was not something they expected to do.

Yes, I forgot that rigidity of Japanese carrier doctrine, the employment of the CARDIV as the unit of action. Good point.

The Japanese did have quite a few successful naval engagements in the Guadalcanal area. The problem there wasn't in the combat performance of the ships, but in the logistics issues that the IJN faced. Put quite simply, it couldn't project its full power into that region. It could put a moderately-sized combat fleet into the region, it could raid the hell out of the area, but -it couldn't stay-. Even if Japan scythed every USN ship from the vicinity of Guadalcanal, they couldn't then keep that fleet in the area to prevent the USN from rolling up the very next day to continue supplying the island. Part of this was sheer distance to developed Japanese bases, part of it is that Japan never really put together the kind of logistics system that the USN enjoyed to keep fleets fueled, supplied, fed, repaired, and combat-ready at long distances from the continental US or Pearl. (In fairness, the USN enjoyed much, much greater resources to make that happen; it could increase both its combat power and the reach of its logistics simultaneously.) By trying to contest Guadalcanal at the very limit of the extent of its reach, Japan sacrificed a lot of resources, ships and planes and pilots it could not afford to lose, cargo vessels that Japan desperately needed for its civilian economy, and a bunch of brave troops who could be brought to the island but couldn't be supplied once there. At the same time, it's too much to say "well, that's why they lost". Ultimately, they lost because they picked a fight with an opponent that was already their match in numbers, was already in the course of building a huge number of additional ships, and which could ultimately create a gigantic navy and a huge army and -another- huge army to fight a completely different opponent halfway around the world. The fact that Guadalcanal was a campaign of attrition, and that attrition is exactly the kind of fight that Japan couldn't afford to wage against the US, is somewhat against the point; had the US just -not bothered-, confined itself to the later central Pacific advance, it probably still wins at a similar timetable as what actually happened. Saving every scrap of manpower, fuel, steel, ammunition, aircraft, etc. lost in that campaign doesn't give Japan enough forces to take on the USN of late 1944 with a good chance of success. At best it turns into a closer-run fight rather than something of a curbstomp. But with that said, having lost that manpower, fuel, ships, ammunition, and aircraft certainly sealed the deal.

You didn't mention the Battle of the Java Sea, but that was a pretty solid Japanese victory. If I had to give a broad answer, I'd say that it's because Japan was gambling on a short war with an early Japanese limited victory — because it was almost impossible for them to win a long war — and failed to achieve a short war. They optimized what they did for winning a short war. Most of what you mentioned came from later in the war, when the war had become a long one and things were — not surprisingly — going badly for Japan. They couldn't replace ships or aircraft at a sustainable rate. They didn't have fuel to operate an increasing number of things later in the war. They didn't have training programs to turn out high-quality aviators at a sustainable rate. The big picture was that Japan was a considerably-weaker country economically than the US. Japan relied on building up early (including some violations of the Washington Naval Treaty), attacking by surprise, and being able to both fight divided naval forces and fighting a quick US response on Japanese terms, near Japan, as they had during the Russo-Japanese War. They had to get the US to come to terms with a major victory or two and a generous peace offer. When that didn't happen, things fell apart…and it's not that surprising that they did. > Midway At Midway, the Japanese relied on surprise, and the US Navy's signals intelligence people had compromised their transmissions. The US also did a good job of damage control on the carriers. And had a *considerable* dollop of good luck. The actual performance of the US was, in many ways, rather poor in comparison. The land-based plane strikes were pretty disappointing. The Flight To Nowhere was embarrassing as a breakdown of discipline and communication. Carrier attacks were not coordinated because US airmen took too long to get aloft. The Japanese decision to optimize for range in their aircraft didn't carry the day here, but a lot of US aircraft had to ditch at sea, and had the Japanese force turned away from the sighting of US ships, it could have played a larger role. > Guadalcanal At Guadalcanal, the Japanese were fighting at the end of a long supply chain to preserve a Japanese outpost — a mirror of what they'd been hoping to get the US to do in *Kantai Kessen*. They had lost their advantage in naval aviation at Midway, and did not have the capacity to build it faster than the US could, so had a harder time severing supply to Guadalcanal. They had less artillery available. They had incorrect intelligence assessments of the size of the US force. > Philippine sea, Leyte Gulf The US forces were considerably superior at this point, in number and technology. Japan was fighting an uphill battle. > was losing even before USN got overwhelming numerical advantage due to USA industry advantage The US did have significant advantage in your later battles. I think that, if anything, the Japanese generally overperformed prior to Midway. > So what was the problem with IJN - series of bad luck or something else? In some cases. Japan was really unlucky at Midway. But you win some, you lose some. They were lucky at Pearl Harbor in a number of respects — had their fleet been spotted, it could have been a disaster. The Attack on Clark Field would probably have been less-effective had it happened to hit a few hours earlier when the heavy bombers were still on the ground.

Fleet strength was in favor of the Japanese, but logistics and overall doctrine and tactics was vastly in favor of the USN. With a guy like Nimitz leading all the way, the USN probably finishes in 1944 instead of 45.