Japan's losses at Pearl Harbor were catastrophic

Today is the 75th anniversary of the attack by naval forces of Japan against American installations at Pearl Harbor, Hawaii. Here are two little-known facts about Japan's operations against Pearl Harbor, Hawaii, and one better-known fact.

The destroyer USS Shaw explodes during the Imperial Japanese Navy's surprise attack on the morning of Dec. 7, 1941. The attack was a tactical success but its plan was a strategic failure from the beginning. In just a few hours that day, Japan's navy lost more than one-fourth of its annual pilot accessions.

Little-known fact 1, which I learned recently reading Jim Dunnigan's article about the perils of declining flight hours of present-day US Air Force pilots: "the 29 pilots [Japan's navy] lost at Pearl Harbor represented more than a quarter of the annual crop" of new pilots (emphasis added). The reason? Japan's navy pilot training and certification program was at that time the most rigorous and difficult in the world. A trainee pilot needed 700 certified flight hours just to attain minimum status as a full-fledged fleet pilot. In contrast, at war's start, three-fourths of US Navy fleet pilots had fewer total flight hours than the least-experienced Japanese navy pilot. [See endnote for further discussion about these figures and assessment.] But the Japanese navy had shot itself in the foot enforcing such high standards. Its commanders deliberately, though not unreasonably, pursued very high quality over very high numbers, knowing that their country could not successfully wage a long war. Their intention was to put into the air such superior pilots that no enemy pilots could prevail even with larger numbers.

Early in the war many American pilots called their Japanese counterparts "Hell on wheels," and for good reason. 

But Japan's admirals did not account for the fact that their highly-skilled pilots would be just as vulnerable to American anti-aircraft fire as average pilots. They did not assess that American pilots, though not highly trained, would prove to be well trained. Consequently, in just the first year of the war the Imperial Japanese Navy lost so many pilots that it had to reform pilot accessions. By then it was too late. Japanese training flight hours steadily and finally sharply declined while US pilots' training hours steadily increased. In fact, from "late 1944 into 1945, nearly half the pilots in Japanese squadrons had flown fewer than 200 hours. The disparity of two years before had been completely reversed." The United States showed both in the Pacific and in Europe that it was possible to obtain both quantity and quality, but then, only the United States had both the human and material resources to do it. But it took time and cost many lives and aircraft. During the opening year or two of the war,

Some fighter pilots entered combat in 1942 with less than one hour in their assigned aircraft. 

The 357th Fighter Group (often known as The Yoxford Boys) went to England in late 1943 having trained on P-39s. The group never saw a Mustang until shortly before its first combat mission. A high-time P-51 pilot had 30 hours in type. Many had fewer than five hours. Some had one hour.

Despite such wartime exigencies, those American pilots did have an ever-increasing advantage that their enemies lacked: they were flying more and more hours in pilot training.

[T]he U.S. Navy was actually increasing its flight time, while keeping pilot training programs to about 18 months. In 1943, the U.S. Navy increased flight hours for trainees to 500, while Japan cut its hours to 500. In 1944, the U.S. hours went up to 525, while Japan cut it to 275 hours. In 1945, a shortage of fuel had Japanese trainee pilots flying only 90 hours before entering combat.

Only the United States had both the production capacity and the manpower to prevail under such conditions. "At its height in mid-1944, the Army Air Forces had 2.6 million people and 80,000 aircraft" and could absorb the loss of "14,903 pilots, aircrew and assorted personnel plus 13,873 airplanes — inside the continental United States" (emphasis added), or about 40 stateside accidents every day of the war. Another "43,581 aircraft were lost overseas" of which only a little more than half were combat losses.

But the same situation for both Japan and Germany was dire. "Through much of 1944, the Luftwaffe sustained uncontrolled hemorrhaging, reaching 25 percent of aircrews and 40 planes a month," an unsustainable loss rate for German industry and manpower to cope with, especially considering that Germany's aircraft plants were being bombed regularly. For both Germany and Japan, the main limiting factor in pilot training was fuel. Japan produced almost no domestic oil and America's submarine fleet priority-targeted Japan's tanker ships. It was very effective. Japan had rolled its dice on a short war. Its pilots took such severe losses in just a year that Japan's navy was never able to recover.

Little Known Fact 2: Japan's second air raid against Pearl Harbor was of much worse consequence strategically for Japan than the attack of 7 December 1941.

Another raid was planned just three months after the initial attack. The idea was to hit the carriers while in port and to disrupt the repairs of battleships that had been damaged in the December attack. This time, a large naval fleet would not be practicable as the element of surprise was lost. Instead, two giant flying boats - the most advanced in the world at the time - would make a daring attempt to attack Pearl Harbor at night.

The Japanese "Emily" long-range flying boat. Equipped with eight bombs each, two set out for a night attack against Pearl Harbor on March 4, 1942.

[T]he planes took off for a night bombing raid on Pearl Harbor. They flew to the French Frigate Shoals in the north western part of the Hawaiian Island chain, where they were refueled by the submarines I-17 and I-19, which had been modified with special tanks for carrying aviation fuel. Seven hours later, the planes approached Oahu.

Because there was no moonlight and it was raining, American air defenders could not locate the Japanese planes, though radar detected them.

Due to the cloud cover, the Japanese planes also could not find their targets and had to drop their bombs blind, some of which hit inland from the harbor and two at the harbor entrance. No ships were damaged. The flying boats returned to their base.

The raid was a worse failure than merely not hitting the targets. It didn't take long for US naval intelligence to figure out that the flying boats had to have refueled  at French Frigate Shoals, between Hawaii and Midway Island.

For the rest of the war, the US Navy made sure that Japan would never again use FFS for any reason. Only three months after this abortive air raid the US Navy sank four Japanese aircraft carriers and killed 2,500 officers and enlisted ranks at the Battle of Midway, losses that permanently placed Japan on the strategic defensive. Japanese intelligence had been convinced that the US could not defend against its fleet, mainly because USS Yorktown had been so badly damaged in May at the Battle of Coral Sea, where USS Lexington had been sunk. Yorktown did fight at Midway with full capability, though it was badly damaged by Japanese air attacks and was then sunk by a Japanese submarine.

Japan would have been better advised to use FFS as a station from which to refuel reconnaissance flights, not bombing missions, against Pearl Harbor. If so, it may have learned that Yorktown was en route to Midway along with two other carriers, and the outcome of the Midway battle might have been quite different.

Better-known fact: Japan's concentration on Dec. 7 against US Navy warships was incalculably bad planning and strategic analysis. Their target was the American fleet, mainly its aircraft carriers. But all the US carriers were at sea. The attacks against the US battleships were very successful, but they sank in shallow water, being moored next to Ford Island, and except for Arizona, and suffered relatively few deaths of crew. American airfields were also bombed and strafed, resulting in wholesale losses of American aircraft.

What Japan practically ignored was Pearl Harbor's logistic and shore-based, support facilities. In particular, attacks against fuel storage and transportation systems would have been devastating. I remember reading that the Navy assessed that such an attack would have mostly immobilized the Pacific Fleet for almost two years. (Since the battle, many historians have persistently reported that Japan's air commander, Mitsuo Fuchida, insisted to Admiral Chūichi Nagumo, commanding the strike fleet, that a third strike be launched against Pearl's oil infrastructure and dry-docks, but that Nagumo refused, ordering the fleet to withdraw since the at-sea US aircraft carriers' location was unknown. The problem with that account is that the raid's chief planner, Minoru Genda, maintained after the war that no third strike was ever planned or contemplated and that Fuchida never even broached the suggestion.)

IJN planners and admirals may have ignored the harbor's logistics vulnerabilities because they were mostly ignoring their own.  David C. Evans and Mark R. Peattie argue in Kaigun: Strategy, Tactics, and Technology in the Imperial Japanese Navy 1887-1941 that Japan's main reason for taking over Borneo and other areas of the southwest Pacific was to secure oil supplies for the homeland - yet the IJN gave this requirement practically no consideration either of planning or equipping. "Before the war, Japan needed ten million tons of merchant shipping to meet its needs." Yet after hostilities began and merchant shipping was snapped up by other requirements,

Only 30,000 tons of tankers remained to ship the essential oil supply from Borneo to the refineries in Japan. This lack of attention to the very aim of the war – oil – helps to explain why the oil supplies at Pearl Harbor were never targeted. The refusal to deal with logistics and mobilization issues affected the conduct of the war from the very beginning. 

Japan's high commanders, with very few exceptions, simply did not deal with such matters for themselves, and this nearly automatically led them to ignore such issues regarding their enemies. The most serious catastrophe for Japan at Pearl Harbor was its short-term focus on ships as targets. Before the war,  Admiral Isoruku Yamamoto, commander of the Imperial Japanese combined fleet, argued strongly against going to war with the United States. He told the high command, "I shall run wild considerably for the first six months or a year but I have utterly no confidence for the second and third years." He was optimistic. In fact, the Japanese navy won battles for only four more months.

And that can be largely blamed (or credited, take your pick) on the tactical, rather than strategic focus of the Dec. 7 attack. Japan's lack of a national grand strategy or even the rudiments of deep strategic thinking are illustrated by asking one simple question: Why attack Pearl Harbor at all? Sherman Miles, who was serving at the highest level of the War Department on the day, wrote only three years after the war,

Had Japan not attacked us when the Washington conference failed, there were but two courses of action that could have resulted in our interference with her policy of conquest. The President might have persuaded Congress to declare war, or he might have interposed U.S. forces in the path of the Japanese advance. The Administration's difficulties would have been great and its success problematical in either case. And how the isolationist elements in the country—the “Hearst-McCormick-Patterson Axis,” “America First,” and others—would have howled! American lives to be sacrificed in defense of British and Dutch colonies, and Siam! All this the Japanese must have known. They certainly missed a bet, once they realized that their negotiations in Washington would fail, in not going about their southern business and leaving us out on a limb.

Japan's rulers seem to have simply assumed that the US would militarily block Japan's actions against the nations or European-ruled territories of the southwest Pacific area. But that betrays a severe misunderstanding, nay outright ignorance, of America's domestic politics and naval capabilities.

Japan's invasion of the US-ruled Philippines, started the same day as the Pearl Harbor attack, would certainly have evoked American military countermeasures. But what and for how long and with what result? The Navy Department did not conceive of the US Pacific Fleet as a force-projection fleet, but as a deterrent against Japanese movements against Hawaii and the American mainland. Hawaii was at that time considered to be the far-western bulwark against Japanese expansionism. In fact, says Miles, "I remember Admiral Kelly Turner expressing in a British-American staff conference, six months before Pearl Harbor, his confidence in our ability to hold the Japanese Navy in home waters simply by having our fleet cruise in the mid-Pacific." Moreover, US naval opposition to Japan's moves would have been militarily impossible, not just politically:

It has been argued that the Japanese were bound to attack our fleet on resuming their policy of conquest because it constituted an intolerable strategic threat on their flank. The fleet was certainly an important element in Pacific strategy, and its damage or elimination was highly desirable from the Japanese point of view. But as a matter of fact, it was not an immediate menace to Japan, nor could it have seriously deterred her in the early months of whatever campaign she might decide to initiate behind the shield of her mandate islands. For our fleet, in any operations in the Far East, would have been distinctly inferior to the Japanese in air and sea power and particularly in logistic support. We had no bases beyond Hawaii capable of handling the fleet. We lacked the “train,” the great force of supply and repair ships, that would be necessary for such distance operations. This also the Japanese must have known. Not even the most extreme misconception as to the relative efficiency of the opposing forces would have led our fleet so far from its base for a considerable period of time. Or if it had, Admiral Yamamoto could have solved his problem still more tragically for us.

Solving the problem "more tragically" means simply that had the Pacific Fleet attempted to engage Japan's navy on the open sea, it would have lost more severely than at Pearl Harbor, with ships, including our few aircraft carriers, sunk to the deep ocean bottom and enormously higher losses of crews. Such a likely outcome was explicitly stated by Admiral Chester Nimitz in 1964:

... Admiral Chester Nimitz, who took over as commander of the Pacific Fleet three weeks after the attack, concluded that "it was God's mercy that our fleet was in Pearl Harbor on December 7". If [Admiral Husband] Kimmel [commanding the Pacific Fleet on Dec. 7] had "had advance notice that the Japanese were coming, he most probably would have tried to intercept them. With the difference in speed between Kimmel's battleships and the faster Japanese carriers, the former could not have come within rifle range of the enemy's flattops. As a result, we would have lost many ships in deep water and also thousands more in lives." ... This was also the assessment of Joseph Rochefort, head of Station HYPO, who remarked the attack was cheap at the price.

Nimitz was clear that the fate of Pearl Harbor's fleet engaging the IJN on the open sea would have been its destruction. Station HYPO, btw, was the "United States Navy signals monitoring and cryptographic intelligence unit in Hawaii during World War II." One must wonder why Japan did not leave the US fleet alone at Pearl and make its moves against the Philippines and elsewhere, wait for the US fleet to sally forth, and then destroy it on the open ocean. That had after all been the IJN's basic planning template for 20 years. Miles explains that American Army and Navy planners badly and consistently underestimated Japan's military capabilities and skills. Might the Japanese have overestimated those of the Americans? This despite the fact that the US fleet of late 1941 was a mere shadow of that which would turn the entire Pacific Ocean into an American pond by the end of 1944.

The IJN's overarching strategy was called kantai kessen, "decisive battle." It came from Japan's resounding naval defeat of Russia in 1905 in the Russo-Japanese war's Battle of Tsushima. It was postulated on drawing an enemy into a single engagement where the enemy fleet would be crushed by attacking Japanese battleships and cruisers. Even though by the mid-1930s forward-looking Japanese officers knew the aircraft carrier and modern submarines had rendered the kantai kessen doctrine obsolete, they were neither numerous nor senior enough to change the high command's steadfastness to it.

Their basic plan since the 1920s was this: The decisive battle would take place north of the Marianas Islands within easy sailing distance by the Japanese Combined Fleet with total offensive combat operations phased over two weeks. Yet this long-held, well-developed operational concept was abandoned in favor of a three-hour air raid. Why?

Japan's Pacific empire before the Pearl Harbor attack

The answer is that they thought the attack against the US fleet at Pearl Harbor would be decisive, at least decisive enough to enable Japan to conquer its new targets and cement an unbreakable hold on them. But of course, this was a fatally-flawed calculation. Military historian Gary A. Gustafson summarized Japan's strategic deficiencies thus:

The Japanese way of war envisioned by Akiyama, validated at Tsushima, codified by Sato, and instilled in the IJN by the Naval Staff College, was an amalgamation of Western and Eastern thought combined with the samurai traditions of Japan. By ignoring the complete lessons of the outsiders, the IJN created a doctrine that was limited to a single mode of war. ... IJN doctrine created an offensive mindset; but, not to invade, conquer and annihilate. Rather, it was to lure in and ambush. Offensive action for the IJN meant raids that helped to dictate the course of battle and manipulate their enemy into a complex, inflexible trap at the time and place of their choosing. It was a tactical doctrine of battle, not a strategic doctrine of war. 

Miles says that neither America's estimate (overly low as it was) of Japan's abilities nor the disadvantages accruing to America if America bore the burden of initiating war with Japan (in response to its new territorial seizures) were lost on the American War and Navy Departments. They agreed that the US would go to war with Japan sooner or later.

The high command of our Army and Navy thought they had prepared for either eventual or immediate war, so far as it was humanly possible to do so. But still it was difficult to predict, and indeed we did not predict that the Japanese would commit so great a blunder as Pearl Harbor, gratuitously unifying the war spirit and potential of America. We overestimated their intelligence. That blunder in the realm of high policy eventually cost Japan her empire. But that was not all. On the lower plane of tactics the Japanese decision to attack Pearl Harbor by surprise involved enormous risks. As [US Army Chief of Staff] General Marshall later testified: “A surprise is either a triumph or a catastrophe. If it proved to be a catastrophe, the entire Japanese campaign was ruined.”

General Marshall understated the result. Not just a campaign but Japan itself, as a whole, was ruined by the catastrophe of its attack on Pearl Harbor. Update: Business Insider has a good photo essay of the attack. So does the Buffalo (NY) News. Update, Dec. 9: Retired US Navy Commander Dr. Alan D. Zimm of the Strike Systems Analysis Group of The Johns Hopkins University's Applied Physics Laboratory emails an inquiry of the claim, above, that Japanese navy pilots were as highly trained as I indicate, and that his own information is that,

... before Pearl Harbor, basic flight training for Japanese aviators was about 400 hours.  This did not include any advanced flight training or tactical training.  Advanced training and tactical training, and thing like gunnery training, was accomplished at the operational unit level.  As a preliminary to Pearl Harbor, most of the aviators below the Daitai leadership level (some of which were China veterans) got an additional 100 hours of training, that brought their average flight hours up to about 500-600 hours.

So I am sending him my source citation and we'll see where this shakes out. Dr. Zimm also has online at the US Naval Institute a very interesting article on how the Japanese air commander at Pearl, Commander Mitsuo Fuchida, botched the air raid significantly by signaling the strike aircraft that surprise attack had not been achieved (which it certainly had been), how this error reduced Japanese effectiveness, and how Fuchida tried to CYA about it after the war. See, "Commander Fuchida's Decision." Further, Dec. 14: Dr. Zimm holds in very high suspicion the figure of 700 training flight hours that Jim Dunnigan reported and that I used near the beginning of this post. Dr. Zimm says via email that the characterization of Japanese pilot training as "the most rigorous and difficult in the world" is also not justified by other Japanese accounts:

Two examples:  the Shokaku and Zuikaku aviators could not get night flying certified, and so the launch time of the attack had to be put back to dawn, from the original concept that the attack would launch in the dark and arrive over Pearl Harbor at dawn. 

The second is that the Zero pilots got very little gunnery training before Pearl, because they had to concentrate on launch and recovery, deck handling, and basic airmanship such as formation flying.

This caused me to revisit the autobiographical account of the highest-scoring Japanese ace of the war, Saburo Sakai, who scored 64 kills, four of them after recovering from grievous wounds, including being blinded in one eye. His account is in the book, Samurai, as told to US aviation historian Martin Caiden. Sakai does not discuss in very great detail his months of flight training. So a point summary from chapter 3 is:

• Constant aggressiveness was drilled into them and enforced ruthlessly, but this training was nt oriented toward actually flying a plane. It was a quality desired, not a skill. 
• The first month was ground training, after which began primary flight lessons.
• The total course length was 10 months, during which 45 of the original 70 pilot trainees washed out. 
• There was no physical punishment (such as beatings, which were commonplace in Japanese training) because the trainee's fear of being dropped made it unnecessary. One trainee was expelled literally the evening before graduation for a rules infraction.
• The physical training courses were "among the severest in Japan" and included difficult swimming requirements (which makes sense for naval pilots). 
• This training including diving lessons to improve sense of balance for later aerobatics. Diving was from high platforms into water and later onto the ground from height, always required to land on their feet. "Naturally, there were errors - with disastrous results."
• Acrobatics was taught for the same reasons. 

In chapter 4: "Despite our excellent and arduous instruction, several pilots from my group [graduating class] were later killed by enemy pilots before gaining even a single victory." In fact, Sakai was the only pilot of his class to survive the war. After graduation he and the others were assigned to units for "service training." The pilots already there, he said, had skills that were "astonishing." This phase lasted three months, consisting of carrier qualifications and land-based flying and combat training. He found carrier landings especially challenging to master, though for the whole war he never flew even one combat mission from a carrier. So was the training of Japanese pilots rigorous and difficult? Unquestionably. The IJN received 1,500 applicants for a place in Sakai's training class, accepted 70 and graduated 25. The course's rigor and difficulty can't be denied, but what can be questioned, as I believe Dr. Zimm is doing, is whether its rigor and difficulty were actually all that beneficial for combat performance. This is highly open to question. That at least some was can't be gainsaid; Sakai points out that developing very fast reflexes and improving eyesight cognition were literally lifesavers in battle. But it's pretty unclear what somersault dives from 10 meters onto hard ground deliver besides some unnecessary casualties. Here is what Sakai says about this post's topic, however:

And I will let that be the last word.