Attack on Pearl Harbor (7 page)

Yamamoto substituted his vision of a short war coming to a negotiated end—based on the psychological shock of Pearl Harbor and the loss of the Philippines and southern resource areas—for the Naval General Staff’s vision of a short war culminating in
Zengen Sakusen
. This realization gives better context to Yamamoto’s statement, “If we fail [at Pearl Harbor], we’d better give up the war.” He clearly had no confidence in
Zengen Sakusen
. Failure had to be defined not in terms of the results of an attack on Pearl Harbor but in terms of achieving what was needed to bring the Americans to the negotiating tables. If the attack on Pearl Harbor succeeded but did not result in negotiations, the losses caused by a successful attack would force the Americans into a long-war strategy, the very war in which Japan had no hope of victory.

It has been suggested that the strategies were actually complementary: a Pearl Harbor raid would reduce the effectiveness of the Pacific Fleet at the outset of the war, something like an early phase of Interceptive Operations, followed by the Decisive Battle that would convince the Americans that victory was not worth the necessary sacrifices. But Yamamoto did not believe that the Americans would behave in a manner to allow a Jutland-style battle at the outset, and there was no reason to believe that losses at Pearl Harbor would stir Americans into committing the fleet with inferior force ratios. Yamamoto had not thought ahead to consider a situation where the losses at Pearl Harbor did not bring the Americans to the negotiating table. The cobbled-together nature of the staff work and negotiations with the Imperial Army preceding the Midway Campaign was the result of Yamamoto’s lack of foresight, as he tried to improvise his way out of the strategic situation he had imposed through the success of the Pearl Harbor attack. At least in Yamamoto’s mind, there was no complementary connection between Pearl Harbor and
Zengen Sakusen
.

The psychological aspect of Yamamoto’s objective (as opposed to material destruction) should not be dismissed. It played a significant role in how the Japanese would go about achieving their material objectives. In particular, the psychological aspect called for the attackers to prioritize the American battleships. Rear Admiral Onishi, Chief of Staff of the Eleventh Air Fleet, said Yamamoto believed that “Most Americans—like most Japanese—still believed battleships to be the mightiest weapons of war. The sinking of one or, better yet, a number of these giant vessels would be considered a most appalling thing, akin to a disaster of nature. Such destruction, Yamamoto reasoned, would paralyze the vaunted Yankee spirit.”
⁶⁵

Yamamoto was after headlines, front page photographs of destroyed battleships. The target was the American people, a people with a prominent and vocal pacifist contingent who were placing pressure on elected representatives not to involve American troops in foreign wars. Most Americans couldn’t find Luzon on a map. The Philippines were to be given their independence in five years. Why spill American blood to prevent something that was already scheduled to happen?

Yamamoto believed that if Americans could be induced to despair they would place pressure on their government to end the war, leaving Japan in possession of the southern resource areas. He asserted that “American public opinion has always been very changeable, so the only hope is to make them feel as soon as possible that it’s no use tackling a swarm of lethal stingers…. And the one other thing we can do is to take bold risks, resigned from the start to losing up to half our own forces.”
⁶⁶

Yamamoto did not understand the Roosevelt Administration. They saw things not as “the Japan problem” and “the German problem,” but the problem of defeating the Axis
en toto
. There would be no contemplation of a separate peace with Japan. Pearl Harbor eliminated Japan’s greatest potential negotiating tool, its offer to switch sides and join the Allies against Germany as the price of a separate peace. The Japanese assumption that a separate peace was possible was fatally flawed.

The losses at Pearl Harbor and the Philippines did not induce despair. The Americans were not interested in a negotiated, separate peace. With their pre-war assumptions exploded, Yamamoto’s fallback was
Zengen Sakusen
, with a twist. He must force a final decisive battle onto the enemy by an attack on Midway, which Yamamoto thought would flush out the American battleline. Yamamoto extemporized his way into a course of action that became the greatest role reversal in history.

After six months of war he gathered together a massive fleet to steam east. He placed himself on what he had proclaimed to be that world-class “folly,” the battleship
Yamato
, and led an invasion fleet against the island of Midway. He was opposed by Midway’s concentrated air power and the American carriers, in what the Japanese would call an Interceptive Operation. Yamamoto took the course of action Japan had wanted the Americans to take, and the Americans’ Interceptive Operations did to the Japanese what the Japanese had hoped to do to the Americans.

Even if victorious in the carrier preliminaries, Yamamoto would not have gotten his
Zengen Sakusen
, as the Americans did not commit the battleships of Joint Task Force One to defend Midway.

The Battle of Midway has to stand as the greatest irony in military history.

Initial Estimates

Yamamoto initially consulted with his close friend Rear Admiral Onishi Takijiro, Chief of Staff of the Eleventh Air Fleet, asking him to begin a study of the feasibility of an attack on Pearl Harbor. They eventually discussed the concept. Yamamoto concluded from the meeting that the attack would be “so difficult and so dangerous that we must be prepared to risk complete annihilation.”
¹

Onishi brought in Commander Genda Minoru, the Air Staff Officer of the First Carrier Division. Genda and Onishi were friends, and had discussed a carrier attack on Pearl Harbor several years previously. Genda was a naval aviator with a reputation for iconoclastic brilliance, but also known as “Madman Genda” at the Naval Staff College because of his radical advocacy of aircraft and his expressed belief that all battleships ought to be scrapped.
²
He was an advanced thinker regarding the employment of aircraft at sea. His theories became known in the Japanese fleet as “Gendaism.”

Genda thought an attack on Pearl Harbor would be “difficult but not impossible.” He worked on a draft concept of operations and preliminary assessment, which he presented to Onishi in February. He believed surprise was necessary. The main objective of the attack should be the enemy carriers, with a high priority given to land-based aircraft. The American’s main base in the Pacific was, in modern terminology, “target rich,” with more worthwhile targets than could be serviced by the aircraft from Japan’s four fleet carriers.
³
He recommended a balanced daylight attack employing torpedoes, bombs and fighters. There would be sufficient bombs and torpedoes only for the most important targets. Strike assets would have to be carefully allocated. Genda asserted the principle that light damage inflicted to many targets would be trivial and readily repaired, while heavy damage inflicted on key targets could be debilitating. This called for careful allocation of effort.

The key targets were generically separated into two categories: First, capital ships, the destruction of which was expected to lead to achieving the primary objectives of the attack; second, targets necessary to keep the Japanese strike aircraft and Japanese warships safe.

There was a third category, that of base infrastructure and logistics facilities. This would include things like the shipyards, drydocks, the submarine base, supply depots, administrative buildings, barracks, and fuel storage. These were not targeted. The striking aircraft simply could not carry enough bombs to do everything. The Japanese should direct their efforts against the fleet and American air power, not facilities.
⁴

Onishi took Genda’s draft and, after some modifications, presented to Yamamoto what we would now call a “white paper” of some ten pages. Planning began in earnest, expanding to bring in more and more subject matter experts and staff officers. Genda was eventually assigned to handle all portions of the planning relating to aviation, including studies and training.

The exact requirements of the objective are important. The American fleet was to be immobilized for six months. Heavy damage inflicted on battleships, particularly torpedo or AP bomb hits, would keep them out of the war for at least six months even if there were fully-operational repair facilities available.

One torpedo hit can put a ship out of commission for months, even if it is hit while closed up for battle. It is not just the hole in the side of the ship and the smashed equipment, but there is also wiring and insulation and pumps and motors and stuffing tubes and other sundry gear that is damaged by salt water, an insidious, corrosive liquid. Shock can damage systems far away from the torpedo hit: torpedo explosions have put gun directors high on a ship’s superstructure out of commission. Pumps can be shocked out of alignment or bounced off their foundations. A British study conducted in 1943 of torpedo hits on cruisers found that, in the 19 cases examined, the average repair time was 9.5 months.
⁵

AP bombs also could immobilize a battleship for six months if they penetrated into the engineering spaces. In 1937, during damage effects experiments using the obsolete battleship
Hannover
, the Germans detonated 28cm (11-inch) and 38cm (15-inch) AP shells in her boiler and engine rooms.

The 28cm shell caused immediate debilitating damage. Burst steam piping would have forced the space to be evacuated. However, the damage was not so extensive as to preclude repair during a yard overhaul of less than six months.

The 38cm shell completely destroyed the equipment in the spaces (boilers or engines), requiring complete new installations. The repair work would have required at least six months, more if spare assemblies were not immediately available.
⁶

These tests would tend to underestimate the damage effects of a shell. The shells were stationary when detonated, so that all the kinetic energy put into the shell fragments came only from the energy released by the explosive charge. The German 28cm APC shell had a bursting charge of 14.55 pounds generating about 27 megajoules, while the 38cm APC had a bursting charge of 41.4 pounds for 78 megajoules. The kinetic energy of the mass of the shell itself would depend on the residual velocity after it penetrates the armor, which would depend upon terminal velocity, armor thickness and orientation, and a host of other factors. If the shell retained 100 meters/second residual velocity (out of a striking velocity on the order of 700 meters/second), another 2 megajoules or 4.3 megajoules, respectively, or 7%, would be added to the energy total.

It is not known if the Germans passed on the results of their tests to their Japanese allies before the Pearl Harbor attack. However, the Japanese had performed similar tests against
Tosa
in June of 1924 and likely reached similar conclusions.

As will be shown in further pages, even several hundred bombs would not have placed the repair facilities out of commission. But if torpedoes and bomb hits on battleships could do the job, then striking infrastructure targets would have been unnecessary—they were irrelevant in the context of the six month objective. In fact, Japanese planners never even considered them as targets.

The first priority targets were the capital ships of the fleet, both the battleships that would provide the headlines and the aircraft carriers that could threaten the Japanese fleet with counterattack. Part of the strike would be directed against American air bases in what is known in modern terms as offensive counter-air (OCA), to keep fighters from interfering with the Japanese bombers and to prevent bombers from counterattacking.

The Japanese feared land-based air. Yamamoto originally considered a one-way attack employing only torpedo bombers. If this was not feasible, he suggested launching a full strike from 500 to 600 miles off Oahu in a one-way attack (
katamichi kogeki
). The aviators would ditch in the vicinity of Pearl Harbor and be recovered by submarines. Yamamoto estimated that when the American people saw this form of attack they would think the Japanese “such a unique and fearless race that it would be useless to fight them.”

Genda rejected Yamamoto’s concepts. “A one-way attack would have a bad psychological effect on the airmen if they knew their only means of survival would be the slim chance of being picked up at sea…. Ditching in enemy territory would be a needless waste of planes and highly trained airmen.”
⁷

With two or even four carriers, Genda’s estimate was that the total aircraft available could not haul sufficient bombs and torpedoes to destroy everything. Damage estimates showed that more carriers were needed. The Japanese would have a total of six fleet carriers available in November 1941 when
Shokaku
and
Zuikaku
joined the fleet, albeit with air groups that would be “really green.”
⁸

However, there was competition for fleet carriers: the Operations Section of the Naval General Staff
⁹
felt they needed at least two fleet carriers to support the Southern Advance, especially the invasion of the Philippines, which would be opposed by a significant American air component.

Genda’s conclusion was that the effort should not be made unless all available fleet carriers were thrown into the attack. The Operations Section knew that fighter support would be necessary to support the attacks on the Philippines. The conflict seemed insurmountable.

Eventually, trials with the A6M Zero naval fighter developed fuel conservation techniques that gave the fighter sufficient range to escort bombers launched from Formosa against the main Philippine military facilities at Subic, Clark Field, and Cavite. By lowering engine RPM and leaning out the fuel supply, the A6M Zero’s cruising speed was reduced to 115 knots, but fuel consumption was cut from 35 gallons per hour to 17. This gave the Zero a range of as much as 1,250 nm with an endurance of 11 hours.
¹⁰
This freed the fleet carriers to strike Pearl Harbor.
¹¹

It was the weapon of the samurai that provided the inspiration for the attack. In the repertoire of the sword there is the “one swift stroke,”
Kinshicho-Oken
, where the samurai in one motion pulls his sword from its scabbard and decapitates his opponent, then returns to his original position.
¹²

Japanese Weapons, Naval Air Power, Carriers, and the China Experience

The Japanese in 1941 were leaders in carrier aviation. Their technical development was advanced relative to the other navies and seasoned by combat experience in the China War, a war which was to see the introduction of a new level of performance in naval aviation with the introduction of the monoplane, an all-metal aircraft of unprecedented performance.
¹³

During the war with China, Japanese aircraft carriers ranged along the Chinese coast, launching strikes. When the war moved further inland, the air groups from
Ryujo
and
Hosho
were based inland at Kunda outside Shanghai.
¹⁴
With Japan’s new high-performance fighter, the A5M Claude, and the development of a special looping turn maneuver (a displacement roll) that allowed the Claude to cut inside the turns of enemy fighters, eventually the Japanese gained control of the air.

They also gained an opportunity to test out doctrine and equipment. For example, they learned that long-range, high-altitude and high-speed medium bombers required fighter escort, and that high-altitude bombing was not always devastating, contradicting the beliefs of many Western air power theorists.

Operational experience also revealed weaknesses. Japanese aero engine technology was behind the West in making reliable high-powered engines. As a consequence, and due to a philosophy that enshrined maneuverability and eschewed “defensive” protective features such as armor plate and self-sealing fuel tanks, their aircraft were lightly built. This gave them superior maneuverability and speed and allowed them to carry heavier payloads over longer distances than other nations’ aircraft with comparable engine horsepower.

However, this also made the aircraft susceptible to enemy fire. Japanese aircraft fuel tanks did not include self-sealing inner liners, making them susceptible to leaks and compression vapor explosions when hit, earning the Japanese aircraft the sobriquet of “Ronsons,” the name of a popular cigarette lighter of the era. One aircraft type that was to see service at Pearl Harbor, the D3A Val dive bomber, had a fuel tank under the pilot’s seat.

The Japanese viewed these as acceptable trade-offs. Their emphasis was on offensive capabilities, with defensive capabilities scorned as “not Japanese.” For example, the instructions to the designers for the 12Si carrier fighter competition (that which resulted in the A6M Zero fighter), formulated after the initial Chinese combats in 1937, required no armor protection. None could be provided considering specifications that called for extreme maneuverability, speed, and rate of climb—the Japanese were just not concerned with attributes that might be considered “defensive.”
¹⁵

The Japanese tradition of personal combat, dating back to the middle ages, moved Japanese fighter pilots to chase enemy fighters and engage in dogfights, forgoing the mundane “defensive” task of escorting bombers. Bombers took severe losses in the air war as the fighters pursued personal glory.
¹⁶

These material and doctrinal weaknesses were not considered deficiencies, but just the cost of waging war the Japanese way. Japanese society considered it a great honor to die in combat. Fallen aviators—any fallen warrior—were worshipped as deities. Death in battle was to discard what Buddhism calls the small self so as to serve the greater cause, to live in the great Imperial Virtue, resulting in a readiness for self-sacrifice that was clearly manifested in the Japanese people. Coupled with the Japanese belief that war was an act of will, and that “an iron will can accomplish anything,” these concepts led almost inevitably to aircraft that emphasized offensive capabilities. Defensive characteristics were eschewed almost as if they were an insult to the aircrews’ fighting spirit,
Yamato damashii
.
¹⁷

The Imperial Army took a different direction. Early reports from the war in Europe indicated that armor protection and self-sealing fuel tanks were indispensable. Those features were included in the design of the Ki-61 Tony fighter that began production in August of 1942. It was considered a success, and over 3,000 were produced during the war.
¹⁸

By late 1941 the Japanese had four fleet carriers available, along with one escort and two light carriers, with a total capacity of 378 operational aircraft.
¹⁹
She had five fleet carriers, two light carriers and two escort carriers either under construction or conversion, or undergoing final workups, which meant an additional capacity of 406 aircraft.
²⁰
The light and escort carriers did not have the range to accompany an attack against Pearl Harbor.