by Attack on Pearl Harbor: Strategy, Combat, Myths, Deceptions
After the war began in 1939 there were hints of air power’s potential. The British air raid on Taranto that sank three Italian battleships provided a significant nudge in the ribs, but there were also many cases where ships survived air attacks unscathed. The battleship could not be ruled as obsolete after two German battlecruisers gunned down a British aircraft carrier, taking no damage themselves. By late 1941 there was still much to be discovered, much still in flux, no conclusion yet possible regarding the relative effectiveness of aircraft v. ships.
Regarding the Pearl Harbor attack, care must be taken when pointing out what might be seen as errors or omissions on the part of the Japanese planners or participants. These warriors were breaking new ground without the benefit of the knowledge available now, or the perspective of experience from the many air battles of WW II. The state of the art at that flash of time must be kept in focus. This is difficult. Because of the rapid rate of change, the front-line operational tactics, techniques, and procedures outstripped written doctrine. Doctrine might not even exist on paper, with the current “best practices” only in the minds of the aviators. This study includes some detective work, along with an inevitable element of informed speculation.
One cannot but retain great respect for those challenged to plan and execute the attack, with no precedent to guide them and many technical and tactical problems to overcome. Such respect, however, should not deter a full critical analysis, pointing out where they succeeded and where they failed. This contributes to a better understanding of the combatants, making the War in the Pacific more comprehensible. Analysis can also help reveal the thought processes and mindset the Japanese brought into the battle, and what they took out of the experience.
Mental Models, Cultural Factors and Processes
One of the most important things a commander must be able to do is have an idea of the range of probable results when given combinations of forces engage. He must do this to decide if an engagement is worthwhile, if a given force can defeat the enemy.
This mental process is accomplished by an (often subconscious) application of the commander’s mental models of engagements, models that are developed during his training and over his experience in the service, or perhaps from his perception of his luck, destiny, and place in the pantheon. In addition to being predictive, these mental models act as filters to the data presented to the commander. Things that agree with the preconceptions the commander carries into battle will be seen and registered and considered; those that do not agree can be rejected as invalid and not cognitively processed, can be ignored, or can be rapidly passed over as unimportant in the press of events, in what is known as confirmation bias. The preconceptions a commander carries can also alter his mental condition. Data received that does not agree with the preconceived mental model can cause mental discomfort, agitation, distress, confusion, and a reduced capability to make good decisions, a condition known as cognitive dissonance.
These mental models can be seen as valuable tools to predict the future, or as miserable baggage getting in the way of an accurate assessment of reality. It is important to understand the mental models that a commander has stocked in his mind going into combat. The effects and consequences of some of these pre-conceived mental models can be observed in the course of the Japanese raid on Pearl Harbor. A detailed analysis provides clues regarding the respective commanders’ mindsets, attitudes, and expectations that would influence future decisions.
(1) Chart of Pearl Harbor, 7 December 1941
CHAPTER ONE
STRATEGIC AND OPERATIONAL SETTING
Early Rumblings
An attack on Pearl Harbor as an opening move in a war between Japan and the United States was not a new or unusual concept in Japanese military circles.
The Japanese Navy had a tradition of opening wars with surprise attacks without a formal declaration of war. This was exemplified by their attack on the Russian fleet at Port Arthur, delivered two days after breaking off relations with Russia and two days before their formal declaration of war in the Russo-Japanese War.1
In 1927 Kaigun Daigakko, Japan’s naval staff college, wargamed an attack on Pearl Harbor by two carriers, one of which was lost. That same year, Lieutenant Commander Kusaka Ryunosuke, later as a Rear Admiral to serve as the Chief of Staff of the Pearl Harbor attack force, presented lectures on an aerial attack on Pearl Harbor.2 The following year, Yamamoto Isoroku, a captain who was to rise to command the Combined Fleet, in a lecture at the Navy Torpedo School, said “In operations against America, we must take positive actions such as an invasion of Hawaii,”3 and discussed striking Pearl Harbor. The subject was examined anew in “A Study of Strategy and Tactics in Operations against the United States,” a 1936 Naval Staff College analysis which suggested that Japan should open the war with a surprise attack on Pearl Harbor.4
On the civilian side, between 1910 and 1922, books about imaginary wars were in vogue. After a lull in the late 1920’s, there was an unprecedented outpouring of these books after the London Naval Conference and the Manchurian Incident of 1931, when Japan replaced Russia as the dominant power in South Manchuria. In 1934 alone at least 18 such books were promoted in magazines and newspapers, describing a future war with Russia, the United States, or both.5 Japanese authors such as Hirata Shinsakyu used a pre-emptive attack against Pearl Harbor to begin fictional depictions of war between Japan and the United States.6
Similar attacks were postulated by American and British authors as early as 1909.7 Novelists Ernest Fitzpatrick in The Conflict of Nations and Homer Lea in The Valor of Ignorance depicted Imperial Army soldiers arriving in the Hawaiian Islands as immigrant workers, wiping out the American garrison in a surprise attack, and proceeding to invade the American mainland.8 Bywater’s The Great Pacific War, written in 1925, had the US Asiatic Fleet hit by a surprise attack at Pearl Harbor to open the war.9
One curious aspect was that in many of the Japanese novels the Japanese were defeated, while many American novels had the Americans ignominiously booted out of the Pacific. “Rouse the populace by describing the horrors of defeat” was the message of this genre, predicting disaster if actions were not taken to forestall the threat.
The critical nature of Hawaii was well understood. Pearl Harbor was America’s central position in the Pacific, situated 2,074 nautical miles (nm) from San Francisco, 2,200nm from San Diego, 5,000nm to the Philippines and 3,350nm from Tokyo. First established as a U.S. naval base in 1908, it had been the headquarters of the Pacific Fleet since 1940, a crucial repair and logistics facility, and a vital link in the sea and air lines of communication between the United States and the Philippines. It was the ideal springboard for an American counterattack against Japan and the last line of defense before America’s mainland. Hawaii was considered by the Japanese as part of their Greater East Asia Co-Prosperity Sphere, and portrayed as a legitimate object of Japanese expansion—160,000 of its 400,000 population were doho, or ethnic Japanese, presumed to be yearning for reunification with their Japanese roots.10
Pearl Harbor and Oahu were developed as major bases, with the US Navy taking advantage of Hawaii’s good weather for training. The Pacific Fleet used raids on Pearl Harbor as a component of several Fleet Exercises from 1928 on.11
Japanese Naval Strategy in the 1920s and 1930s
Under the terms of the Washington Naval Treaty, Japan’s fleet of battleships was limited to 60% of the tonnage allocated to America and Great Britain. A disparity of forces was something the Japanese had overcome before. At the beginning of Japan’s war with China in 1894, the Japanese had fewer and smaller ships, on aggregate less than two-thirds of the Chinese tonnage, but they prevailed on the strengths of better gunnery and better tactics. In the Russo-Japanese War the Japanese again began as the weaker side, with half the number of capital ships and one-third the tonnage, and again they emerged victorious.12
With this heritage the Japanese were confident they could develop a strategy to defeat the United States. Two as
sumptions were central in their strategic planning. First, they believed that an attacking fleet required twice the combat capability of the defending fleet in order to prevail. This was to them confirmed by the travails of the Russian Baltic Fleet, which traveled halfway around the world only to be destroyed in the famous battle of Tsushima, the first defeat of a major Western naval force by an Asian navy.
Second, they believed that combat power was the square of the size of the force. This concept was similar to Frederick Lanchester’s modeling of air-to-air battles from the First World War, although the Japanese likely paid more attention to the writings of Rear Admiral Bradley Fiske, who worked out similar mathematical relationships. Fiske also advocated wargaming as a means of working out tactical and strategic problems in advance, a practice the Japanese embraced with enthusiasm. Thus, by squaring the proportions of force, the 10:6 ratio required by the terms of the treaties became 100:36 in terms of combat power, almost 3 to 1, which the Japanese viewed as sufficient for an attacking force to defeat them.13
To win, the Japanese had to change these odds. These assumptions would come into play later in their justification for the Pearl Harbor attack.
The Japanese strategy called for luring the American Pacific Fleet from San Diego out to the Western Pacific, where it would be defeated in a decisive battle. According to Agawa:
…the orthodox plan of operations called for the navy to throw its strength first into an attack on the Philippines. Then, when the US fleet came to the rescue and launched the inevitable counterattack, the Marshalls, Marianas, Carolines, Palaus, and other Japanese mandates in the South Pacific would be used as bases for whittling down the strength of the attacking American forces with submarines and aircraft so that finally, when they had been reduced to parity with the Japanese forces or even less, they could be engaged in a decisive battle in the seas near Japan and destroyed. This was much the same concept as underlay the Battle of the Japan Sea in which, in 1905, Japan had taken on and annihilated the Russian Baltic Fleet off Tsushima.14
The Japanese would invade the Philippines to secure their sea line of communications to the southern resource areas, and as a means to lure out the American fleet into an immediate movement to relieve the islands.15 The Americans would concentrate their warships to protect the large numbers of oilers, supply ships and auxiliaries needed to support the move. As this huge fleet steamed west a battle would develop, in several phases over perhaps several weeks.
In the first phase Japanese submarines, some uniquely equipped with search planes, would locate and track the American Fleet. The submarines, faster on the surface than the American battleline, would converge and deliver repeated attacks. Japanese long-range medium bombers based out of the Mandates would further bleed the American fleet. This was called “The Strategy of Interceptive Operations.”16
Contact between the surface ships of the two fleets would initiate the second phase. Japanese cruisers and destroyers would launch a series of night attacks, firing massive volleys of 120 or more long-range torpedoes, 25% of which were expected to hit. The Americans were expected to suffer heavy losses that would shatter their morale.
In the final phase, the Japanese battleline, now equal or superior in strength to the Americans, would complete the destruction in a long-range gun battle, using their superior speed to isolate portions of the American fleet. The Japanese expected this final battle to be decisive, leading to a negotiated peace. The Americans would be forced to acknowledge Japan’s dominant position in the western Pacific and Asia. This was Zengen Sakusen, or “The Great All-Out Battle Strategy.”17
This basic strategy became fixed in the minds of the Japanese Navy General Staff, changing little between 1925 and 1941. In 1936 Great Britain was added as an enemy. However, up through 1940, while American territories in the western Pacific were to be invaded and taken, and in spite of the popular exhortations of the novelists, the Naval General Staff’s Concept of Operations never considered Hawaii as a target.18
The Japanese expected to win through better tactics, better weapons, and higher-quality ships and personnel. Their training was intensive and realistic, often eschewing safety precautions: for example, destroyers practiced torpedo attacks at night and in poor weather at high speed, and had some dreadful collisions. During 1938 to 1940 training was particularly intensive, “as though a major war were in progress.” The stakes were high. For example, a new exercise was introduced where the fleet would enter harbor at night without illuminating the ships’ running lights, a risky undertaking. Should an error cause damage to one of the ships it was possible that the officer in charge would be “obliged to commit ritual suicide.”19 Night bombing attacks were practiced with an emphasis on realism. Searchlights from air defense sites would dazzle the pilots, which caused mid-air collisions and the loss of aircraft and lives. After several such incidents the program was questioned, but ultimately training continued as before. The losses were accepted.
Japanese ships were customized for the specific conditions and location of the expected encounter. The final decisive battle was to occur near home waters, so Japanese ships characteristically had only moderate endurance and low habitability and were expected to be able to operate largely out of their home ports. Hull strength, damage control fittings, stability, and other attributes were sacrificed to attain very high top speeds and very heavy armament. Ships were loaded with weapons far out of proportion to the ship’s displacement.
Sometimes the designs pushed armament loads too much. In 1934 the torpedo boat Tomozuru capsized in heavy seas. The design had to be revised, and the stability margins in other classes re-examined. Many ships were required to take aboard hundreds of tons of ballast to lower their center of gravity.
An attack on Pearl Harbor was not included in Zengen Sakusen. Japanese ships generally did not have the fuel to sail from Japan to Pearl Harbor and back. Since the decisive battle was to be fought near Japanese home bases, there was no imperative to develop underway replenishment methods or to build the specialized auxiliaries needed for remote operations.
The advent of the Southern Operation—the plan to capture the petroleum and resource producing regions of Malaya, Borneo and Java—delivered a shock to the Japanese Navy. Now the fleet was expected to take the offensive thousands of miles away from Japanese home waters, capture enemy territory, and hold it. Outlying areas that were expected to be lost in the course of the Interceptive Operations now were to be held.
The Naval General Staff adapted. The Decisive Battle was moved thousands of miles from Japan, before the Southern Resource Areas could be recaptured. Zengen Sakusen, the darling of the Naval General Staff, still applied.
However, with a change in command of the Japanese Combined Fleet came a change in the Fleet’s concept of how to open the war. The new commander was Admiral Yamamoto—the same Yamamoto Isoruko who had lectured on attacking Pearl Harbor in 1928. His thoughts returned to Pearl Harbor, considering the idea of a pre-emptive attack against the American Pacific Fleet employing Kido Butai, the concentrated carrier striking force. “It took someone in the Japanese naval high command of his position, stature, and heretical outlook to make the argument at the highest levels, and then push it through to activation.”20
To Attack Pearl Harbor: Yamamoto’s Objectives
Yamamoto believed that Japan should “fiercely attack and destroy the US main fleet at the outset of the war, so that the morale of the U. S. Navy and her people” would “sink to the extent that it could not be recovered.” He went on to say, “We should do our very best at the outset of the war with the United States… to decide the fate of the war on the very first day.” More ominously, he predicted that “If we fail, we’d better give up the war.”21
With the spectacular success of the Pearl Harbor attack, such fatalism has been discounted. Yet, Yamamoto himself—“short, plump, superstitious, a womanizer and a passionate gambler”—expressed that “half calculation, half luck” played a major role in his d
ecision making.22
What were these calculations? How much luck did the ardent poker player need? What did Yamamoto expect to achieve, and at what cost? Addressing these and similar questions will help reveal whether the attack was a deservedly successful, finely calculated operation, or a spin of the wheel.
Objective #1: Sink a Battleship
The first objective was, simply, to sink a battleship.
Yamamoto, lauded as the “Father of Japanese Naval Aviation,” believed that battleships were “white elephants.” He opposed the construction of the superbattleship Yamato, echoing his aviators that “the three great follies of the world were the Great Wall of China, the Pyramids, and the battleship Yamato.”23
However, he also believed that the battleship was fixed in the minds of the American public as the sine qua non of sea power, and that the battleship had “intangible political effects internationally as a symbol of naval power.”24 Should the Japanese succeed in sinking one of these behemoths, Yamamoto expected the Americans to be so shocked and demoralized that their will to continue the war would submerge with the shattered battlewagon. This, Yamamoto believed, would lead to the same ending as that achieved by Togo after the Battle of Tsushima: a peace conference leading to a negotiated end to the war.
Yamamoto concentrated on sinking battleships; carriers were not part of his picture. His utterances about sinking carriers were largely an afterthought.
At one time in the planning process, Yamamoto remarked, “Since we cannot use a torpedo attack because of the shallowness of the water, we cannot expect to obtain the results we desire. Therefore, we probably have no choice but to give up the air attack operation.”25 The shallowness of the water would not have prevented dive bomber attacks against carriers, which the Japanese believed could be destroyed by four 250-kg GP bomb hits, but torpedoes were required against battleships. He would cancel the attack if he could not torpedo battleships, even if there were carriers that could be sunk by dive bombers. Yamamoto’s objective was the battleships, not the carriers.