Attack on Pearl Harbor (18 page)

Nine aircraft at 20-second intervals would make for a three-minute attack. If four
chutai
went in one at a time against the four shipyard targets (the longest queue, the other cruiser targets being far enough apart that they could be attacked simultaneously), the attack would have lasted 12 minutes. This would mean a relatively drawn-out attack, and would allow the defenders to concentrate their defensive fire against each succeeding attacker, but it would minimize mutual interference in the bomb runs and allow some command and control over the distribution of aircraft to each target.

Approach: Time on Target (TOT)

(9) Japanese Aircraft Approach Routes, From
Campaigns of the Pacific War

The first and most elementary planning consideration ought to have been simultaneity. In the first wave, while torpedo bombers were attacking the fleet at Pearl Harbor, dive-bombers and fighters were to attack Hickam, Wheeler, and Ewa Fields. It was within the technology of the time for the first-wave aircraft to arrive over every target area simultaneously, called a Time on Target (TOT) strike. This would eliminate any chance that one defending area could flash a warning to other areas.

If simultaneous arrival over all the target areas could not be achieved, the attackers would want the Pearl Harbor group to go in first to allow the torpedo bombers to attack before the defenses were manned.

The approach was planned to come down the center of the island. North of Pearl Harbor the two torpedo groups would split to go to their initial points (IP) east and west of the harbor. The distance to their IPs would be nearly identical, so a “nearly simultaneous” attack by the two torpedo groups was planned.

A simultaneous TOT for all formations would not have been hard to plan or achieve. There were several prominent geographic points on the northern coast of Oahu that could have provided navigational starting points. The formations that had the furthest to go would fly directly to their target, while the other formations could orbit in place and depart timed so that all the formations would arrive at their targets simultaneously. This “time and distance” exercise is one routinely inflicted on pilot and navigator trainees on the way to their wings, and was within the technology of the period.

To place this in perspective, General Quarters could be set on a US battleship, with all AA guns manned and ready, in eight to ten minutes. “Ready” guns could be firing in less than one minute. To qualify as “all in the same instant,” the attacks should all be initiated before General Quarters could be set.

There is a clue as to why the Japanese neglected to provide for TOT attacks. Many Japanese aviators commented on the speed with which the American defenses responded, and the intensity of the anti-aircraft fire. One pilot testified that Japanese sailors would never have been so quick. The Japanese mirror-imaged their expectations for the speed of the Americans’ defensive response based on how they would expect their own forces to react. They simply did not believe that their enemies would respond so promptly, and consequently saw no need to time their arrivals with any precision.

Overall Impression of the Plan

The plan had significant shortfalls. It was not state of the art for the period, did not employ all the available tactics and techniques, and failed to anticipate what should have been obvious problems. It did not employ the combined arms approach that these same air groups practiced in attacks against battleships at sea. Either the plan or the planners themselves were remarkably inflexible, as there were no built-in decision points to respond to changing conditions or developing intelligence. As will be seen, the plan was not adjusted to address the problems revealed in rehearsals. The allocation decisions and target prioritization for all three types of aircraft are questionable. If the Americans had been in their usual level of readiness and reacted to the detection of the Japanese strike while it was inbound, it is likely that the torpedo attacks would have been a complete failure.

Overall, as a plan touted as “brilliantly conceived and meticulously planned,” the attack on Pearl Harbor does not stand up well under close examination. Additional problems were revealed when the plan was executed.

Planning Deficiencies vs. Doctrinal Deficiencies

Planners are guided by the doctrine under which their forces are trained and operate. It is difficult at times to determine if deficiencies in the planning were due to planning oversights or doctrinal constraints. Certainly in a plan that matured over a ten-month period there was ample time to adjust and train to a new doctrine, if that was needed.

The Japanese planning process cannot be held to modern standards. Pre-war staffs were not capable of the same kind of structured planning that modern military forces employ. It would have taken a particularly brilliant planner to make the conceptual leap to, for instance, break the stovepipe structure of planning by aircraft type and take on a combined arms approach. Failures that came from a deficient planning structure ought not to be considered a failing of the officers involved in the planning.

There were cases where the planners recognized a need and adjusted doctrine—for example, they reduced the level bomber formations from nine to five bombers. In other cases, doctrine or the unique Japanese way of war blinded them to things that were needed, such as the failure to use the fleet’s combined-arms SEAD aircraft tactics in the torpedo attack against the battleships. Another example is the failure to restrain the fighters from their independent attack role in order to have them provide cover for the torpedo bombers all the way to the target.

Doctrine is a good and necessary thing, but it should be a tool, not a set of blinders inhibiting planners from creative measures to solve problems. The Japanese did not have a reputation through the war of applying creative solutions to problems. They adjusted doctrine rarely, and then reluctantly, usually only after a significant defeat forced deficiencies to their attention. This study can only note where doctrine led to poor decisions or succeeded in providing good decisions, and where the planners were able to overcome their conditioning to arrive at creative solutions for the unique problems associated with the Pearl Harbor attack.

Training

The Japanese dispersed their aircraft to many different airfields for their training. They were concentrated by type at each field, so there was no cross-pollination between dive-bombers, level bombers, torpedo bombers and fighters. Torpedo bombers, for example, were split between Kanoya and Omura air bases. Their training started on 31 September 1941. Six weeks lay ahead of them before the first of the carriers,
Hiryu
, departed Kyushu on 18 November en route to
Kido Butai’s
marshalling rendezvous in the Kuriles.

The
Hikotaicho
(air group commanders) were responsible for training the units. Fuchida had the responsibility for the level bombers attacking the fleet, Shimazaki the OCA (offensive counter-air) level bombers, Lieutenant Commander Takahashi Kakuichi the OCA dive-bombers, Egusa the dive-bombers going after fleet targets, Murata the torpedo bombers, and Lieutenant Commander Itaya Shageru the fighters.
¹

The training was intensive, sometimes extending to several flights a day. Some of the dive-bombers’ training was made more difficult by remote bombing ranges, requiring long flights which wasted time and fuel. The newer aircrews, of whom there were many, spent a lot of time in basic training and getting qualified to operate off carriers.

Time was spent in night training. Early plans were for the first wave of the strike to launch prior to dawn. This idea was cancelled when the
Zuikaku
and
Shokaku
aircrews did not attain the needed proficiency. The night training time was wasted.

Fighter training consisted mostly of fundamental airmanship skills such as formation flying. Postwar, veterans did not mention training in strafing techniques; evidently the fighters expended little ammunition at gunnery ranges.

Conspicuously absent was any combined training. Fighters did not train with the bombers to learn how to escort their approach or to protect them during their bombing runs. The attack was decomposed into a set of individual missions that were to be executed discretely, without reference to what other aircraft were doing. Combined arms and mutual support was not in the Japanese mindset.

Rehearsals

When possible, preparations for any large or complex military operation include a rehearsal. Rehearsals provide practice for the participants and an opportunity to test the plan. In the best rehearsals, all of the participants are informed of their role, and a time and location is selected that best emulates the expected conditions, geography, and terrain. Afterwards, a critique is held and adjustments are made to the plan.

The first rehearsal was held on 4 November. The carriers were positioned 200nm off Kyushu, and launched their attack against the naval air station at Saeki and the Combined Fleet at anchor. There was no attempt to emulate the geography or the restricted lines of approach the torpedo bombers would encounter at Pearl Harbor. The torpedo bombers went in first, followed by the level bombers. In a second wave, level bombers simulated striking Saeki Field and dive-bombers attacked anchored fleet targets, particularly the carriers
Akagi
and
Soryu
.

Afterwards, notes from Genda, Fuchida, and other staff officers were collected and reviewed. The approach to the target and the general deployment was faulted, as was the time required for rendezvous. Only 40% of the torpedoes leveled off at the correct depth, some dipping below 60 feet.

Another rehearsal was held the following day. This time a group of defending fighters intercepted the attackers about 80nm north of the target, resulting in an air-to-air battle. Afterwards, Genda faulted the accuracy of the level bombers, and Fuchida became concerned that the battleships closest to the attackers received the brunt of the attack.
²

Rehearsals must be gauged more by the problems they expose rather than their successes. Many deficiencies were likely corrected but not placed in the historical record. It is impossible to judge the significance of the resulting changes. However, significant problems slipped by that were to have a considerable impact on the course of the attack.

The problem of the crossing torpedo attack routes was not revealed. There is no evidence that the target ships were anchored in any arrangement simulating that to be encountered in Pearl Harbor, so issues of deconfliction could not be explored. The problem of simultaneity for the torpedo attack was not exposed. The Combined Fleet was anchored at Ariake Bay, which is a wide anchorage without the restricted approach routes found at Pearl Harbor. Likely the torpedo bombers went in waves, as was doctrine in a normal attack, and so this problem was not exposed. Moving from the approach formation into the torpedo bombers’ long “string” formations was not tested.

The fact that only 40% of the torpedoes functioned as desired was worrisome, and it appears that the planners concentrated their attention on this worrisome development. An equivalent rate during the actual attack would result in only 16 torpedoes with normal runs, and likely fewer hits than that. That this problem should be revealed so late in the process is remarkable, particularly considering that the shallow water problem was known from the outset of planning ten months before. This stimulated a flurry of corrective actions. Over the next few days the torpedo bombers tried out new techniques and raised their hit rate to 82 percent, a cause for jubilation.

But the distraction of the torpedo bombers’ problem likely overshadowed other corrective measures that were not addressed. For example, the problem of poor attack distribution was not corrected.

There appeared to be no feedback from the troops—the aviators who were actually to deliver the attack—to the decision makers. At least, there was no mention in the standard accounts that the fleet aviators provided feedback to Fuchida and Genda. At this point the
chutai
leaders had been informed of the objective, but the rank-and-file aviators had not. How much useful feedback was lost by continued secrecy? This was likely a systemic problem with the Japanese system. Most Japanese aviators, including most of their pilots, were not officers but enlisted personnel. Culturally there was not a great deal of communications up the chain of command—officers decided, and enlisted men executed.

From training through rehearsal there were several noteworthy deficiencies. Each of the aircraft types had trained separately for their individual missions, flying out of separate air bases. There appeared to be little desire for combined-arms training. Types were not coordinated in any way other than in the attack sequence. There was no mention of wringing out command and control and communications problems—perhaps such problems did not surface because doctrine levied no real command and control and communications requirements on the attackers. The aviators likely were so accustomed to seeing themselves as individual samurai warriors that they felt no need for a higher level of control. Security was closely maintained—prior to departure only one group of fighter pilots and the senior bomber command aviators were informed of their objective.

A better rehearsal might also have surfaced two other issues. There was the potential problem of the rising sun in the eyes of
Soryu
and
Hiryu
torpedo bombers assigned west-to-east attack routes. Aircrews would need to classify their targets before committing to their run, but sun glare could interfere.

Rehearsals should illuminate contingencies—the “what if” issues. Some important and specific “what ifs” were: what if the carriers were not in port, what if surprise was not achieved, and what should the fighters do under various situations? The loss of surprise, the presence of torpedo nets, and whether the carriers would be in port were discussed during the transit, but discussions do not have the problem-illuminating potential of actual practice.

All contingencies for the bombers were “solved” by assuming that the aircraft commanders would be able to choose their targets carefully and accurately. This was a great deal of responsibility to place on the shoulders of the many junior aviators.

Up until this point the plans all assumed that surprise would be achieved. Curiously, even a rehearsal with defending fighters intercepting the strike force did not prompt any thoughts that the real attack might have to go in without the cover of surprise. It is perhaps a measure of the work overload on Fuchida and Genda that these thoughts were not triggered until several days later, by Yamamoto himself.

Overall, the rehearsals proved their worth by revealing the shortfall in torpedo delivery technique, and the last-minute solution of the torpedo delivery problem saved the operation. However, in other areas, the critique and corrective actions that ought to have come from the rehearsals were sadly deficient.

Briefings

After
Kido Butai
departed, Japan the aircrews were briefed. A large-scale model of Pearl Harbor was used, constructed on the same scale as the harbor would be seen from 10,000 feet. It was appreciated as a beautiful work of craftsmanship. Fuchida briefed large groups and met with smaller sections to brief their particular roles, and afterwards was hoarse after a day of talking. Likely he flew from carrier to carrier to speak to all the aviators.

Before the attack Fuchida claimed that he had a case of the nerves. He feared his level bombers would not be successful. And the presence of anti-torpedo nets would leave the responsibility for a successful raid in their hands. So, in his briefings to the aircrews, Fuchida “stressed the importance of mass concentration against a single target.” He emphasized that minor damage, even to every enemy ship, would add up to an unsuccessful mission.
³

However, on another chart that he constructed for Gordon Prange, Fuchida showed four lines of approach that were briefed to the level bombers, with the weight of the attack evenly distributed. Three of the mooring points were those occupied by
Arizona, Tennessee
, and
Maryland
on the day of the attack. The fourth was
Pennsylvania’s
usual berth along 1010 dock. The bombers were to attack one group at a time, aiming at ships in the order listed on the chart. After the first four groups attacked ships one through four, the next four groups would repeat against the same four ships. Only double-berthed ships were to be attacked. If these instructions were followed in the actual attack, three groups would have attacked
Maryland
and
Arizona
, and four against
Tennessee
.

Including Pennsylvania’s berth at 1010 dock is curious, because the flagship rarely double berthed with another ship and thus ought to have been accessible to torpedoes. It could be that the prestige of sinking the fleet’s flagship played a role in this decision.

Fuchida’s instructions are inherently contradictory, a point that has eluded most historians. How could Fuchida give instructions for an even distribution of attacks and at the same time “stress the importance of mass concentration on a single target?”

Which approach was correct? It depends upon the model of bomb damage that is used. If it is believed that damage is cumulative, that each hit contributes a quantum of damage, and crippling damage is the result of cumulative damage from each hit, then concentration is the proper approach. If it is believed that damage is stochastic, that each bomb has a certain percentage chance of hitting an engineering space or a magazine, and a single such hit can cripple or sink the ship, then distribution is the proper approach.

Fuchida likely never directed his level bombers to concentrate on a single target. He made this statement postwar. Claiming that he directed a concentration of bombers on a single battleship might have been a way for him to garner some reflected glory from the explosion that destroyed
Arizona
, along the lines, “I was afraid the level bombers would not sink anything, so I directed them to concentrate on a single battleship, and as a result of my good advice the
Arizona
blew up.”

Fuchida had a personal stake in the performance of the level bombers. He was a level bombing specialist at a time when many Japanese aviators considered eliminating that technique from the carriers’ repertoire due to low hit percentages. He also participated in the attack in a level bomber. There is no conclusive evidence on one side or the other to confirm Fuchida’s testimony—only the recognition that his statements are contradictory.

The torpedo bomber aviators were also briefed on their group’s targets, either along the carrier moorings or Battleship Row. They were given considerable latitude to choose their targets. One torpedo pilot in a postwar interview related how he flew over the harbor “looking for a target”—not looking for
his
target.

The 16 carrier attack aircraft assigned to the carrier moorings were warned that the carriers might not be in port. Had a single carrier been present, it is very likely that one full string of eight bombers, and perhaps all 16, would have attacked her. They were also warned that the demilitarized battleship
Utah
occasionally used the carrier moorings. They were instructed not to waste a torpedo on her.

In the briefings, Fuchida emphasized that aircrews were to take the initiative in selecting alternative targets, and were to break off attacks on ships that were obviously destroyed.

The briefings sent a number of mixed signals to the aircrews and had several inconsistencies.