by Attack on Pearl Harbor: Strategy, Combat, Myths, Deceptions
“Game” is an unfortunate label, as it connotes an activity with winners and losers. “Chart exercise” is a better title, with less baggage.
Consider a chart exercise where a carrier force is approaching an island for a surprise attack. During the approach the Carrier Force Commander believes he has not been spotted, so, after his strike is launched he retains his CAP (combat air patrol) fighters on deck. Unbeknownst to him, an enemy submarine spotted his force and the enemy launched their own air strike. With no fighter protection aloft, nine hits sink two of the carriers. The lesson is, “Keep CAP aloft at all times.” Notes are made to change the operational order to that effect, and the results recalculated assuming the fighters were properly on station. The exercise proceeds.
Compare this with Prange’s description of the wargame held prior to the Battle of Midway:
… during the table maneuvers, the theoretical American forces broke through and bombed Nagumo’s carriers while their aircraft were away from their mother ships attacking Midway—the very situation which had concerned Ugaki. Lieutenant Commander Masatake Okumiya, the umpire, ruled that the enemy had scored nine hits, sinking both Akagi and Kaga. But Ugaki would not suffer such lese majeste, and immediately overruled Okumiya, allowing only three hits, with Kaga sunk and Akagi slightly damaged. And later, when conducting the second phase practice, he blandly resurrected Kaga from her watery grave to participate in the New Caledonia and Fiji invasions.7
A wargame has many potential paths. Many could result in cancelled operations or major readjustments to a plan, since “no plan survives contact with the enemy.” To prevent wasting time exploring possible (but improbable) rabbit-trails, combat results often have to be readjusted to allow the entire plan to be exercised. What Prange interprets as hubris, as “lese majeste,” and depicts as an inability to stare unpleasant reality in the face, is actually a common and necessary practice in operational planning wargames. With two carriers sunk, the operation would likely be broken off, so continuing down that path would not have been fruitful. The objective of the wargame is not for one side or the other to “win,” but rather to see how to best execute the operation and to ferret out unanticipated factors.
Prange failed to mention that the nine hits were generated by a die roll, not by a pre-calculated deterministic ruling.8 The die roll may have given an extremely improbable result, a statistical outlier, a result entirely appropriate for Ugaki to overrule. On the other hand, Okumiya is said to have been surprised by the move, indicating either that it was unusual to intervene in this manner, or that the change was questionable. Japanese wargaming was hostage to the judgment of flag officers.
Consider another gaming situation. A force takes a route through shallow water and runs into a minefield. Two carriers are lost. There is an alternate route available in waters that cannot be mined. The two carriers are restored to the game, and a note made to change the operational plan to avoid the shallow water. This is not lese majeste, simply the accepted practice of adjusting the course of the action to account for lessons learned.
Prange accepted uncritically comments made by Fuchida that, “If any notable difficulties arose, Ugaki arbitrarily juggled them in favor of the Japanese team.”9 Without a clear understanding of operational wargaming, he did not know to ask questions that might have resulted in a more balanced assessment and a better understanding of what might require Ugaki to make adjustments to the game’s combat results.
Much of this testimony comes from Fuchida. Here, as in many other places, he relates the story in a manner that places others in a bad light and intimates that Fuchida knew better all along. Fuchida was not the impartial witness needed to pass judgments on Ugaki’s decisions.
As the exercise proceeded, Ugaki and his staff should have been noting lessons from the individual encounters and tabulating them to discuss after the game. Japanese culture and manners limited on-the-spot criticism. The results were likely adjusted so the exercise could continue to test the plan. Prange stated that “cheating occurred during the war games for Pearl Harbor,”10 as if it was a schoolyard game with winners and losers. He was oblivious to Ugaki’s responsibility to monitor the proceedings, and, while ensuring they did not stray far from the objective, that of exercising the entire plan.
Similarly, Ugaki “resurrected” Kaga to allow the officers in command of the New Caledonia and Fiji operations to undergo the crucible of simulated battle with carrier support included in their plan. In the real world, Kaga was lost and the New Caledonia and Fiji operations were cancelled. There was nothing to be gained in the wargame by “practicing” cancelling the operation. To exercise its part of the operation Kaga was needed, so Kaga was “resurrected.”
Certainly the games can be criticized. The process of converting game lessons to planning changes appears to be less effective than it ought to have been—it may not have been formalized at all. The usual American practice was to include note-takers capturing all such issues in preparation for discussions afterward; we do not know if the Japanese had a similar formal practice. Their practice was likely more informal, with individual officers installing changes to their parts of the operational order based on their personal observations and discussions with their counterparts.
A trap of wargaming is the assumption of godlike powers by umpires and admirals. Games proceed under conditions that they deem realistic, even if they are based on judgments that others might question. In the Japanese games there were disagreements over some decisions, but the purpose of a chart exercise is to bring such disagreements out into the open for consideration.
The game’s Japanese critics should not be ignored. There were flaws in the game and gaming process, and judgment calls by the umpires and admirals that were questionable. However, the Japanese wargaming effort was more robust, less arbitrary, and more productive than Prange’s interpretation would suggest. Certainly it was not perfect; in the Midway game there were elements of the “Victory Disease” that infiltrated Japanese attitudes and thinking, along with a sense they would win regardless of what the Americans threw in their path.
Victory Disease had yet to taint the environment when Yamamoto held the first of several wargames to examine the Pearl Harbor attack—more the opposite, as most Japanese naval officers were in awe of the magnitude of what they were about to attempt. These wargames seemed genuine, with perhaps some staging by Yamamoto to help socialize acceptance of his plan with other senior officers. They were games to explore operational alternatives, and not merely to put an existing plan to the test. As such there appears to be fewer interventions by senior officers, although there were some rather improbable judgments that, as will be seen, reflected the role the gods were assigned to play.
The First Games
The first of the wargames were played on 16–17 September 1941. The Japanese allocated all four of their active fleet carriers to the striking force. The carriers were spotted before they launched their attack, alerting Pearl Harbor’s defenses. The Japanese strike met heavy resistance from interceptors and AA. Half the strike aircraft were shot down,11 losses on the order of 106 to 127 aircraft (depending on the composition of the strike). Only “minor” damage was inflicted. Counterattacks by US aircraft sank two carriers and damaged the other two. The attack was a disaster.
The next day the game was re-run with some modifications. The plan was modified so that the carriers made a high-speed overnight approach to arrive at the launch point before the American scouts were in the air for their morning search. Surprise was achieved. The strike was judged to have sunk four battleships and severely damage one, sunk two carriers and severely damaged one, and sunk three cruisers, with three cruisers heavily damaged. One hundred and thirty US aircraft were destroyed,12 50 in the air and 80 on the ground. US counterattacks sank one carrier and severely damaged another. While withdrawing, a fortuitous (probably umpire-generated) rain squall screened the Japanese fleet from further damage.13
The attack was deemed feasi
ble, but heavy Japanese losses were expected.14
Details of the game rules and damage assessment formulae, along with details of the composition of the strike, are not known, along with details such as how many B5N Kate bombers carried torpedoes, and what proportion of the D3A Val dive bombers were allocated to hit ships and what proportion were allocated to airfield targets. The D3A Val dive bomber had at this time demonstrated (in training) a 50 to 60 percent hit rate, but B5N Kate torpedo bombers had yet to solve the shallow water problem. Rigorous training in April of 1941 had increased the B5N Kate level bombing hit rate from 10% to 33%.15 But, with the uncertainties in how the Japanese composed their strikes, there is insufficient information to reproduce the calculations for each weapon, and how the stated result was achieved.
The wargame serves as a benchmark to what the Japanese believed an attack with four carriers might accomplish. If the enemy was alerted and had their air defenses ready, the Japanese felt that there would only be “minor” damage inflicted. If surprise was attained, the damage inflicted by the four carriers would be enough to immobilize the main body of the US Pacific Fleet for the needed six months. But only 130 of the estimated 550 American aircraft on the island would be destroyed, leaving sufficient air power for strong counterattacks. Consequently, the risk was deemed high. “At the September war games, even with the umpires bending over backwards in favor of the home team, all had agreed that they must anticipate the sinking of several carriers.”16
Part of the “bending over backwards” perhaps involved the anticipated hit percentages against the fleet. In this wargame, four Japanese carriers accomplished more damage against warships than was accomplished in the actual attack with six carriers.
It may have been that the Japanese saw that the level of effort used in this wargame achieved sufficient damage against the fleet targets, but there were shortfalls in the damage inflicted on American air power. So, when Shokaku and Zuikaku became available, they were pulled into the attack plan, and the bulk of their aircraft was directed to the offensive counter-air (OCA) role.
Another alternate possibility is that the aircraft in the actual strike did not achieve the hit rates and fire distribution expected of them, so the six carriers, in reality, caused less damage then was predicted for the four carriers in the wargame.
Another optimistic assumption was that one A6M Zero was the equivalent of three enemy fighters—when one officer tried to challenge “such stupidity” he received a “sharp admonition.”17
Another Round of Games
Beginning 13 October 1941 another wargame was held on the flagship Nagato, with Yamamoto as host. This time the striking force had only three fleet carriers—Akagi was pulled out at the insistence of the Naval General Staff to support the attack on the Philippines.18
In this game surprise was achieved, but only “moderate damage” was inflicted. How the damage was assessed is again unknown, as is the threshold between “major,” “moderate,” and “minor” damage. The Japanese warships took no damage, but the operation was seen as “less than satisfactory.”19
One might suspect that Yamamoto welcomed the verdict of “moderate damage” inflicted by the three carriers—that is, if he hadn’t set up that outcome—since that usefully established the need for more carriers in the minds of the attending Naval General Staff officers. In addition, the Japanese force escaped without damage, another result that Yamamoto would welcome in his campaign to obtain approval for the attack.20
A few weeks later Yamamoto asked for and got all six fleet carriers.
Not all the discussion was on the expected offensive results of the operation. Many of the planners emphasized bringing the precariously vulnerable carriers back to home waters quickly and safely. The need for repeated attacks against Pearl Harbor did not come up during the wargames, although two of Yamamoto’s planners—Genda and Commander Sasaki Akira, Yamamoto’s Air Staff Officer—talked about the possibilities before and after the exercises. Nevertheless, in front of the flag officers the exercise concentrated on what could be accomplished against the American fleet units in a single strike of two waves, and the costs in terms of aircraft and carriers damaged and sunk.21
Summary
The wargame results established mental models of expected outcomes (cause and effect) in the minds of the attending officers. These models can be summarized as follows:
The possible Japanese losses were daunting—they were losses on a strategic level, losses that could influence the course and outcome of the war as a whole. And yes, there were opportunities for the umpires to inject bias—Admiral Kusaka thought “the results depended too much on the various personalities of the umpires.”22
The Japanese were never ones to allow calculations of material forces (or a roll of the dice) to take precedence over their deeply held belief in the primacy of fighting spirit and the unquantifiable superiority of Japanese crews and equipment. These games were “mere mathematical exercises.” They ignored the factors of luck and divine guidance, factors that the proponents were sure favored the Japanese.23
In spite of the gods’ expected bias, the word that filtered down to the aviators was that they faced a fifty-fifty chance of dying for their Emperor.24
To Yamamoto, whatever the circumstances, whatever the potential for losses, the effort had to be made. He was adamant. The issue went beyond logical argumentation. In an exchange with one of his most intransigent opponents, Yamamoto “put a hand on Kusaka’s shoulder and said with an air of utter sincerity, ‘Kusaka—I understand just how you feel, but the Pearl Harbor raid has become an article of faith for me. How about cutting down in the vocal opposition and trying to help me put that article of faith into practice?’”25
Western readers, grounded in theories of total war based on calculations of material superiority and firepower, might dismiss this approach as something akin to superstition, an outmoded, backward belief system. If so, they have eluded understanding.
In war, there are only three ways to win: by annihilating the enemy, totally incapacitating him, or by eliminating the enemy’s will to fight. The first two are more in line with Western theories of war, but occur in a tiny number of cases historically. Few wars or battles have been won by annihilation or total incapacitation of the enemy. The overwhelming majority conclude when one side decides to quit.
The Western way of war strives for annihilation but accepts the enemy’s surrender well before annihilation. Changing the enemy’s will to fight is a by-product of material losses. Instead, the Japanese recognized the primacy of the will to fight from the outset, striving for means to convince the enemy to quit without requiring overwhelming incapacitating losses to settle the issue. If this could be accomplished, as in the Russo-Japanese War or the Sino-Japanese War, their relatively small country could successfully win against opponents many times their size. Just because their approach did not work in World War II does not invalidate it—it simply demonstrates that the course to winning a war based on the psychological defeat of the enemy must be carefully charted.
Yamamoto sought to induce despair in the volatile American voting public by destroying an inviolate symbol of naval supremacy, the battleship. He was convinced he had taken the measure of a population that was vocally pacifistic. He did not understand that the loudest voices in the American polity may not be the most representative.
Several times after the wargames he reasserted his determination to make the attack, in one instance announcing, “As Commander-in-Chief I have resolved to carry out the Pearl Harbor attack no matter what the cost.”26
CHAPTER FOUR
PLANNING THE ATTACK
Limitations and Constraints
The attack plan was limited by material, force level, and doctrinal constraints.
Carrier Capacity
Eventually, at Yamamoto’s insistence, all six of Japan’s fleet carriers were assigned to the operation. Added to the four large carriers employed in the wargames were the new carriers Shokaku
and Zuikaku, to be completed only weeks before the departure date, barely sufficient time to work up their flight deck crews. These air groups would be “as green as spring grass.” But these aircraft could carry the volume of bombs needed against targets that did not demand high skill levels.
All six fleet carriers provided the planners with 417 aircraft. Spare aircraft were on each carrier, but they were disassembled and crated and would take a day or more to assemble.
As seen in the chart that follows, the numbers of each type of aircraft are nearly balanced, and reflected the normal complement of the carriers.
Tailoring the Air Groups for the Attack
Only three of the Japanese carriers had sufficient range to make the transit from Japan to Hawaii and back without refueling.1 Genda had considered breaking up the normal carrier air groups to preferentially load one type of bomber on those carriers designated for the attack. At one time he considered sending two or three carriers loaded with only fighters and B5N Kates with torpedoes. When the problems with launching torpedoes in shallow water appeared insurmountable, he considered leaving home all the B5N Kates and loading up a few carriers with just D3A Val dive bombers.
Both concepts would require shuffling aircraft and aircrew between carriers, a violation of normal Japanese practice. Aircraft and aircrew were considered a part of the carriers’ complement under the command of the ship’s commanding officer, and not an independent command as in the American practice. This was a decided handicap. Later in the war, in cases where Japanese air groups were decimated, as happened to Zuikaku and Shokaku at the Battle of the Coral Sea, the entire carrier had to be withdrawn from operations until a new air group could be assembled and trained. The American practice of independent air groups that could be assigned to any carrier was much more flexible and effective. For example, Saratoga’s air group was shifted to Yorktown in the days just before the Battle of Midway, and it was operationally effective in a matter of days.2
