Attack on Pearl Harbor (24 page)

The last reason cited in
Lessons
was most significant: “It is human nature to seek an easy-to-attack objective.” Twenty-one torpedoes were launched at
Oklahoma
and
West Virginia
, over half the available torpedoes, because the attack planning and briefing failed to give workable guidance on target selection. Over half the 40 pilots, anxious to be individually successful, took the easiest approach. Some reported that they aimed at
Oklahoma
or
West Virginia
because they were taking heavy fire and they wanted to get their weapon in the water before they were shot down. The geography of the approach would naturally funnel the attack towards the southern end of Battleship Row. The aviators should not be faulted, but rather the planners indicted for their failure to anticipate the problem, particularly after the problem of overconcentration was revealed to them during the rehearsals.

Chart 11 shows the attack paths actually used by the torpedo bombers. The circled numbers show the number of hits and the number of torpedoes that were launched on each route. Most of the Japanese pilots opted for the less technically demanding approach, down the loch past the shipyard to establish altitude and airspeed, and a final turn to line up on the target. There are no eyewitness accounts indicating that the near-impossible hop over the supply base to hit the northeastern part of Battleship Row was even attempted. The route taken by one pilot over the Navy Yard to hit
California
from the south is from the pilot’s testimony and American witnesses.

These problems were an early demonstration of the inflexibility in planning and execution that was to bedevil the Japanese throughout the war. Ugaki, Yamamoto’s chief of staff, saw this when his staff would present him with plans that did not provide alternative courses of action. “I can’t help feeling that they are considering the war too rigidly,” he recorded in his diary. “They don’t seem to know that [war, combat operations] depends largely upon momentum and chance.”
¹⁶

The whole idea of a prioritization scheme was counter to Japanese psychology. What young Japanese warrior, filled with the spirit of
Bushido
, in this most important battle in Japan’s 2,600 years, would want to come home and report, “I attacked a secondary target”?
Not one Japanese pilot dropped a torpedo against what he believed to be a secondary target
.

Torpedo hits on battleships

The attack against Battleship Row resulted in a skewed distribution of hits. Twelve hits were scored on only two of the battleships. The remaining three torpedo hits were scored on
California
(two hits) and
Nevada
(one hit).

There was a bogus report of an additional hit reported on
Arizona’s
bow, first reported at the time of the attack and recently repeated in the television program
Killer Subs in Pearl Harbor
. This claim is not substantiated by any material evidence. When divers inspected
Arizona’s
hull they found no evidence of a torpedo explosion, or even a dent from the impact of a dud. This was reported in
Arizona’s
War Damage Report,
¹⁷
and verified by many subsequent inspection dives, including a detailed mapping of the hull after the war and periodic hull inspections by the National Park Service interested in containing oil leaks. The official final analysis of the loss of the battleship unequivocally stated, “It therefore can be accepted as a fact that a torpedo did not hit
Arizona
.”
¹⁸

If a torpedo had exploded against
Arizona
, the repair ship
Vestal
would have suffered the same underwater damage as did
Oglala
when
Helena
was torpedoed. She did not.

In addition, an aerial photograph of Battleship Row just prior to
Arizona’s
magazine detonation does not show any oil leaking from
Arizona
(the outboard fuel tanks were filled to 95% capacity in the area of the alleged hit), or any of the characteristic ripple of shock waves in the water associated with torpedo hits. Finally, no torpedo bomber claimed to have attacked
Arizona
.

Surprisingly, this has become an issue in another historical question, the theory that a midget submarine penetrated the harbor. This will be discussed further in
Chapter 11
.

The reported torpedo hit on
Arizona
was actually the plume from an 800kg AP bomb dropped by a
Hiryu
level bomber.
¹⁹

Surprise

Surprise magnified the results of the attack. If the US ships had not been surprised, and had simply been in a proper condition of material readiness with Zed set and damage control teams manned and ready,
California
and perhaps
Nevada
could have shrugged off their torpedo hits and remained afloat; fire damage to
Tennessee
and
West Virginia
might have been better contained;
Oklahoma
might have had a shot at counterflooding, and might have remained upright if the void covers on her torpedo defense compartments had been properly closed.

Lack of Reserves

The uneven distribution of hits points to another flaw in the plan: a lack of reserves. The plan’s concept was to have all the torpedo bombers attack “nearly simultaneously.” By executing the attack in strings the leaders had no way to control the distribution of weapons. If a few torpedo bombers had been held in reserve, the commanders could have directed them against targets needing additional attention. Some of the overkill on
Oklahoma
and
West Virginia
could have been sent against
Nevada
and
California
, or against cruisers. An attack by a reserve group of torpedo bombers could have been covered by a SEAD group of dive-bombers and fighters, or even strafing runs by D3A Val dive bombers that had expended their bombs against Ford Island.

Success Achieved by Eleven Torpedo Bombers

With better execution the results would have been considerably worse for the Pacific Fleet. Against the 82.5% torpedo hit rate achieved by the Japanese at the end of their training program they achieved only 19 hits (48%).

Discounting the overkill on
Oklahoma
and
West Virginia
, and the torpedoes wasted on
Utah
, there were only thirteen torpedo hits that contributed to achieving the attack’s mission—
Raleigh
(1),
Helena
(1),
Nevada
(1),
Oklahoma
(4),
West Virginia (4)
, and
California
(2). That is an effectiveness rate of 33%, a figure well under Japanese expectations, and less than half the rate achieved by the British at Taranto in an attack executed at night in a harbor festooned with balloons and torpedo nets. Considering that
Raleigh
was hit by a torpedo aimed at another ship, and
Helena
was attacked under the assumption she was a battleship, the number of accurate attacks is reduced to eleven. The effectiveness of the aircrews in recognizing and attacking appropriate targets and accurately delivering their ordnance is reduced to 28%.

Calling this “brilliant” is a clear overstatement.

However, all four battleships hit by torpedoes were out of the war six months or more, so it can also be said that those eleven aircrews fulfilled the Japanese hopes for the Pearl Harbor attack.

The shortfalls in the torpedo attack can be mostly attributed to the planners and their unrealistic prioritization scheme and awkward attack formation, and the lack of a realistic rehearsal. Near-collisions caused aborted attacks. An attack that should have taken less than 90 seconds stretched out over 11 minutes from first run to last.
²⁰
All the bombers that were going against the primary targets, the battleships, attacked after the defenders’ ready machine guns were firing.

The greatest indictment of the planners’ prioritization scheme is that not one torpedo bomber intentionally attacked anything other than what they thought was a battleship.

The Torpedo Attack: Plans v. Reality

The following two flow diagrams illustrate the difference between plans and reality in combat. It puts to question those who believe that “the attack was almost textbook perfect.”

(10) Timeline of Planned Torpedo Attacks on Carriers and Battleship Row

(11) Actual Development of Torpedo Attacks on Carriers and Battleship Row

The first chart shows what the Japanese planned. The time scale is shown across the top. The
Hiryu
and
Soryu
groups of eight torpedo bombers each were to attack the carrier anchorages at seven-second intervals. With two targets, the two formations could attack simultaneously, separated laterally. The attack should have been concluded, from first drop to last, in under a minute.

The
Akagi
and
Kaga
groups of 12 torpedo bombers each would simultaneously attack the other side of Ford Island, going after the ships at Battleship Row. There was adequate room for the two groups to attack together, separated laterally, even if they all chose to attack down the length of the Southeast Loch. Their attack should have been executed in under 90 seconds.

The second flow chart shows a reconstruction of the events of the torpedo attack based on post-war interviews with veterans and official reports. The blocks on the left show the formation groups and the pilots in their order of attack. An “x” indicates those shot down. The dotted lines show events that are interrelated (such as one pilot observing another group’s attack), which helps to establish the order of occurrence of the events.

The times of the events, shown in boxes following the “approximate” sign (“~”) provide an estimate of the time certain events were initiated, based on records and reports, and plotting out the time and distance of the tracks of the various groups. The initiation of the attack against the carrier anchorage is established by US witnesses, as well as the logged time when ships sounded the air raid alarm along Battleship Row.
²¹
The torpedo hit on
Helena
is marked by her engine room clock, which stopped at 0757. The attack against the carrier anchorage occurred before that. The beginning of the attack on Battleship Row is approximated by testimony that it was after Prep but before Colors, and the time and distance required by the groups to get in position. The end of the attack, at approximately 0810, is established by Stillwell’s assessment of when
Arizona
blew up,
²²
coupled with the testimony of sailors on the
Vestal
that a torpedo was seen heading in their direction seconds before
Arizona
detonated. This torpedo was likely launched by Petty Officer Second Class Kumamoto Kenichi against
Nevada
, and was the next-to-last torpedo dropped. Log entries from various ships place
Arizona’s
magazine explosion as early as 0806.
Vestal
, alongside
Arizona
, logged it at 0820.

The flow chart provides an altogether different impression of the attack. Rather than a smooth, “textbook” operation, there were significant problems with visual identification of targets, command and control, and mutual interference.

The groups targeting the carrier anchorages demonstrated the faulty principles upon which the attack was based. The idea of a prioritization scheme that the aviators were to follow based on ship identifications made “on the fly,” plus the authority given to individual aircraft to break off targets at their discretion, meant that the
Soryu
and
Hiryu
torpedo attack aircraft scattered, wasted most of their torpedoes on poor targets, and disrupted the
Kaga
and
Akagi
groups’ attack on Battleship Row. Of the 16 bombers assigned to the carrier anchorage, only five attacked battleships.
Utah
and
Helena
were both attacked under the supposition that they were operational battleships.

The differences in the flow charts show the gap between planning and reality. What could have been a smooth attack was marred by considerable confusion. The second chart is based on the testimony of the Japanese aviators who survived the war. It is likely, given the timing, that there were many more cases of mutual interference and aborted attacks than are recorded.

All of the B5N Kate losses were from
Kaga
’s air group, which attacked last—five of the last seven torpedo bombers were shot down, four before they could deliver their weapon. But for the premature warning caused by Fuchida’s failure to communicate the correct attack plan, the attackers might have gotten in and out without losses.

The black boxes in the chart show the immediate post-battle Japanese assessment of the attack.
Soryu
and
Hiryu
together reported 11 hits distributed over three battleships, and three hits on a heavy cruiser (14 hits out of 16 aircraft).
Akagi
reported 11 hits distributed over three battleships (11 hits out of 12) and
Kaga
eight hits on two battleships (eight hits out of 12). Thirty-three hits were claimed. Four aircraft were shot down before they could launch their torpedoes, and one torpedo was jettisoned due to a near-collision with another plane, leaving 35 torpedoes launched for a claimed 94% hits.

Overall Assessment of the Torpedo Bombers

The effort of the torpedo bombers must be seen from two viewpoints.

First, they accomplished Yamamoto’s objective to sink four battleships. Mission accomplished, well done; for such a daring attack there is no higher accolade.

Second, their efforts could have accomplished so much more. Eleven torpedoes accomplished their objective out of 40 brought to the battle. The rest were wasted in overkill, against improperly identified targets, or simply missed hitting a ship. A large degree of the blame can be attributed to the planners’ ideas of how the attack should be conducted. There were shortfalls in target distribution instructions, designated attack profiles, and command and control. Blame must also go to the strike commander for fouling up the ordered attack plan, which resulted in premature warning for the defenders.

The Japanese did not appear to use radio communications for tactical control, which effectively meant their commanders had no control after battle was joined. Fuchida himself was in a level bomber attacking from 3,000 meters altitude while the heavy-hitters, the torpedo bombers, upon whose shoulders the fate of the attack rested, went in at 20 meters. Fuchida could exert no control over the torpedo attack while he was busy dropping his bomb. He was in no position to exert control for the entire duration of the first wave’s attack. He transmitted the order, “Charge!” and command and control went by the board.

The torpedo bomber leaders had limited ability to control their own subordinates. Their aircraft were strung out in lines miles long, out of reach of anything other than the most basic “follow me” leadership. There is no evidence that any torpedo leader attempted to re-direct any portion of the attack against more appropriate targets other than by leading their own wingmen, that is, in those cases where the wingmen decided to follow.

Subordinates were given the authority to pick their own targets, a necessary principle when applying a prioritization scheme. However, this also allowed very junior airmen to make mistakes without a way for the more experienced leaders to exercise effective supervision. Aircraft missed turns, lost sight of their leaders, and had near-collisions and aborted runs as aircraft milled about looking for targets while trying to get in and out as rapidly as possible. Many of the torpedo bombers effectively made their attack decisions independent of their leadership.

The inflexibility of the planning and training efforts must also be faulted. The large number of B5N Kates allocated to high-altitude bombing with AP bombs was excessive once it was known that there were no torpedo nets protecting the battleships in the harbor. Trading in 20 AP bombs for 20 torpedoes would have been like trading three AP bomb hits for 12 torpedo hits. Granted, the torpedo hits would likely have been directed against cruisers and destroyers, but most would argue that sinking three or four cruisers and some destroyers in exchange for a small chance of crippling an additional battleship was a worthwhile trade.

The prioritization scheme for the attack was useless, and mostly ignored. Not one torpedo was intentionally launched at a cruiser.

Looking at the torpedo attack as a whole, the planners’ efforts merit no praise. The torpedo bomber aircrews, hampered by a poor approach plan and an unworkable prioritization scheme, had a lot to overcome. Poor delivery techniques and target selection limited the effective torpedoes to less than one third, an unimpressive result.

Lack of SEAD in the “No Surprise” Scenario

The volume of AA fire undoubtedly contributed to the below-expectations performance of the torpedo attack. The total of 19 confirmed torpedo hits
²³
was well under the 82.5% hits recorded in the last practice session (a projected score of 33 hits out of 40 torpedoes), and also under the planners’ earlier expectation of 27 hits. While fewer hits ought to be expected under combat conditions, the hit percentage compares unfavorably with the performance of the British at Taranto, where 9 of 12 torpedoes (75%) scored hits in a night attack under more trying conditions.
²⁴

The problem of American AA fire could have been mitigated by better strike planning. The only difference between the “surprise” and “no surprise” plans was in the order in which the strike aircraft would approach their targets. There were no changes in the assigned targets. In the “no surprise” plan, the assumption was that the bombers “would create so much confusion and draw such heavy fire upward that the torpedo bombers could sneak in virtually unseen, securing a high percentage of direct hits and suffering little damage in exchange.”
²⁵
But all of these dive-bombers were to attack airfields, not ships or AA positions. Guns on the ships that would be firing on the torpedo bombers could generally not bear in the direction of the dive-bombers attacking Ford Island, and were out of range of the ones attacking Hickam Field. The “no surprise” plan did not,
could not
, divert any fire away from the torpedo bombers.

Genda and Fuchida’s move to change the order of the attack if surprise was not achieved was less than useless—it instead provided warning so that the defenders could prepare to receive the torpedo bombers’ attack. There were no provisions to directly suppress or divert those AA batteries most likely to interfere with the torpedo bombers’ runs, that is, the harbor-side batteries of the battleships and the guns of the ships moored at the Navy Yard.

The first wave included 54 dive-bombers assigned to hit airfields. Some of these could have been reasonably employed in clearing the way for the torpedo bombers, particularly considering that in the “no surprise” situation, many of the defending fighters could already be airborne and past the ministrations of dive bombers. The first bombs, instead of hitting a hanger and reconnaissance aircraft at the south tip of Ford Island, ought to have been used to suppress AA fire. There were also 45 A6M Zeros in the first wave, all of which were assigned to attack airfields. Remarkably, the nine fighters—only nine!—accompanying the torpedo bombers departed ten miles short of the harbor to strafe the Marine Corps Air Station at Ewa. Considering the value and vulnerability of the torpedo bombers, these fighters ought to have escorted the torpedo bombers all the way to the target, and maintained top cover for the duration of their attack. Some of them could have provided SEAD support—a single strafing run against
Bagley
could have gone far towards saving several torpedo bombers, which might have resulted in another two or three hits. In other words, a single strafing run might have been worth half a battleship.

The idea that the torpedo bombers were to attack “at almost the same instant” applied only to the initiation of the attacks which, remarkably enough, they nearly achieved—torpedoes were in the water against targets at the west and east sides of Ford Island within minutes. However, there was enough time, between the following aircraft, that ships were able to sequentially engage them as they arrived (according to US witness reports) in clusters of three to five aircraft with pauses between clusters. Within each cluster witnesses reported the aircraft attacked with between six to twenty-five seconds separation between aircraft. The attack stretched out over at least eleven minutes and possibly longer, hardly a “simultaneous” attack.

Suppression of a target ship’s AA fire was a concept established in the 1930’s, and employed by the Japanese in their “massed attack” doctrine.
²⁶
The tactic consisted of fighters strafing the AA batteries of the target ships, or bombers delivering contact-fused bombs, just prior to or at the same time as the torpedo planes’ attack. The intent was to kill the gun crews or have them hiding under cover while the slow, vulnerable torpedo planes made their runs. Such measures could have been highly effective against the American battleships, which had many of their heavy AA guns (5”/25s and 3”/50s) in exposed mountings without splinter vprotection.
²⁷
This tactic was in the Japanese kit bag. It should have been employed.

Assessment: Level Bombers of the First Wave

Of the 50 800kg bombs assigned against inboard battleships, eight scored direct hits on battleships—six on inboard and two on an outboard ship.

The distribution of the 800kg bomb hits was effective. All inboard battleships were hit: two hits on
Tennessee
, two on
Maryland
, and two on
Arizona
, including the hit that caused the spectacular detonation of the ship’s forward magazine. Two bombs hit an outboard battleship,
West Virginia
. There were two additional “collateral damage” hits on the repair ship
Vestal
, moored outboard of
Arizona
.
Vestal
suffered severe flooding and had to be beached.

Fuchida claimed that he instructed the level bombers to concentrate on one battleship to ensure its destruction. This statement does not match with what happened in the attack. The table shows Fuchida’s possible briefed instructions to concentrate on a single battleship, the best possible distribution of attacks, the distribution actually achieved during the battle, and hits achieved.