Alan D. Zimm

by Attack on Pearl Harbor: Strategy, Combat, Myths, Deceptions

  Regardless of warnings, six of the torpedo bombers attacked Utah, four of them after breaking away from their shotai leader. One torpedo missed so badly it hit Raleigh. Raleigh nearly capsized, forestalled by prompt damage control.12

  This waste of torpedoes can fundamentally be blamed on the planners. Word had been received that there were no carriers in Pearl Harbor. They let stand the attack on the carrier moorings hoping a carrier might return, a hope that ended up wasting six torpedoes.

  Their hope did come close to being fulfilled; Enterprise would have arrived on Saturday but was held up by bad weather. But a bad decision should not be considered good just because fortune intervenes. The fact remains that the planners left no provision to change the plan to react to updated intelligence.

  Toland stated that Utah was misidentified as a carrier, an assertion that has been echoed by other historians.13 Comparing the silhouettes of Utah with Enterprise (or any other carrier) makes this hard to accept. Photographs of Utah capsizing show that her decks “stripped and covered with planks” did not make for a carrier silhouette. Japanese veterans stated that Utah was actually misidentified as an operational battleship.

  The first physical errors are apparent. Of six torpedoes launched against Utah, only two hit their target. One hit Raleigh in the adjacent berth. One torpedo slid up a muddy beach onto Ford Island. The other two are buried in the harbor bottom. These bombers were unopposed by AA fire and had an easy approach path to their targets, virtually training conditions. They should have achieved the training level of success, five hits instead of two.

  In the absence of carriers, Soryu’s and Hiryu’s torpedo bombers were to search out and strike alternate targets. Matsumura related:

  My assignment was to find and attack a carrier in the harbor, so I tried very hard to locate one. But I could not find a carrier, so I hit a battleship…. I saw smoke coming from Ford Island but didn’t go into it. Instead, I took a detour and flew in the airspace off Hickam Field, but I didn’t plan to do this. During my initial attempt to drop my torpedo, I was too close to another aircraft. Because of this, my Type 97 [Kate] was rocked by this plane’s ‘prop wash,’ so I had to turn around and come back again…. [M]y torpedo hit the West Virginia.

  Another five aircraft attacked the 1010 Dock mooring occupied by an antiquated minelayer outboard of a modern light cruiser, a puzzling silhouette when backlit by the rising sun. The light cruiser Helena was a legitimate target on the priority list; however, it was not so important a target as to justify five torpedoes. The attackers saw in the confused silhouette what they wanted to see, a battleship, a common occurrence under the stress of combat.

  One torpedo passed under minelayer Oglala to explode against Helena. The blast split the seams of the WWI-era minelayer, which slowly filled with water and eventually capsized. Oglala was eventually salvaged, but with difficulty—she was raised and sank three times before she could be towed into drydock. This was done not because she was a valuable ship, but because her sunken hull blocked one of the most valuable berths in the harbor.

  Three of the torpedoes hit bottom. A photograph shows what might be the froth from the engines of two torpedoes stuck in the mud near the channel dredge, along the attack path leading to Helena.14

  The remainder of Soryu’s and Hiryu’s torpedo bombers attacked battleships; most went for Oklahoma or West Virginia, the recipients of more than their fair share of torpedoes.

  The reason why Oklahoma and West Virginia were disproportionately targeted is apparent from the chart. The approach to these ships was the easiest, a straight 1,000-yard run, flying along the Southeast Loch past the Navy Yard waterfront. In contrast, the approaches to Nevada and Arizona, shown on Fuchida’s chart, involved skimming over the Kuahua Supply Base. After clearing the turbulence generated off the fuel tanks, and the alternating sink and lift generated by alternating bands of land and water followed by another band of turbulence from the supply base buildings, the pilot would have about 6 seconds to throttle back, descend, establish launch parameters in speed, altitude, and attitude, and release their torpedo. These routes were impossible, and all the pilots had the good sense to avoid them.

  The alternative was to take the same route down the Southeast Loch on a course of about 300 degrees, and then, when near the junction with the main channel, rack the aircraft into an 80-degree right turn and release the torpedo on a course of about 020 degrees. That turn, at slow speed in a heavily loaded aircraft at an altitude of less than 60 feet, would be dangerous. The aim would have to be precise, as the targets would be foreshortened by the angle on the bow.

  This approach was selected by probably only one or two aircraft: Lessons praises those aircraft that, “realizing just prior to charging [firing] torpedoes that they were aiming at the wrong target, made bold turnings to the right targets amid fierce gunfire.”15 It is no wonder that Nevada was hit by only one torpedo, and Arizona none.

  The attack approach against California would be easier, but from the drop point the target angle against the ship was about 45 degrees off the port quarter, presenting a foreshortened target. One torpedo bomber, in a spectacular display of airmanship, approached from the south along the main channel, cleared the Navy Yard, angled to the left to line up the attack and dropped off the ship’s bow, scoring a hit.

  Attack Routes and Deconfliction

  An orderly attack was not achieved. The deconfliction plan, to have all aircraft make a left turn after dropping, was not always executed. Routes were blocked by AA fire and smoke. Formations became intermixed, runs were aborted, re-run, aborted again.

  In postwar interviews the aviators did not mention target prioritization; rather, they spoke of unexpectedly heavy AA fire, the difficulty of identifying targets, and their desire to get their torpedo into a battleship, any battleship. Only the most experienced and steady aviators thought of spreading the attack. What the planners saw as a simple task just could not happen under combat conditions. The fact that an attack planned to take two minutes actually took 11 to 15 is an indication of the severity of the problem.

  Overkill

  Fuchida’s 27 December 1941 map used to brief Emperor Hirohito shows 36 torpedo hits. Twenty-one were on Oklahoma and West Virginia, twice as many as needed. Five were on Helena, over 100% overkill, and six on Utah, all a waste. Thus, from Fuchida’s own report, 19 of 36 torpedoes (53%) were either overkill or wasted. Fuchida’s expressed desire to concentrate and bag at least one battleship may have been reflected in the concentration of fire, if only subconsciously.

  Another consideration comes from the viewpoint of the torpedo bomber pilots. Attacking at 20- to 30-second intervals, aircraft might only see a few previous torpedo plumes, if they registered any at all due to target fixation and tunnel vision. They would not have information regarding the total number of hits a given battleship had absorbed prior to their attack. The photographs attest that after a plume subsided, there were few clues to guide the later torpedo bomber pilots to facilitate a weapons distribution decision. An aircraft, seeing plumes on Oklahoma, would shift to the next easiest target, West Virginia. After a few hits on West Virginia, the plumes on Oklahoma would have subsided, inviting additional torpedoes to be directed at Oklahoma. The 70-second gap between the Akagi and Kaga attackers made the problem harder.

  To properly distribute their torpedoes under a prioritization scheme, the aircrews needed more information beyond that which they could collect with their own eyes. Otherwise, the harrowing approach would invite repeated hits on the easiest target. This occurred in the rehearsals and was not corrected.

  Lessons acknowledged “there were over concentrations of attacks and also some gaps which had not been damaged.” They attributed this to a number of reasons, including “errors in identifying ships in the aircraft reconnaissance report,” a somewhat odd notion, and perhaps a typically oblique Japanese reference to the torpedoes wasted against Utah. Lessons also blamed poor visibility caused by the smoke from burning ai
rcraft on Ford Island. This could be attributed to Fuchida’s error with the flare guns if it were true; however, the wind blew the smoke from Ford Island to the southwest, away from all the torpedo attack routes, so it is hard to see how smoke would have interfered with the attacks on Battleship Row. Photographs show Battleship Row clear of smoke until Arizona exploded, which occurred after the torpedo attacks had been delivered.

  Lessons also mentions that pilots could not evaluate the damage done by preceding torpedoes before launching theirs, and a concern that aircraft might run into the water columns from exploding torpedoes.

  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.