Attack on Pearl Harbor (42 page)
Read Attack on Pearl Harbor Online
Authors: Alan D. Zimm
In the end, the attack time was postponed from dawn to 0800 because a dawn attack would require launching in the dark, and
Zuikaku
and
Shokaku
’s air groups were not qualified for night operations. X Day was delayed from 20 November to 7 December because the skill level of the aviators was judged to be insufficient, and more training was needed.
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Ironically, this served to their advantage: if the attack had gone down on 20 November the Americans would have been in Alert 2, with dawn patrols aloft, AA batteries in place, and the Japanese would have suffered.
2) “
Thank goodness the fleet was in port…”
Attacking the Fleet Outside the Harbor
Some commentators believed it was fortunate that the US Pacific Fleet was in port, because if it had been attacked at sea, the defeat would have been much more serious. Ships sunk in deep water would have been unsalvageable.
In a scenario supporting this theme, Japan does not attack Pearl Harbor; instead the Pacific Fleet sallies forth to the immediate relief of the Philippines. It is destroyed in deep water by Japanese long-range torpedo bombers operating off island bases. Not only are the battleships all lost in deep water but so are their crews, decimating the experienced Regular Navy talent foundation that served as the cadre for a mass of new construction ships and delivered training to the masses of wartime volunteers and draftees.
While this discussion will explicitly analyze the first scenario, the second can be considered as a lesser and included case.
The “Fleet at sea off Pearl” scenario was tested in a wargame conducted under the auspices of a television program, featuring some of the luminaries of the wargaming world and with the combat results adjudicated by a “sophisticated computer program.”
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In the scenario the US fleet received warning of the attack at 0530, allowing sufficient time for the US commander to sortie the majority of the fleet and meet the air attack while underway in deep water, with the ability to maneuver at full speed, GQ and Zed set, and all AA batteries ready. The results were dramatically announced: four American battleships sunk in exchange for 75 Japanese aircraft shot down.
One of the participants in the game, a retired Rear Admiral, stated that he did not believe these results. He felt that the Americans suffered far too many losses in the game. A careful assessment would suggest that he is correct.
To sink four battleships at sea would have required a minimum of sixteen hits, or 40% of the available torpedoes, very close to the 48% hits the Japanese achieved against stationary targets in a surprise attack. At sea, ships would have been able to maneuver freely, and torpedo hits would have been harder to achieve. Over the last months the US Fleet had been training hard and sailing as if under wartime conditions, and their training and readiness was considered to be excellent. Material Condition Zed would have been set, so the progressive flooding that was so damaging to ships moored in Pearl Harbor under holiday routine would not have occurred as readily.
Compare this situation with that of the attack on the
Prince of Wales
and
Repulse
. There, 51 torpedo bombers took off on the mission and 49 torpedoes were launched achieving 6 to 8 hits, or a hit percentage of 12 to 16%.
In that engagement, the two battleships were escorted by destroyers with no area air defense capability. Most of the AA capability was vested in the
Prince of Wales
. A single devastating torpedo hit, the first to hit the ship, disabled most of the
Prince of Wales’
AA capability. A torpedo exploded on the port side aft; it dislocated a port shaft, which thrashed about in the shaft alley smashing the surrounding bulkheads and destroying the watertight integrity of compartments all the way from aft to amidships. Several major engineering spaces flooded, some so fast that the crews could not shut watertight hatches behind them as they evacuated, causing the flooding to spread further. There was a loss of electrical power aft, and the ship took on an immediate 11 degree list, enough so that the 5.25-in AA guns on the high side could not depress sufficiently to engage torpedo bombers. Not one of the eight 5.25-inch gun turrets could be trained due to a loss of electrical power. The six mounts of 8-barrel 2-pounder pom-poms had problems with their ammunition, causing the guns to jam. Stoppages were frequent; one of
Prince of Wales’
pom-poms suffered 12 failures, another eight. With power lost all the pom-poms aft were frozen. Sailors tried to train them manually, without success, and in one case they even tried rigging a chain pulley for additional leverage.
With
Prince of Wales’
AA weapons largely out of action,
Repulse
had little to contribute to the defense. She was a WWI vintage ship with only eight hand-operated 4-inch AA and two pom-pom mounts.
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And yet, against this anemic AA opposition, the Japanese achieved only 12–16% hits.
A torpedo hit percentage of 15% underway (the historical average during the war in the Pacific) against the fleet off Pearl Harbor would have given six hits out of the 40 torpedo-armed B5N Kate carrier attack bombers. Battleships at sea could be expected to sustain at least four aerial torpedo hits without sinking. So, six hits might have (if concentrated) sunk one battleship; if distributed over several ships, all ought to survive.
Similarly, the hit percentage by 800kg bombs would be reduced from that achieved against the stationary ships on Battleship Row. Hits by level bombers against maneuvering targets were notoriously hard to achieve during all of WWII. A 10% hit rate (5 hits) would have been exceptional, higher than the hit percentage exhibited over the entire war, which was probably less than 1%.
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Five hits (with a 60% dud or reduced yield rate) would not have done serious damage to the battleline as a whole.
American AA was considerably advanced over the British. The 40 torpedo bombers would have received considerably more attention than that offered by the British battleship and battlecruiser. An apt comparison would be the battle of 12 November 1942, where 21 Japanese twin-engine torpedo bombers attacked six American transports off Guadalcanal protected by three heavy cruisers, two light cruisers and eleven destroyers, about half the AA potential as the seven battleships, three light cruisers, and nineteen destroyers that might have been steaming off Pearl Harbor on 7 December 1941. A view of that action was related by a gunnery officer on the destroyer
Sterrett:
Now I gave the gun captains the signal they had been waiting for—“Commence firing! Director control. Rapid, continuous fire.” The crews loaded the shells and powder cartridges into the guns, and in four seconds the first salvo was on its way. The concussion was terrific, but by now we were used to it. Our first bursts were low and short, so we changed our trajectories. We were the ship closest to the attackers, and our tracers were headed straight at the lead plane. On our third salvo we made our first kill. With a tremendous explosion and a huge cloud of smoke our target fell out of the sky, its tail section completely demolished. The plane hit the water with a crash, skidded, tumbled, came to a stop, and burned like all the fires of hell. We shifted our sights to the next plane in line and immediately hit it squarely. It simply disintegrated in the air—big chunks of airplane splashed into the sea across a wide area.
Now every ship opened fire at one target or another. Because we were between the main body of the formation and the attackers, hundreds of shells streaked over our heads and hit the water ahead of the planes. The sky was filled with antiaircraft bursts… The Japanese formation broke up and start[ed] dropping torpedoes all over the place. Some fell at such a high speed that they somersaulted, while others ran true but wide. Two passed close astern of us. Two planes that we had hit fell into the water after they had flown directly over us. Our 40- and 20-mm shells made contact with engine nacelles and fuselages. Our automatic weapons gunners were terrific: Kelly, James, Keenum, and Grimm had nursed those guns, firing short bursts every day, and had sometimes slept by them, just waiting for a chance like this. The steady stream of tracers pouring out of those gun barrels was a beautiful sight…. twenty of the twenty-one bombers were in the water, most of them on fire and all of them destroyed. Not a single torpedo had reached its target. The wreckage of downed aircraft covered the water in every direction.”
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This event was 11 months into the Pacific war, after the air threat had been recognized and many warships’ anti-aircraft armament had been augmented from pre-war standards. For instance, the armament on the destroyer
Fletcher
, on the ways on 7 December 1941, consisting originally of one four-barrel 1.1-inch mount and six single 20mm mounts. By the end of the war she had five two-barrel 40mm mounts and seven single 20mm guns.
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What the battle fleet would have had in 1941 off Hawaii was much greater than what the smaller number of ships had off Guadalcanal on 12 November 1942. They both would have had the same fundamental AA fire control directors that proved so successful throughout the war. There is no reason to believe that the attacking Japanese aircraft would have been any more successful off Oahu than they were off Guadalcanal.
The likely Japanese losses can be calculated as they were in
Chapter 9
, assuming:
| • | the heavy AA was engaged for 15 minutes at an average rate of fire of 8 rounds per minute; |
| • | the machine guns engaged for 8 minutes at their practical cyclical rate; |
| • | the fleet consisted of eight battleships, four cruisers, and 20 destroyers with AA-capable main batteries. |
Using the 1942 RPB numbers, 158 out of the 186 attackers in the first wave would be shot down, for 85% losses. This does not include losses inflicted by US fighter CAP from Oahu, or that the attackers could have been intercepted on the way to the fleet and on their return by AAC fighters.
In other words, an attack on the fleet underway off Pearl Harbor would have had results more like those seen in the Japanese torpedo plane attack off Guadalcanal than what was seen inside Pearl Harbor on 7 December 1941.
This calculation was based on RPB figures taken from combat experience. The defensive fires would be formidable, the Japanese losses would have been crippling, and the fleet would not have suffered damage anything near the scale that was sustained in the actual attack in the harbor.
The Fleet Is Attacked at Lahaina Roads
Another possibility was that the fleet would be anchored at Lahaina Roads, off Maui, 80 miles southwest of Oahu. The Japanese intelligence officer was sending daily position reports on the location of the fleet. With that in mind, this scenario breaks into two situations.
The first is where the incoming strike was diverted to Lahaina Anchorage after being launched. This case is nearly like that of the “fleet at sea” scenario. An anchor watch would be maintained on each of the ships, with personnel on the bridge and on the foc’sl to watch for the anchor dragging. The steam plant would be hot, with boilers on the line and steam to the nozzle blocks of the main engines. To get underway, it would be a simple procedure to slip the anchor chain, take the main engines off the jacking gear, and open the throttles. Top speed would not be available, but the ship would be able to maneuver.
Some of the ships would not be fast off the mark and might still be at anchor when the attack developed. A higher percentage of hits by the torpedo planes could be expected; however, in the usual fleet anchorage deployment, the torpedo planes would also have to fly close by cruisers and destroyers anchored on the periphery of the anchorage. It could be expected that many more of the torpedo planes would be hit before they could launch their torpedoes. The battle could take on the aspect of the torpedo bombers’ attack off Guadalcanal. Six to ten torpedo hits might be a reasonable estimate.
The second case is where the Japanese knew that the force was at Lahaina Anchorage a day before the strike. The plan was for the attack to be executed, with a significant difference. The 50 Kate torpedo bombers that were allocated as high-altitude level bombers would now be armed with torpedoes. These crews had not practiced with torpedoes—many had never even dropped one in training. So, gauging the number of hits this group would achieve is problematic. These crews might be considered at the same training level as the crews assigned to launch torpedoes at the beginning of their training. In the first torpedo-launching exercises, the results were described as “very poor,” with hits on the order of 15%.
The targets ships might be underway and maneuvering. The torpedo bombers would be faced with considerable defensive fire. The anchorage waters are shallow (in some places, single digit fathoms), so some torpedoes would strike the bottom. Applying a generous hit percentage of 15% would result in an additional 7 or 8 hits, for a total of 14 torpedo hits. If these hits were distributed over the battleships there would be two hits per battleship (if evenly allocated), or perhaps two or three battleships sunk (if the torpedo hits were concentrated on only a few ships).
This scenario results in about the same number of hits on the battleships as was achieved against the fleet in Pearl Harbor, but not the same losses, since the ships would have Zed set and be active in their damage control. The loss calculations were based on the Japanese estimate that it would take four torpedo hits to sink a battleship, not the US estimate of six to seven when underway in material condition Zed. An additional consideration is that there are good places to beach a sinking battleship within a few hundred yards of the anchorage. So, an attack against the fleet at Lahaina Roads would likely cause less damage then one against the fleet in harbor.