Alan D. Zimm
Page 35
Genda categorically denied that any confrontation took place or that a proposal for an additional strike arose. He did not “take up the battle” for an additional strike, having realized long before that Nagumo had his mind set against such an attack. Genda believed bringing it up would be of no use.46 He stated in his memoirs that he was aware of the scene in Tora! Tora! Tora!, but explicitly denied that any such exchange took place or that a follow-on strike was proposed by Fuchida at all.47
Fuchida apparently noted American post-war statements regarding the supposed importance of a third strike against fuel and shipyard facilities and created fictional conversations that raised his perspicacity to heroic stature.48
The executive secretary of the US Naval Institute asked Genda why the Japanese did not bomb the fuel tanks. “He replied ingenuously that nobody had thought of this target.”49 When interviewed in 1945 immediately after the war, before all the American comments about striking the shipyard or the oil tanks were available in Japan, Fuchida was asked why there had been no third wave strike against Pearl Harbor. Fuchida made no mention of proposals to further attack the shipyard or the fuel tanks.50
Infrastructure targets had been briefly considered by the Japanese planners. Genda rejected them in his initial estimates because there wasn’t enough ordnance to spare (recall his dictum that hitting a few critical targets decisively was better than hitting many targets with only minor damage). There wasn’t sufficient ordnance to thoroughly attack fleet and OCA targets as it was, and a few odd bombs directed against the shipyard or the oil tank farms during the first or second waves would have been a wasteful half-measure—more like a hundreth-measure.
Thousands of miles away, members of the Combined Fleet staff, including the Chief of Staff Ugaki and Yamamoto, considered follow-on strikes. These officers appear to have been looking towards a more complete annihilation of the Pacific Fleet, and were not considering infrastructure targets.
Genda considered remaining in the Pearl Harbor area for days and dispatching repeated attacks but, as Willmott has noted:
… [Genda] was not necessarily thinking in terms of attacks on port facilities, shore installations and the like. He was thinking primarily in terms of inflicting crippling losses upon the US Pacific Fleet. Indeed, on the morning of the attack Genda limited himself to the proposal that returning Kates should be armed with torpedoes to meet any American forces which tried to mount a counter-attack, but that if none materialized, the Kates should be armed for the normal bombing role. Such deliberation amounted to no more than normal staff procedure, and there seems to be little evidence to suggest that Genda believed a follow-up attack would be necessary and on his own admission he made no representation to his superiors which suggested he was convinced of the need for such an operation.51
Some, particularly the more junior staff officers assigned to the Combined Fleet, were inflamed with fighting spirit, stoked by relief that great things had been accomplished at little cost, and were ready for a repeat performance; some felt that Kido Butai was still in dangerous waters, and the additional gains were not worth the additional risk.
One man staunchly against such an attack was Nagumo. He had doubts about the raid from the outset, and had shouldered for weeks the worry that his fragile carriers could be hit while thousands of miles from the nearest friendly port. When the attack met its objectives, he was more than happy to accept an unexpectedly one-sided victory and depart.
The idea that others would suddenly want to champion a return attack to hit shipyard and fuel facilities does not fit with the logistics-blind worldview of Japanese naval officers.
Realizing that the Japanese would likely not have gone after the shipyard and docks and fuel farms does not finalize the debate. Would a third wave attack against those targets been as destructive and as debilitating as so many maintain?
Composition of a Third-Wave Strike
Three hundred fifty aircraft were sent in the two waves of the attack. Of them, 29 (8%) were shot down and another 111 damaged,52 of which 10 to 15 (perhaps as many as 20) were damaged so severely they were jettisoned. Others were written off as unsalvageable. Of the other damaged aircraft, it is not known how many could not be flown until they were repaired by the ships’ maintenance force.53 Willmott reports that once all the aircraft had returned to the carriers the Japanese had 265 aircraft available for operations.54
The Japanese would not have launched another two-wave attack with all available bombers. They were concerned that the US carriers, so far unlocated, would appear and attack. A duplicate two-wave attack would not leave aircraft to search for or strike American carriers. They undoubtedly would have held ready a strike armed with counter-shipping munitions.
If another strike was to be launched, the first order of business would be to launch reconnaissance to ensure the American carriers would not interfere. They could be almost anywhere, to the northeast between Hawaii and San Francisco, east (San Diego), northwest (Midway), west (Johnston Island), or south (Palmyra and the southern training operational areas). Because the Japanese had made a high-speed night transit, they could not even be sure that carriers were not to the north. A 360-degree search out to 250nm would be prudent. If the Japanese used 10-degree search intervals with a single aircraft on each track, 35 aircraft would be required.
The aircraft for this search could come from several sources. First, there were two cruisers accompanying the force, Tone and Chikuma, specially designed to handle six reconnaissance floatplanes apiece. If they contributed ten aircraft, the balance of 25 would come out of the carriers’ complements. These would be B5N Kate carrier attack bombers on the carriers, which had the dual mission of reconnaissance as well as attack. There were the aircraft carried by the two fast battleships that accompanied the carriers, but these aircraft were usually employed in the inner anti-submarine patrol.
The Japanese carriers started with 144 B5N Kate carrier attack planes and 135 D3A Val dive-bombers. 16 Kates were lost or written off after the attack along with 31 Vals, leaving 128 Kates and 104 Vals. The crated spare aircraft would require at least 24 hours to assemble.
If one-third of the remaining aircraft were retained as an anti-shipping reserve, 70 B5N Kate carrier attack bombers (with two or three 250kg bombs each) and 70 D3A Val dive bombers (with one 250kg bomb each) could be employed in a third wave attack. They could deliver 210 to 280 250kg bombs.55
This is a high estimate. It is more likely that the Japanese would have retained at least half their aircraft as insurance against enemy carriers, and, as they viewed the B5N Kate as their real ship-killer, they would have retained a greater proportion of them for the anti-shipping strike. 100 of the modified “shallow water” torpedoes were delivered for this operation, and 40 expended in the attack. That might have limited the number of B5N Kates in the anti-shipping strike to 60. However, there may also have been unmodified torpedoes aboard.
Two hundred eighty 250kg bombs can be used as an upper estimate of the ordnance a third wave attack might deliver.
The Japanese Should have Attacked the Shipyard…
The first issue is to calculate how much destruction 280 250kg GP bombs could have inflicted on the shipyard.
Shipyard Facilities
Measurements taken from aerial photographs and confirmed by contemporary records give the total area of the naval shipyard and adjoining piers as 498 acres, or 21,692,880 square feet.56 According to the United States Strategic Bombing Survey, calibrated for the specific bomb scaled from a US 500-pound GP bomb, a Japanese 250kg GP bomb might destroy an area of approximately 4,400 square feet against industrial facilities.57
Four assumptions can be made, all favoring the attackers:
• none of the aircraft are shot down before dropping their bomb(s) (an unlikely assumption, considering that defenses would be alert, Army AA batteries would have received their supply of ammunition, the search radars were operational and the remaining fighters would be on alert);
; • all of the bombs hit inside the Navy Yard area (possible, if the best Japanese level bombing crews were assigned the attack);
• none of the bomb effects overlap (possible, if the aimpoints were suitably distributed and the bombing precise, but unlikely);
• the lethal area of the Japanese 250kg (551-pound) bomb can be scaled from the US 500-pound GP bomb (the Japanese bomb had a 0.2 second delay, which would mean it would tend to bury itself in the ground before detonating, making a deeper crater but damaging a lesser area than the US bomb. This assumption overestimates the lethality of the Japanese bomb); and
• no duds or low-order detonations (highly unlikely, considering the high dud rates experienced during the actual attack).
Under these assumptions the attack would destroy less than 6% of the area of the Navy Yard. Giving the assumptions a more realistic twist, damage could have been half that or less.58
The US Strategic Bombing Survey, when examining bomb damage on German factories, found that the destruction of a building did not imply destruction of the contents. Often there was only temporary, repairable damage to the machines inside, which were rapidly returned to production. In Hawaii’s mild climate all that might be required was a solid foundation and canvas to keep out the rain.
The possibility of fires is not included in the above calculation. Fires, unchecked, could greatly spread the extent of the damage. The firefighting capacity of the Navy Yard, naval base, and nearby Hickam Field was inadequate, even when augmented by cooperative support from the civilian fire fighting organizations at Honolulu. Hickam’s sole fire truck was destroyed in the strafing.
When the Japanese bombers struck the Philippines’ Naval Yard at Cavite a few days later, the shipyard was largely burned down. However, the Cavite Yard was smaller, crowded, and the buildings largely made out of wood, conditions not duplicated in the Pearl Harbor Yard. Even if fires doubled the area of the shipyard damage, damaging 12% of the navy yard would not place the yard out of commission.
Regenerative Capabilities
The Navy Yard would have considerable regeneration capacity, that is, the ability to repair itself. The submarine base had repair facilities. In addition, there were the civilian facilities at Honolulu—the shipyard there serviced very extensive traffic through the port, on the order of a ship a day. The facilities in place to service that volume of traffic could have helped set damage to the Pearl Harbor Naval Shipyard to rights. There were other civilian companies that could help, and did provide extensive salvage assistance after the attack. Among many others, the Pacific Bridge Company provided divers and underwater concrete for covering torpedo holes in the battleships, and the General Electric Company assisted with restoring salt water-damaged electric motors, particularly the installations in the electric drive battleships.59
There was also the very considerable afloat repair capacity:
3 Repair Ships (Medusa, Vestal, and Rigel),
2 Destroyer Tenders (Dobbin, Whitney),
2 Seaplane Tenders (Curtis, Tangier).
There were also two small seaplane tenders, two converted destroyer seaplane tenders, and the submarine tender Pelias. There were another 12 large capable tenders elsewhere in the Pacific that could have been dispatched to Pearl Harbor.
Of all the tenders at Pearl Harbor on December 7th, the most capable were the three repair ships, two seaplane tenders, two destroyer tenders and the submarine tender. These ships had significant industrial capabilities, were stocked with machine tools and a foundry, and could do anything that a shipyard could do short of drydocking. The repair ships could “do practically anything except build [a battleship] from scratch”:60 rewind motors, cast and machine parts, shape and cut metal, build and repair valves, replace piping and electrical components, and much more. They were very capable of repairing the repair facility.
Skilled manpower was available, with hundreds of machinists’ mates and boiler tenders and ship’s carpenters released from the damaged battleships. This was a time when most every teenage American boy fixed up his own jalopy or helped repair his family’s farm equipment. People were used to making their own repairs, improvising fixes, making do with less. It was an adaptive, adaptable generation.
An example of what resolute American sailors and civilian contractors could accomplish was that of a small group in the Red Sea in 1942.61 Commander Edward Ellsberg arrived at the port of Massawa, recently abandoned by the Italians, with a small contingent of sailors and six civilian supervisors. He was tasked with restoring the naval shipyard’s capability, to make it available to service Allied ships damaged in the intense naval battles in the Mediterranean. The working conditions were horrendous: food was scant and poor, temperatures topped 110 degrees each day at 100% humidity, and the coolest bath and drinking water available steamed when released from the faucet.
To add to the challenge, the Italians had thoroughly destroyed the repair facilities. Every machine tool, power source, or mechanism of any kind had been smashed. Even hand tools did not escape destruction. There remained only a few hand saws, a few screwdrivers, nothing more. This systematic destruction was far worse than what would have resulted if bombs had destroyed a small fraction of the Pearl Harbor facilities.
But, as Commander Ellsberg related:
I had observed that while there wasn’t an unsmashed electric driving motor on any machine, the smashing had not been symmetrically done. On some motors, they had smashed one end, on others the opposite end, on still others the main frame. There were hundreds of motors involved of different sizes, but of each size there were dozens at least. That situation was the key to our solution. If only we could disassemble all the broken motors, out of some dozens of broken motors of a given size, I was sure we could find enough undamaged parts of every kind needed to reassemble a few complete motors at least.
Out of the disparate parts they were able to assemble a lathe and a milling machine. They used them to rebuild other machines. Discarded crucibles were used to cast gears. Quickly a fundamental capability was established, which was used to repair more capability, until “… in only one month after my arrival (we) had every sabotaged Italian shop in the naval base working at least the full capacity intended by the Italians themselves; in some cases more.”62
This feat was accomplished by only a score of Americans with some recruited Italian prisoners of war. This ingenuity would be demonstrated by Americans repeatedly throughout the war under near-impossible conditions.
Compared to the resources Ellsberg had available at Massawa, a Pearl Harbor repair team would have had untouched civilian repair facilities at Honolulu and the Navy’s tenders afloat, considerably more manpower, and the support of local civilian contractors, all in a congenial climate. In addition, for special or esoteric needs, the mainland was a week’s transit away by steamer, a day by air. Obtaining replacement machines or materials would have been a matter of prioritizing, and with the mood in the Navy in the weeks after the Pearl Harbor attack, prioritization would not have been an obstacle. Obtaining replacement parts and tools for Pearl Harbor would likely have been viewed as a sacred duty.
There is no reason to expect that the Navy Yard could not have restored itself to full capacity faster than was accomplished at Massawa.
Destroying the Power Plant
Morison criticized that the Japanese “did not even attempt to hit the power plant.” This was another comment made without considering the means to effect the destruction or the consequences. Morison evidently made the statement without knowing what constituted the power generation capability at Pearl Harbor. There was not just one power plant, but several in different locations, along with a new 20,000 kW bombproof plant that had been under construction since October of 1941. It was not just a case of allocating one spare Japanese bomb and the lights would go out and everyone would go home.
If the Japanese wanted to take out the power plants they could have obtained the necessary intelligence, and could have been able to identify
and target the plants from the air. However, their 250kg bombs were light for that kind of application. The USSBS found that knocking out generator halls was extremely difficult, and the damage often could be put to rights quickly.
The key to determining if the bombs were well employed would be the duration of the outage. It is likely that power would have been out for only a few days, perhaps hours. Historians never mention what would happen after the generators had been destroyed.
Every ship afloat had the capability to generate electric power for itself, often with sufficient overcapacity to allow for battle damage or to allow systems to be shut down for maintenance. This huge generation capacity could have been used to power the base.
In 1929 Tacoma, Washington was hit by a drought that cut the water supply to the city’s hydroelectric power plant. The carrier Lexington was directed to proceed to Tacoma to serve as a floating electric power station. Lexington arrived on 15 December, and two days later was tied into the grid and providing power at a cost of one cent per kilowatt-hour for 12 hours a day for the next 30 days. Lexington had a new turbo-electric drive using electricity to power her main propulsion motors, and had the capacity to generate 140,800 kW, so she was particularly suited to this task.63
Similarly, during the Korean War a destroyer escort provided power to Korean coastal towns cut off from their regular power sources.64
The battleship Maryland at Pearl Harbor had a turbo-electric main propulsion drive system similar to Lexington’s. Maryland’s plant was smaller, but the electrical demand from the naval base and shipyard would have been much smaller than that asked by the city of Tacoma, and there would be other ships available to augment the supply. Maryland had been hit by two AP bombs, but damage was minor, and her engineering plant was unaffected. She was moored inboard of the Oklahoma and pinned in her berth when that ship capsized, but freed on 10 December. She would have been ideal to provide this service. Alternatively, the tenders could have been used, as these ships were provided with sufficient electrical generation capability to power a nest of destroyers or submarines.