Dec 7

December 7, 1941: The Destruction of the Battle Line at Pearl Harbor

Friday, December 7, 2012 1:00 AM

This article was written by Thomas C. Hone for the December 1977 issue of Proceedings magazine.

When aircraft of the Imperial Japanese Navy attacked elements of the U.S. Pacific Fleet in Pearl Harbor on 7 December 1941, their primary targets were the seven battleships berthed alongside the large mooring quays which ran parallel to the southeast side of Ford Island. The Japanese aircraft attacked the stationary battleships with aerial torpedoes, 40-centimeter (15 1/2-inch) armor-piercing shells converted to bombs, and 250-kilogram (550­pound) high-explosive bombs. The battleships Oklahoma (BB-37, launched 1914) and West Virginia (BB­48, launched 1921) sank during the attack, and the Arizona (BB-39, launched 1915) was destroyed when an armor-piercing bomb set off an explosion in her forward main magazines. The Nevada (BB-3 6, launched 1914) and California (BB-44, launched 1919), both of which sustained serious underwater damage during the Japanese raid , gradually filled with water and sank, the latter staying afloat until 11 December. The Tennessee (BB-43, launched 1919) and Maryland (BB-46, launched 1920), moored inboard of the West Virginia and Oklahoma respectively and thus sheltered from the torpedo attack, suffered minor damage from armor-piercing bombs. The fleet flagship Pennsylvania (BB-38, launched 1915), which was in drydock number 1, sustained only superficial injuries.

Of the five battleships which the attacking aircraft could reach with bombs and torpedoes, all were sunk. The available documentary evidence suggests that, of those five, the Oklahoma and Nevada were lost because of design defects , the West Virginia was simply overwhelmed by force her defenses were not meant to thwart, and the California was sunk because of the performance of her officers and crew. The Arizona‘s destruction is difficult to explain conclusively because the detonation of the ship’s forward magazines so thoroughly wrecked the vessel that no attempt was made to raise her. As a result, no detailed examination of the Arizona‘s hull was ever undertaken, and the physical evidence needed to demonstrate conclusively any weakness (or lack of it) in her armored decks has never been gathered.

The five battleships attacked by torpedoes in the first stage of the assault had two different forms of underwater defense. The first, worked into the Oklahoma, Nevada, and Arizona during modernizations between 1928 and 1931, consisted of an external bulge or blister and internal compartments backed by a longitudinal torpedo bulkhead of 40-pound nickel steel armor and 20-pound medium steel plates for a combined thickness of 1 1/2 inches. The bulge, or outer defensive layer, was empty. Behind the original shell of the ship was a layer of fuel tanks, and behind that layer was yet another, then the inner, armored bulkhead which stretched vertically from the double bottom to the third deck. The maximum thickness of the protective layer was 14 feet, and the two void layers inboard of the bulge were filled with fuel oil to absorb the blast and pressure of an exploding torpedo.

The second system, originally built into the Tennessee and Maryland classes, covered the center two­-thirds of each ship with a layer of five compartments with a total protective depth of 17 1/2 feet on each side. Immediately behind the shell was a void space 4 feet wide, while the next three compartments–­each 3 feet wide–were wing fuel tanks. The bulkheads of these compartments were designed to be stiff enough to resist compression but resilient enough to bend under the pressure of an underwater explosion. Behind the liquid-filled layers was a void 4 1/2 feet wide; its inner boundary was an unpierced longitudinal bulkhead of special treatment (armor) steel with a maximum thickness of 1 inch. The empty and oil-filled protective compartments were strengthened and subdivided by transverse bulkheads, and the spaces behind the torpedo defense system could be rendered watertight in the event of an attack. Both systems of defense used voids and liquid layers together, but the system designed originally for the Maryland and Tennessee classes was superior because of its greater depth and because it held sudden flooding to a minimum after an explosion.

The evidence suggests that the torpedo defense systems of the Nevada and Pennsylvania classes, even as modernized, were inadequate. On the other hand, the system designed for the Tennessee and Maryland classes–which were not modernized in the 1930s–was far superior; it kept the West Virginia from capsizing and should have kept the California afloat. The Nevada‘s underwater damage resulted from one torpedo and two bomb hits. While still in her berth, the ship was torpedoed

…on the port side between the two forward turrets at about frame 41, approximately 14 feet above the keel . . . . The innermost torpedo bulkhead was opened at seams and butts and compartments below the first platform deck between frames 30 and 43 (on the port side only) began to flood. [See Figure 1]

The Nevada slowly took on a 5° list to port, but counterflooding reduced the list to nearly zero . Opposed to the torpedo was a protective system composed of an external blister and two internal layers of fuel tanks backed by a 40-pound, 1-inch-thick armor steel torpedo bulkhead. The depth of this system was approximately 14 feet. The torpedo blew a large hole (16 feet long and 27 feet high) in the blister, and the explosion also ripped open the shell and inner bottom plating. The longitudinal torpedo bulkhead held, but it was dished in from frames 37 to 43 (24 feet) and from the “inner bottom to just above the first platform deck” (18 feet). There was some internal flooding just above, behind, and to either side of the damaged area, but it did not threaten the stability of the ship. As the Bureau of Ships damage analysis pointed out, “Considering the relatively low standard of torpedo protection in this area the structural damage inboard of the holding bulkhead was gratifyingly small. “

More serious underwater damage was caused by two of the three 250-kilogram bombs which penetrated the forecastle deck. Two of the three bombs sliced through the upper deck at frame 15; one broke through all the comparatively light decking in that part of the ship and exploded at frame 7, between the shell plating and a full gasoline tank. The damage caused by this bomb, a relatively small hole blown in the shell plating, was slight because the force of its explosive charge was absorbed by two liquid-backed boundaries (i .e., the shell plating on the bottom and the skin of the large gasoline tank). The other bomb, however, passed out through the starboard side of the ship at the level of the second deck and exploded in the water alongside, roughly between the first and second platforms. The force of this explosion caused the riveted joints along two sides of a line of plating below the waterline to give way, opening a large, right-angled gash in the ship’s hull. The inner bottom was also forced in, and several compartments on the first and second platforms were immediately flooded. The third bomb exploded after ricocheting off of the second deck at about frame 28. This bomb did not rupture the underwater body of the ship, but it did start a severe fire forward of number 1 turret. The fire burned for two days and severely hampered attempts to halt the progressive flooding which finally left the Nevada full of water and oil.

The Nevada faced a serious, but not insurmountable, problem: flooding forward of the main torpedo defense system. It could not be dealt with directly because the fire in the forecastle kept damage control parties away from that part of the ship. The ship did not remain afloat because the armored citadel could not be kept watertight. Water seeping through the bomb holes in the forecastle was not held there; instead, it gradually worked its way aft, especially through the ship’s ventilation system. The combined bomb and torpedo damage, and the counterflooding which was done to keep the ship stable, lowered the Nevada‘s bow until water entered the ship at the second deck level. Flooding of the main magazines simply worsened this situation, and ”… the lack of any watertight subdivision between the second and main decks from frame 30 to frame 115 . .. allowed water to enter ventilation intakes…” that led directly to the pump, dynamo, and boiler rooms. In consequence, initial flooding not of dangerous proportions slowly spread to such an extent as to cause the loss of the ship. (See Figure 2)

The California succumbed to two torpedoes and minor damage from one near-miss bomb. The two torpedoes struck the ship’s port side below the armor belt at frame 52 (between number 2 turret and the bridge) and at frame 101 (at number 3 turret) almost immediately after an attack alarm was sounded and before the maximum degree of watertight integrity could be set. (See Figure 3) The bomb exploded in the water alongside the port bow soon after; the force of the explosion forced in the plating between frames 10 and 15 (see Figure 4) and, “All compartments forward of bulkhead 21 on the first platform and three below on the second platform were flooded immediately. These, plus a few others which flooded more slowly put the California down by the head by about 3 1/2 feet.” This loss of trim, however, had no serious consequences for the stability of the California. The torpedo damage was a greater threat.

The torpedo which struck forward was opposed by the standard protective layer, 17 1/2 feet deep. The explosion of the torpedo warhead opened a hole 24 feet long by 10 feet high and broke or seriously deformed the antitorpedo bulkheads and their transverse stiffeners between frames 47 and 60. The shell and the outer bulkhead were blown open; the second bulkhead was deformed and holed by several large fragments; the third and fourth bulkheads were pushed in but not broken, and the fifth “…was undamaged except for a slight deflection of about 1 inch.” The torpedo which hit the ship aft struck an almost identical defensive system and

Damage resulting from this torpedo was almost a duplicate of that caused by the forward torpedo. The shell and number 1 bulkhead were blown open. Number 2 bulkhead deflected severely and had two fragment holes. Numbers 3 and 4 bulkheads deflected but did not rupture. Number 5 bulkhead was undamaged although . . . number 5 bulkhead had an 8-inch bulkhead fitting on the fuel oil filling line puncture the bulkhead just below the first platform level at frame 102.

The Nevada and California both had liquid-loaded torpedo defense systems, but the ability of the system built into the latter to absorb more damage is dear from the investigations conducted by the Bureau of Ships. The torpedo which struck the Nevada blew open the blister, original shell, and inner bottom plating even though the last two were backed by fuel oil. The force of the explosion was absorbed by the inner (armored) bulkhead and by the interior decks which stiffened it. In the California, on the other hand, “the top and bottom connections of the longitudinal torpedo bulkheads remained intact,” and the liquid-loaded layers moved together to transmit the force of the explosion to very strong transverse beams which kept the pressure from distorting the innermost (armored) bulkhead. In the California, liquid loading of adequate depth was combined with the necessary internal bracing to both dampen the shock and collect any fragments of outer plating blown inward by an explosion. (See Figure 5)

The damage caused by the torpedo which struck the California aft illustrates one real weakness of the system, a weakness which resulted not from faulty design concepts but from a need to run piping and similar conduits (for electricity or ventilation) through watertight (and otherwise unpierced) boundaries. The war damage report prepared by the Bureau of Ships correctly criticized several instances where piping ran through or too close to the torpedo defense system. The most obvious example was the 8-inch fuel oil filler line which fractured the armored bulkhead between frames 101 and 102 below the first platform. That small rupture led directly to the flooding of the port thrust block room and indirectly to flooding in the center motor room (the next compartment inboard). In this case, the pipe itself shifted, straining the bulkhead through which it passed.

Although the loss of the Nevada can be attributed to faults in her torpedo defense system and to the advanced age of the ship, the California was lost “…because of manholes left open. . . and loose manhole covers on the port side of the third deck and because most of the watertight closure fittings on the third deck and below were open…” The torpedo defense system was in the condition designed for maximum underwater protection. There were no serious flaws in the design or construction of the ship’s underwater defenses. The California sank because a number of manhole covers to voids in the portside torpedo defense layers were off or not tightly secured, the third deck watertight compartments were not sealed, and there were not enough pumps on board the California or available in the harbor to stem the flooding which spread slowly throughout the ship. Where the two torpedoes pushed in the deep torpedo defense layers, water was able to bypass the holding (armored) bulkhead by flowing through the open or loosened manhole covers at the top of void spaces. The water then spread over the third deck. It was not isolated on the third deck portside because “several doors and hatches on the port side of the third deck between frames 30 and 57 “were apparently “open at the time of damage and were not subsequently closed.” A similar situation prevailed in the area of the torpedo damage aft, and, both forward and aft, the incoming witer ran down ventilation trunks to the first platform and, eventually, up through plumbing drains and bomb-damaged ventilation trunks to the second deck.

The Bureau of Ships was not able to ascertain exactly the number of manhole covers off or loose at the time of the attack. As the bureau’s report noted, “Precise information concerning the spread of water throughout the vessel subsequent to damage…is lacking. Evidence relative to initial damage control measures is either missing or incomplete.” However, the statement of the ship’s commanding officer that the manhole covers to three outer and two inner port voids were off at the time of the attack seems on the conservative side. During salvage operations, “…six port covers were found to be missing and twelve covers were found with nuts slacked off.” Whatever the exact number, this weakening of the ship’s defenses was a serious matter, and the justification for it is still not clear. There was no official material inspection scheduled for the California, and the ship’s log did not contain any references to maintenance of the vessel’s protective system. It seems fair to conclude that a minor oversight contributed significantly to the battleship’s sinking. 

Even the very serious effect of water seeping over the defense layers and across the third deck would not have meant the loss of the ship if the third deck had not been abandoned within 15 or 20 minutes of the first torpedo strike. The torpedo which struck the California forward ruptured fuel oil tanks, letting water into the fuel lines. As a result, power for the pumps was lost and the lights failed. Darkness, confusion, and the fumes of the fuel which entered third deck compartments led to the too-rapid evacuation of the third deck, leaving the lower levels of the California all but open to flooding. Fifty minutes after the attack began, the engineering and electrical departments were able to isolate the water in the fuel supply to the forward piping system , and electrical power and hydraulic pressure were restored by two of the four aft boilers. At about the same time, a 250-kilogram bomb struck the starboard side of the ship on the upper deck at frame 59 . That bomb, like one which did similar damage to the Nevada, was repelled by the armored (second) deck, but it did start a serious fire which, because it could not be controlled, hampered “…efforts to close the vessel on second and third decks between frames 48 and 75. ” The heavy smoke from this fire was drawn down into the forward engine room, disrupting efforts to clear the forward fuel line of water, and the oil fires which enveloped the ship at 1000 forced the crew to evacuate the vessel entirely. By the time the crew began returning to the battleship at 1015 , the situation was beyond repair.

Had the manhole covers been secured and had the third deck been closed adequately, there would not have been a need, as historian Samuel Eliot Morison aptly observed, to pump “Pearl Harbor through the ship.” As it was, the California showed “a strong disinclination to sink,” and the presence of pumps like those used eventually to float the ship might have kept the flooding at bay. The Nevada sank because, once the ship’s second deck was below the waterline forward, nothing stood between water entering several large holes in the bow section and the ventilation trunks which led directly to pump and boiler rooms. The California was lost, on the other hand, because there was no watertight integrity below the second deck; the open and loose manhole covers and the cracked joints around piping allowed relatively small amounts of water into the ship, but no flooding boundary could be maintained after the second deck also lost its integrity.

The West Virginia, with the same underwater protective system as the California, was struck by seven torpedoes. Six impacted directly against the ship’s port side, while the seventh slammed into the rudder and blasted it free of its mount. All of the six torpedoes which hit the battleship’s hull struck on or above the West Virginia‘s side armor belt. However, the six explosions did substantial damage to the skin of the vessel above and below the armor belt. Below the side armor, around Frames 46, 70, 81, and 94, the side of the ship was pushed in until the plating split vertically along its riveted joints. The liquid­-filled torpedo defense system was compressed and displaced inward, straining and distorting the innermost holding bulkhead. Significantly, those final bulkheads, though warped in several places, nevertheless held.

The West Virginia did not sink because of a failure in the torpedo defenses built into her. Water rushing into the torn side of the ship produced a rapid list, so that one torpedo, fired after the first four, struck the top of the armor belt near Frame 81. The sixth torpedo to strike the battleship’s hull impacted above the armor belt at Frame 74 amidships. This last torpedo, and the one which hit the top of the side armor at Frame 81, tore up the upper, unarmored portion of the West Virginia‘s side from a point just aft of turret 2 to nearly the break of the upper deck.

The inrush of water resulting from these two latter hits probably contributed more, than any other single factor, to the sinking of the West Virginia, by flooding across and down through the second and third decks. 

These last two torpedoes also caused the structural damage apparent in the photographs of the battleship: “The shell and vertical frames were demolished between Frames 64-74, and 77-82, which allowed a general collapse of the superstructure, upper and main decks.” The damage done by the torpedoes was worsened by oil fires which burned in and around the bottomed battleship for 30 hours after the attack, but the extensive destruction of the West Virginia‘s port side should not obscure the fact that the maximum distortion of the ship’s innermost antitorpedo bulkhead was only 18 inches (at Frame 77; see Figure 6). The torpedo defenses of the West Virginia were not breached. Their strength, plus prompt counterflooding and the retarding pressure exerted on the West Virginia by the Tennessee as the sides of the two ships wedged together, kept the West Virginia from capsizing. Similar, though somewhat less, damage to the Oklahoma proved fatal.

Given the evidence, there must be some question about the ability of the Nevada and Oklahoma, even in the most advanced stage of watertightness, to resist successfully the degree of underwater damage which battleships serving as first-line units in 1941 might be expected to sustain. It is not enough to say that these ships were simply too old to withstand the strains of 1940s weaponry, or that they were not in a condition of maximum watertightness on the day of the attack. The torpedo defense system was not deep enough, and the flooding of the empty blister compartments was unnecessarily excessive and too rapid to be counterbalanced safely. In addition, the deficiencies of the Nevada‘s centralized ventilation system, where a single source supplied air to the forward half of the ship and where all boiler rooms were supplied from the same point, had been recognized by the Bureau of Ships for some years. 

This pattern carries over when one considers the comparative strengths of the horizontal armor protection of the same classes. All the battleships attacked at Pearl Harbor had at least two armor decks, with the stronger–designed to break up or detonate heavy shells–placed on top of the thick side armor belt. The lower armor deck, usually thinner, was the next deck beneath the main armor deck. Its purpose was to stop any splinters which might break through the deck above. The Tennessee and Maryland classes had not been modernized during the 1930s, but the protection given them originally was substantial: two layers of 70-pound special treatment armor steel (STS) had been laid together to form the second deck (3 1/2 inches thick), while the third deck was composed of an upper layer of 40-pound STS and a lower layer of 20-pound medium steel plates (1 1/4 inches thick). The Nevadas and Pennsylvanias had had their protection augmented during modernizations. Their second decks had four layers in all: an 80-pound STS layer on top, a 50-pound STS layer beneath it, and then a section of 50-pound nickel steel plates, and, on the bottom, a layer of 50-pound medium steel, for a total armor thickness of 4 1/2 inches. The third decks of these classes were of 40-and 60-pound nickel steel laid above a layer of 20-or 30-pound medium steel, and these decks (2 1/2 inches thick) angled down at their outer edges to join the bottom of the side armor belt.

The decks originally fitted to the Tennessee and Maryland classes were not thought strong enough by the Bureau of Ships in 1941 to resist large (1,000-­pound) armor-piercing bombs dropped from high altitudes, but the protection given these classes as built was superior to that possessed by the Nevadas and Pennsylvanias as modernized.  The problem with the thicker decks of the latter classes was that they were too crisscrossed by the joints of the many different types of armor plate which composed them. So although their decks were thick, they were not correspondingly strong. In addition, the decks of the Nevada and Pennsylvania classes were simply not thick enough, despite the additions which had been made to them during their modernizations. When the California was finally modernized in 1942-43 , 120-pound STS plates (3 inches thick) were added to that ship’s second deck in the vicinity of the vessel’s magazines, giving the California a protective shield which armor-piercing bombs supposedly could not break through. The four-layer second decks which the Nevadas and Pennsylvanias carried in 1941 were slim indeed by comparison.

The West Virginia was struck by two armor­-piercing converted shells. The first, after striking the foretop, carried through two levels of the bridge (searchlight platform and signal bridge), penetrated the superstructure and main decks at about frame 70, and finally came to rest on the second deck, port side, without exploding. The second shell broke through the top of number 3 turret, came apart, but did not explode. The damage caused by this bomb was limited: both seaplanes mounted on the turret’s catapault were wrecked, and gasoline from one of the aircraft ignited, although the fire which followed was not severe. The point here is that a properly fuzed converted projectile did not penetrate the West Virginia‘s armor deck; instead, the deck halted the shell, even though the protection offered by a deck of that thickness was known to be limited.

The Tennessee and Maryland were also struck by the converted shells, and, as in the case of the West Virginia, damage was superficial or minor. The Maryland, struck by two such shells, had portions of her forecastle deck ripped up by the splinters from one, while splinters from the second caused numerous small leaks in her bow near Frame 13. Of the two projectiles which hit the Tennessee, one broke through the armored top of turret 3 while the other detonated on the middle gun of turret 2. The former broke apart after crashing through the turret’s roof, and the portion of its explosive filler which did ignite burned out only one of the three gun chambers in the turret. The latter briefly jammed the guns of turret 2 and cracked the barrel of the center gun.

The official evidence suggests that, of the 49 or 50 (accounts differ) converted armor-piercing shells dropped by the first wave of horizontal bombers on the stationary battleships, only about eight hit targets. Of these, at least two broke up upon impact, one was a dud, and one went off before penetrating even a light deck. Overall, the performance of these shells was not impressive, and there must be some question how one of them could have caused the destruction of the Arizona. There can be no doubt that the forward main magazines of the Arizona exploded; the question is whether the explosion resulted directly from a converted projectile which eyewitness accounts said fell near the forward turrets.

One official explanation is that an “…armor-­piercing bomb…penetrated to the black powder magazines, setting off the smokeless powder magazines…which destroyed the ship forward.” Both the black powder and main battery powder bag magazines of the Arizona were located on the ship’s first platform deck, roughly 30 feet below the level of the upper deck, and both were shielded by the second (armor) and third (splinter) decks. The attention given to the black powder magazine by Navy investigators resulted from the highly combustible nature of black powder. Given the small bursting charge (66.5 pounds) of the converted 40-centimeter shells, one could argue that only a hit amidst such quick burning powder was sufficient to touch off the main magazines. The Arizona‘s black powder magazine, quite small when compared to the six 14­inch smokeless powder magazines nearby, did contain, apparently, enough cans and charges of black powder to trigger a much larger explosion. Hence, one possible explanation of the destruction of the Arizona is that it was a fluke, caused by a chance hit on a highly incendiary magazine.

However, if the bomb which struck the Arizona fell at about the same angle (75°) and from approximately the same direction (30° on the starboard bow) as the bomb which struck the center gun of the Tennessee‘s number 2 turret, then it is doubtful that the Arizona was destroyed by an explosion which first occurred in the black powder magazine and then spread to the main powder storage. The black powder magazine of the latter was located just behind and partially below the barbette of the forward turret. To reach that compartment, a bomb would have had to avoid the side and roof of number 1 turret, as well as the armored tube of the barbette. To do that, the bomb would have had to fall either at a relatively shallow angle (55 to 60°) or nearly perpendicular to the longitudinal axis of the ship. Neither event was likely because of the height and approach angle of the Japanese bombers. (See Figure 7)

There is another possibility. There was an armored hatch from the third deck (compartment A-511) of the Arizona to a passageway (A-416) directly adjacent to the ship’s black powder magazine (A-415-M). If that hatch had not been closed the morning of the attack, and if a bomb (or flash and fragments from a bomb) had penetrated the second deck, and if there were highly inflammable materials in that passageway, then one of the converted 40-centimeter projectiles might well have initiated a flash which ultimately reached the battleship’s main magazines. The performance of the other shells suggests none could have penetrated both armor decks of even the Arizona. Hence, it is possible that the third deck was in fact not tight and that some incendiary material was placed near the foot of the companionway in passageway A-416. In 1944, the Bureau of Ships decided that in fact something similar to this had probably occurred. (See Figure 8)

The condition of the sunken Arizona indicated that the pressure of the forward magazine explosions had been vented through the sides of the ship and through the deck forward of number 1 turret:

Beginning at about Fr. 62, port and starboard, the sides of the ship from the top of the armor to the upper deck began to bulge outward; and proceeding forward, this bulging and tearing away from the internal structure is increased so that between Frs. 50 and 10 the sides were blown outward almost to a horizontal position…

From the base of the funnel to the first barbette, the Arizona‘s decks sloped downward, so much so that what remained of the upper deck rested on top of or just below the battleship’s side armor belts. In the area just forward of the first barbette, the upper, main, and second decks were all thrown forward and up, and the structural material which was not blown away was smashed or buried in the mud of the ship’s mooring.

The sinking of the Arizona suggests why the Japanese went to great lengths to give their first­wave horizontal bombers at least one run over the stationary battleships before the dive-bombers attacked. At first glance, however, the torpedo attack appears to have been more successful: of 40 torpedoes carried, at most 17 found targets (13 against the battleships), for a rate of success of just over 40%. Of the 50 converted shells, a maximum of eight struck home, for a rate of success of only 16%. But all the torpedoed battleships were raised and repaired except the Oklahoma, whereas the only battleship hit with effect by the converted shells was quite literally smashed. The final score for both weapons was the same: one battleship which was not returned to serv­ice. The converted shells were an all-or-nothing weapon; either they would do very little damage, or they would completely wreck a battleship.

The material damage done to the battleships during the Pearl Harbor attack was great but not really greater than what was to be expected under the circumstances. The passive defenses of the Nevada and Pennsylvania classes were recognized as flawed, and it is probably true that these warships would have been lost had they been heavily attacked on the open sea. The same cannot be said, however, for the Tennessee and Maryland-class battleships, which withstood punishment rather well for their ages. An interesting point is that only four years divided the dates for the authorization of the Nevada and Tennessee classes. The advances in design and engineering achieved in that short period made the difference between survival and destruction when these ships were attacked with weapons of the 1940s. True, the West Virginia and California did sink, but the former did not capsize. She sank only after sustaining damage no battleship of her type (and condition) could have survived. The California, on the other hand, was the victim of confusion and operational errors.

The defeat of the battle line by Japanese forces at Pearl Harbor did not result mainly from deficiencies in the design of American warships. The battleships, unprepared and poorly defended, in several cases absorbed major damage while in a very reduced stage of watertightness. Damage control efforts were necessarily confused and, consequently, often haphazard. The results of the attack might well have turned more to the advantage of the Imperial Japanese Navy. The West Virginia, for example, might have rolled over, or the forward main magazines of that ship, which were not flooded , might have exploded, turning the West Virginia into another Arizona. The American battleships were all old; several were nearly overage; most were overweight. None of the battleships in Pearl Harbor was a first-line warship in a material sense; all had recognized deficiencies. But a few significant omissions (no antitorpedo nets or baffles, inadequate firefighting equipment, and the lack of wartime standards for watertight integrity) resulted in sinkings instead of serious–but acceptable­–damage.

Indeed, the designs of the underwater protective systems of the Tennessee and Maryland classes were considered basically sound by the Bureau of Ships even after the Pearl Harbor attack. When the five vessels of these two classes were modernized or adapted for war service, their torpedo defense systems were widened, but for stability reasons. All five were overweight, and all needed greater freeboard and an increased ability to resist an initial heavy list in the event of damage. Only the horizontal protection of these two classes was considered lacking. Internal modifications were made to the Pennsylvania and Nevada, but, again, the purpose was to strengthen what was considered to be an acceptable design. The Pennsylvania, for example, retained her basic prewar form through most of 1942. The most apparent alterations carried out on the older battleships after Pearl Harbor were those to the ships’ superstructures, the visible consequences of which were often dramatic. Antiaircraft armament was altered and often drastically increased, and cage and tripod mainmasts were cut down or eliminated. However, the passive defenses of the ships remained basically the same, indicating the confidence of the Bureau of Ships in design work done, in some cases, several decades before the attack which tested them.

 
 
 
  • Steve Barcomb

    Great read thanks!

  • Jim Valle

    The article doesn’t mention the characteristics of the Japanese torpedoes. Didn’t they have unusually large warheads? Probably larger than the men who designed the protective systems anticipated.