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Pearl Harbor


Aerial photograph of Pearl Harbor before the attack
U.S. Navy

American officials claimed that Pearl Harbor (157.961W 21.354N) was the most heavily defended fortress in the world. That claim died on 7 December 1941, when a surprise Japanese carrier strike inflicted severe damage on the U.S. Pacific Fleet and plunged the United States into the Second World War. Nevertheless, the coastal artillery around the harbor were impressive, including six battleship-caliber batteries, eight cruiser-caliber batteries, and 12 smaller batteries along with 26 fixed 3" antiaircraft guns, 60 mobile 3" antiaircraft guns, 20 37mm antiaircraft guns, and 107 0.50" antiaircraft machine guns . These were all under Army control, with headquarters at Fort Kamehameha (157.95W 21.32N), and were manned by 15, 16, and 251 Coastal Artillery Regiments. The largest guns could be directed against any point on the Oahu coast. However, the guns were not manned on that fateful Sunday morning, and did not fire a shot during the attack. The Oahu garrison consisted of about 25,000 men of the recently triangularized 24 and 25 Divisions, which were as well trained at that time as any in the Army. The Hawaiian Air Force boasted 154 fighters (although only 99 were of the most modern type, the P-40) and 57 bombers (of which 24 were modern B-17s and A-20s). There were also five newly installed radar stations on the island (SCR-270B model), though the fighter control center was not yet fully operational. A conventional attack from the sea would in fact have had a very rough time.

The harbor itself was not considered a serious candidate for a major base until the 1930’s, though a small naval station was established as early as 1901. Geographically, Pearl Harbor is actually a drowned river delta within a barrier reef, shallow and with a single narrow entrance. While the latter had some advantages for antisubmarine defense, it also meant that it could take hours for the Pacific Fleet to sortie. By 1941, the harbor had extensive facilities, including dry docks, machine shops, and oil storage equal to that of the entire Japanese Empire (563,000 tons in 54 tanks) — none of which were damaged in the attack. The shipyard alone had an area of 498 acres (371 hectares). The harbor was still in the process of being dredged, but there was enough deep anchorage for a hundred warships, so long as there was no objection to anchoring them in close clusters.

The shipyard was served by multiple power plants, include a brand-new 20 megawatt bombproof plant.

By the time the war ended, oil storage at Pearl Harbor had been more than doubled, to nearly 1.4 million tons. This included the secret Red Hill Underground Fuel Storage Facility, begun in December 1940, with the first of 20 41,000-ton vaults completedin October 1942 and the last completed in September 1943.

The Pearl Harbor attack


  1. The Japanese Plan.
  2. Pearl Harbor Defense.
  3. The Attack.
  4. Aftermath.
  5. Responsibility for the disaster.


Japanese view of the attack
Naval Historical Center #NH 50931

So far as the American public was concerned, the Pacific War began on 7 December 1941 with the surprise carrier attack on the naval base at Pearl Harbor. However, the Japanese Army began landing in Malaya about two hours earlier, as the opening move of their Centrifugal Offensive. These landings came as no surprise, since both British and American intelligence were tracking the movements of troop convoys south. They may have helped draw attention away from the Central Pacific and thereby contributed to the success of the Pearl Harbor strike.

The Japanese Plan.

The Pearl Harbor operation was conceived by Yamamoto Isoroku, commander of Combined Fleet, which included most of the warships of the Japanese Navy. It is not known when Yamamoto first came up with the idea, but his friend and chief of staff, Fukudome Shigeru, first heard Yamamoto suggest an attack on Pearl Harbor in March or April 1940. Though opposed to a war against the United States, Yamamoto felt that if war was unavoidable then Japan's only hope was a devastating  surprise attack on the U.S. Pacific Fleet at the moment war broke out, which would allow Japan to seize and consolidate the resource-rich areas of southeast Asia and the southwest Pacific and force the Allies to accept a negotiated peace.

The notion of a surprise raid on Pearl Harbor at the start of a war against the United States was not new, having been wargamed as early as 1927 by the Japanese Naval Staff College. Nevertheless, Yamamoto's concept was highly unorthodox. Japanese naval doctrine had long focused on a Great Decisive Battle to be waged between U.S. and Japanese battleships somewhere close to Japan, in the manner of the decisive Battle of Tsushima of the 1905 Russo-Japanese War. And, as a fleet commander, Yamamoto was supposed to conduct training and carry out operations planned by the Navy General Staff. But Yamamoto pressed on with conceptual study of a Pearl Harbor attack, and by December 1940, following the annual fleet maneuvers, he had decided that the operation must become part of the war plan.

Detailed planning was left to Commander Genda Minoru, the extremely talented air officer of 1 Carrier Division. Genda immediately saw the possibilities (and the challenges) of the plan, and pressed for carriers and cruisers to be the priority targets. Genda also wished to make Oahu the principle target of the Japanese opening offensive, in order to deprive the Americans of their most valuable Pacific base. However, his proposal for an amphibious assault on the island was rejected at once by Onishi and certainly would not have had the support of the Army. Genda completed a draft operational plan by February 1941.

Curiously, once the idea of seizing Oahu was rejected, Genda put no further emphasis on destroying the base itself. The target was the Pacific Fleet and its supporting air power. Nor had Yamamoto envisioned Pearl Harbor itself as a target. Yamamoto's real target was American public opinion: By destroying the Pacific Fleet's battleships, the symbol of American naval power, Yamamoto hoped to strike such a devastating blow against American morale that the pacifist and isolationist elements of the American public would demand a negotiated settlement favorable to Japan. To achieve this, he was willing to risk heavy losses to his carrier fleet. As Onishi later recalled, Yamamoto believed (Zimm 2011):

Most Americans — like most Japanese — still believed battleships to be the mightiest weapons of war. The sinking of one or, better yet, a number of these giant vessels would be considered a most appalling thing, akin to a disaster of nature. Such destruction, Yamamoto reasoned, would paralyze the vaunted Yankee spirit.

Surprise and secrecy were considered vital to the success of the attack, but there were leaks that might have proven disastrous for the Japanese if the Americans had not discounted them. On 27 January 1941, the American ambassador to Japan, Joseph Grew, sent a telegram to the State Department reporting that he had received a report from the Peruvian ambassador that the Japanese planned to attack Pearl Harbor in the event of war. Grew considered the report fantastic, and so did Navy intelligence, and nothing further was done with it. The Peruvian ambassador seems to have gotten his information from his Japanese cook, and it is unclear how the cook came by the information, assuming he had any actual knowledge. The notion of an attack on Pearl Harbor had been a cliché of Japanese writers for years before the war, and the cook may simply have been repeating the cliché.

The Japanese plan initially called for an attack by a carrier force of three fleet carriers. Following table top maneuvers on 9 October 1941, Yamaguchi, Kusaka, and Genda became convinced that all six of Japan's fleet carriers should be committed to the operation. The three officers persuaded 1 Air Fleet commander Nagumo to send Kusaka to ask the Navy chief of staff, Nagano, to approve a six-carrier strike. Nagano did so following discussions with Kusaka on 18 October. The six carriers would be able to launch two attack waves totaling over 300 aircraft against Pearl Harbor while maintaining a strong combat air patrol over their own carrier force.

Because Pearl Harbor is relatively shallow (just 40 feet or 12 meters deep over most of the channelfar,) the Americans believed that aerial torpedoes could not be successfully employed against their fleet, and the harbor was not protected by torpedo nets. However, the Japanese modified aerial torpedoes for use in the attack with wooden fins designed to ensure a shallow run. Tests showed that a bomb weighing 800 kg (1760 lbs) would penetrate battleship deck armor if dropped from an altitude of 12,000 feet (3660m). The Japanese were short of the special steel required for such weapons, but found they could convert 16" (406mm) armor-piercing shells to make effective bombs. Designated the Type 99 Number 80-3, the converted bombs were streamlined to improve penetration and carried 22.8 kg (50 lbs) of high explosive. However, production was slow and only 150 of the bombs had been completed by mid-September 1941, while the last of the specially modified torpedoes were finished barely in time to be rushed to the task force rendezvous by carrier Kaga.

The aircrew were painstakingly trained for their mission. The first attack wave included a total of 89 B5N "Kate" torpedo bombers, of which 49 were configured as horizontal bombers, from Akagi, Kaga, Hiryu, and Soryu; 51 D3A "Val" dive bombers from Shokaku and Zuikaku; and 45 A6M "Zero" fighters drawn from all six carriers. The fighters and dive bombers were to attack the airfields while the torpedo and horizontal bombers were to concentrate on the carriers and battleships. The second wave consisted of 54 "Kates" from Shokaku and Zuikaku configured as horizontal bombers and 80 "Vals" and 36 "Zeros" from the other four carriers. The inexperienced torpedo bomber crews from Shokaku and Zuikaku, which had just commissioned, were given the relatively easy assignment of bombing the airfields, while the rest of the second wave were to finish off any damaged warships. The attack waves were to thoroughly wreck the largest warships and not spread their attacks, since moderately damaged vessels would be relatively easy for the Americans to salvage, and the dive bombers of the second attack wave had specific orders to wreck the exposed hulls of any capsized aircraft carriers.

There were disagreements at different levels of the command chain on what the priority targets should be for the raid. The formal order from Navy General Staff for the operation designated the American land-based air power as the first priority, followed by carriers and then battleships. This likely reflected the fears of Navy General Staff that Nagumo's force would be highly vulnerable to an American counterstrike. Yamamoto ignored this in his own order to Nagumo, which gave top priority to disabling four battleships and second priority to disabling four carriers. However, Genda felt strongly that the carriers should be the priority target, and there are clear indications that his thinking strongly influenced how the operation was planned and executed.

In addition to the carrier strike force, the Japanese deployed a large submarine force around Oahu with orders to pick off any ships that fled Pearl Harbor. Five of these submarines carried midget submarines that were to penetrate the harbor defenses and wreak what havoc they could. This ill-advised plan accomplished nothing while nearly giving away surprise, since one of the midget submarines was detected and sunk by the destroyer Ward an hour and a half before the carrier raid conducted its first attacks. However, the report of the sinking was slow to reach higher command, and its full significance was not realized until too late. Ironically, the submarine force, which led the Japanese forces out of harbor and to war, sailed on the eleventh minute of the eleventh hour of the eleventh day of the eleventh month — the same time that the armistice went into effect ending the First World War.

To conceal their intentions, the Japanese imposed strict radio silence on Pearl Harbor Attack Force; changed their call signs on 1 December 1941, only a month after the previous change; and retransmitted old messages to maintain the impression of an unchanged volume of signals. American intelligence recognized that older signals were being retransmitted, but failed to guess their significance.

Pearl Harbor Defense.

The Pearl Harbor Naval Base was under the command of Vice Admiral Claude Bloch and the Army garrison was under the command of Lieutenant General Walter Short. Short was highly regarded but seems to have been confused about his mission. His force was in Hawaii to protect the Fleet at its base, but he seems to have thought the Fleet was there to protect Hawaii. Short also was obsessed with sabotageand less concerned with the possibility of an air raid. His orders to park the aircraft in neat rows in the centers of the runways, rather than leave them dispersed in their revetments where more manpower was required to guard them, left the aircraft highly vulnerable to air attack. However, the entire U.S. high command was obsessed with sabotage, since German fifth columnists had been active during the early Nazi triumphs in Europe.

Kimmel organized the Pacific Fleet operationally into three task forces under Pye, Halsey, and Brown. He was unable to keep more than one task force at sea at a time due to a shortage of oilers; the Pacific Fleet had only eleven, of which just four were equipped for underway replenishment, due to the transfer of support ships to the Atlantic. On the morning of the attack, Halsey was returning from an aircraft ferry mission to Wake with approximately half his force, while the other half was preparing to fly off aircraft to Midway. The third Pacific Fleet carrier was at San Diego for refitting, and, as a result, all three carriers of the Pacific Fleet were absent from the harbor and were spared the attack. However, Brown was leading a small exercise at Johnston Island, leaving most of his force and almost all of Pye's force at the base.

The attack caught the Army at a particularly bad time. Short had had his troops at a high state of alert in the weeks before the attack, but chose the weekend of the attack to let his men stand down, rest up, and carry out maintenance on their equipment (quoted by Zimm 2011):

During the week proceeding [sic] 7 December, the entire Hawaiian Department, by order of General Short, engaged in a full-scale exercise for seven consecutive days. Army units from Schofield Barracks deployed, antiaircraft units drew ammunition and set up stations all over the island, and the Hawaiian Air Force armed aircraft and dispersed them to protective revetments. The warnings center was fully operational and launched aircraft against simulated attacking targets....

... On Saturday, 6 December, we were told to take down all arms and lock [them] in [the] Armory and take our passes to Honolulu.

The sixty mobile 3" antiaircraft guns were parked away from their firing positions and had no ammunition. The stand down also explained the low Army aircraft availability that morning: Of 231 Army aircraft on Oahu, some 88 or 38% were under repair or maintenance at the time of the attack. Had the Japanese attacked the previous weekend, they would have encountered a garrison prepared to rapidly man its guns and sortie its aircraft.

Another unfortunate decision was to operate the Aircraft Information Center only in training mode until after war broke out, because Short and Kimmel felt they could not spare the officers to run it until then. This deprived Oahu of its best chance of a timely warning of the Japanese strike.

The Attack.

The encounter between Ward and the midget submarine was not the only warning the Americans missed. The Japanese launched a pair of seaplanes in advance of the first attack wave to reconnoiter Pearl Harbor and Lahaina Roads, an ill-advised move given that the strike force had little time to take advantage of their report and their presence might have given away surprise. The U.S. Army radar sets were being operated from 0400 to 0700, but the associated fighter direction center was not yet fully set up and its personnel were still being trained. When the radar operators at Opana Point, on the north shore of Oahu, picked up a large formation of aircraft approaching from the north just after 0700, the only officer still present at the fighter control center dismissed the sighting as a flight of American B-17s due in from the mainland. For security reasons, he did not explain this to the radar operators, and thus denied them the opportunity to report that this formation consisted of at least 50 aircraft, far more than the number of B-17s being expected.

At 0749, the Japanese air strike commander, Fuchida Mitsuo, sent out the attack signal, "To, to, to" (from the first syllable of totsugekiseyo, "charge"). This was picked up by the sensitive radio receivers of Nagato, Yamamoto's flagship in the Inland Sea. By 0753, Fuchida had sighted the harbor, saw no indications of American fighters or antiaircraft fire, and sent out the code words for success, "Tora! Tora! Tora!" ("Tiger! Tiger! Tiger!") This was received on Akagi, where even the Zen Buddhist, Kusaka, was moved to tears, and silently shook hands with Nagumo.

Fuchida had prepared two attack options, depending on whether surprise was achieved. In the event of complete surprise, he would fire a single smoke signal from the cockpit of his aircraft, indicating that the torpedo bombers should attack first, before the Americans were alerted. The dive bombers and fighters would then carry out their airfield attacks. If surprise was lost, Fuchida would fire two smoke signals, indicating that the fighters and dive bombers should attack first and attempt to distract and suppress the American antiaircraft defenses before the vulnerable torpedo bombers made their runs. Fuchida accordingly fired a single smoke signal for the surprise option, but his signal was missed by the torpedo aircraft. When Fuchida saw that they were not deploying for the attack, he felt compelled to repeat his smoke signal. Both smoke signals were seen by the fighters and dive bombers, which assumed surprise had been lost and immediately deployed for attack. The result was chaos. The first aircraft to reach their release point were dive bombers assigned to attack Ford Island, and the explosion of their bombs gave the Americans perhaps four or five minutes warning before the torpedo bombers reached Battleship Row. This may have prevented an even greater catastrophe for the Americans.

Although the Japanese had fresh intelligence that the American carriers were out of the harbor, a second group of torpedo bombers approached Ford Island from the west to attack the carrier and cruiser moorings, in case any of the carriers were present after all. (In fact, Enterprise should have arrived back in harbor before the attack, but was delayed by heavy seas.) There were few worthwhile targets here, but several torpedo bombers mistook target ship Utah for an operational battleship and hit her with two torpedoes. A third torpedo aimed at Utah hit the old light cruiser Raleigh. Utah quickly capsized, while Raleigh was saved by expert damage control. The remaining torpedo bombers headed for the navy yard in search of better targets, mistook ancient minelayer Oglala alongside modern cruiser Helena for a single battleship, and put a torpedo into Helena that badly damaged her and capsized Oglala.

Most of the torpedo bombers approached "Battleship Row" from the direction of East Loch, an arm of the harbor that conveniently led directly to the southernmost battleship moorings on the east side of Ford Island.  A few American guns opened up as the torpedo bombers made their attacks, but most of their torpedoes had already been launched before the Americans were fully alerted, and the American battleships were sitting ducks. The brunt of the attack fell on Oklahoma and West Virginia, which were anchored directly across from East Loch and were each hit by several torpedoes. California was also a fairly easy target and took two torpedo hits, but Arizona and Nevada were far enough north of East Lock to make rather difficult targets. Arizona was also partially shielded by repair ship Vestal moored outboard of her. Nevada took a single torpedo hit and Arizona was missed by the few torpedoes launched at her. Tennessee and Maryland were moored in pairs with Oklahoma and West Virginia and were thus shielded by their sister ships, while Pennsylvania was in dry dock for routine maintenance.

The attack by the horizontal bombers followed within a few minutes. Genda and Fuchida had put great stock in the horizontal bombers for attacking the inboard battleships, and their efforts were rewarded when an armor piercing bomb penetrated the forward magazine of Arizona and touched off a catastrophic explosion. However, the remaining hits (a second hit on Arizona and two hits each each on Tennessee and Maryland) failed to inflict significant damage, in part because a large percentage of the bombs were duds. Vestal was hit by an armor piercing bomb that passed clear through her to explode on the harbor bottom.

Meanwhile the dive bombers and fighters bombed and strafed the American airfields at Wheeler, Hickam, Bellows, and Ewa, destroying or damaging most of the American aircraft on the ground. Because the Japanese achieved almost complete surprise, only a handful of American fighters made it off the ground. Two fighters from Haleiwa were able to make it into the air undetected, apparently because Haleiwa was a new airfield which Japanese intelligence had missed. The Haleiwa pilots, George Welch and Kenneth Taylor, were able to shoot down six Japanese aircraft. American pilots managed to make a total of fourteen sorties during the attack, which shot down eight to eleven Japanese aircraft at the cost of two of their number. Another two fighters were shot down by the waiting Zeroes immediately after taking off. This was a remarkable performance given that the Americans were outnumbered three to one by the Japanese fighters.

Only two of the Army antiaircraft batteries around the harbor came into action, firing just 116 3" rounds (but claiming two aircraft shot down.) This left the defense of the warships to their own antiaircraft guns, which began putting up a considerable volume of increasingly accurate fire. Unfortunately, by then the worst damage had been done. The second Japanese attack wave found the defenses alerted and the main targets obscured by smoke and fire and inflicted relatively little damage. Many of the dive bombers, which were equipped with general purpose bombs incapable of doing significant damage to battleships, were nonetheless directed against battleships. In particular, some 14 dive bombers went after Nevada as she attempted to navigate the channel to the open sea. Not only were the weapons inappropriate for the target, but the claim (accepted uncritically by most historians) that she would have blocked the channel has been exploded by Zimm (2011) who points out that the channel was 1200' (370m) wide and a battleship is only 600' (180m) long.

Aftermath of the raid
Naval Historical Center #80-G-19930

American losses were very heavy. The magazine explosion suffered by Arizona destroyed the forward part of the ship, and she quickly went down with most of her crew. Oklahoma took numerous torpedo hits and capsized before she could be counterflooded. Both battleships were complete losses. Battleships West Virginia, California, and Nevada all settled to the bottom of the shallow harbor (the Nevada after attempting to sortie through the narrow harbor entrance) but were eventually raised, repaired, and saw combat later in the war. Tennessee was lightly damaged in the attack itself but badly damaged by flaming oil from Arizona, while Maryland and Pennsylvania were only lightly damaged. These three ships were fully repaired within three months of the attack.

The two torpedoes that hit California failed to penetrate her torpedo defense system. However, she had ten or twelve access hatches to her torpedo defense voids opened for inspection, which allowed water to flood freely into the ship. Nevada likewise was hit by a single torpedo did not quite penetrate her torpedo defenses but sprung several seams. A subsequent bomb hit started a fire near her forward magazine, and when orders were issued to flood the magazine, the rear magazine was mistakenly flooded as well. Combined with her poor material condition (many "watertight" seals proved inadequate) and a design flaw in her "Bull Ring" ventilation system, this was enough to force her to beach in sinking condition.

In addition to the battleship casualties, a target ship and two destroyers were lost and three light cruisers, a destroyer, a minelayer, a repair ship, and a seaplane tender damaged. Of the 223 Army combat aircraft on Oahu, 62 were destroyed and 82 damaged. leaving just 77 combat ready. Of these, only 27 were modern fighters. The Navy lost 87 combat aircraft, most of them Catalina patrol aircraft. Personnel casualties totaled 2403 killed or missing and another 1178 wounded. Almost half of the dead were on the Arizona.

Japanese losses amounted to just 29 aircraft (9 fighters, 5 torpedo bombers, and 15 dive bombers) and 55 aircrew, in addition to the five midget submarines, none of which made it back to their mother ships. One of the midget submarine commanders was captured and become the United States' first prisoner of war of the Second World War.

Nagumo has been severely criticized by historians for failing to launch additional attacks to destroy the repair facilities and oil storage around Pearl Harbor. Nimitz later estimated that the loss of the fuel oil would have lengthened the war by two years. However, Nagumo's operational orders were flawed in not designating these as priority targets in the first place. In fact, during the war game rehearsals of the attack, many of the planners stressed the importance of a quick getaway following the initial strikes. Tomioka Sadatoshi, chief of the Operations Section of Navy General Staff, had told Nagumo to get his ships home at all costs. In any case, the effects of an attack on the facilities may not have been so great as postwar historians believed. Zimm (2011) has concluded that a third wave attack concentrated on the Navy Yard would not have destroyed more than 12% of the facilities even under the most optimistic assumptions, while the oil tanks would have been relatively easy to replace.

Nagumo was also worried about being ambushed by the missing American carriers, a fear that was not entirely unreasonable considering what would later happen at Midway. Nor was Nagumo alone in his desire to make a quick getaway. The decision was supported by Kusaka, who had felt all along that 1 Air Fleet belonged with the main operations in Southeast Asia. Even some of the flight leaders, who were disappointed that the American carriers had not been located, wished to withdraw to prepare for a showdown with the American carrier force.

The Japanese were able to accurately estimate the damage done in their raid, both from observations during the raid itself and from a reconnaissance flight on 17 December by a seaplane from submarine I-7, which managed to scout the harbor and return safely to its mother ship.

Because the attack was tactically an overwhelming success, most historians have uncritically regarded it as a model of security, planning, training, and execution. But this may be a classic example of a post hoc, ergo propter hoc logical fallacy. The many Japanese naval officers opposed to the operation had credible reasons for their opposition. Zimm (2011), an expert on operational research, has recently written a scathing critique of the operation, arguing that its success was the result of an astonishing lack of preparation on the part of the Americans and substantial luck on the part of the Japanese. Had the Japanese been less inflexible, for example by reallocating the torpedo bombers assigned to target the carrier moorings once it was known the carriers had left harbor, the attack could have been an even greater disaster for the Americans. Contrariwise, had the Americans properly dispersed their aircraft and had warning of the attack, it could have been a disaster for the Japanese.

Propaganda poster invoking the Pearl Harbor attack
Naval Historical Center #NH 72273-KN

Aftermath.

Though the attack was an undoubted tactical triumph for the Japanese, it is questionable that its strategic value was worth its political cost. The old battleships lost were already in the process of being replaced with modern battleships of the North Carolina class and the majority of aircraft destroyed were obsolescent. The most grievous lost was of trained men. The Pacific Fleet was unprepared for action in the western Pacific even had it been fully intact.  During the Pearl Harbor inquiry, Admiral Kimmel testified that

... I did not think they would attack at Pearl Harbor because I did not think it was necessary for them to do so, from my point of view. We could not have materially affected their control of the waters that they wanted to control, whether or not the battleships were sunk at Pearl Harbor. In other words, I did not believe that we could move the United States Fleet to the Western Pacific until such time as auxiliaries were available, as the material condition of the ships were improved, especially with regard to anti-aircraft, and until such time as the Pacific Fleet was materially re-enforced. I thought it would be suicide for us to attempt with an inferior fleet, to move into the western Pacific.

By contrast, the Japanese had excellent facilities in French Indochina, Palau, and Formosa in close proximity to the target area. However, the attack was a severe blow to American morale, which did not fully recover for almost a year.

The attack caused the American isolationist movement to collapse overnight. On Monday, 8 December 1941, President Roosevelt gave a brief, memorable speech to Congress asking for a declaration of war, and the vote in favor was unanimous in the Senate and had only a single dissent in the House. Pearl Harbor became a battle cry for an enraged America, and guaranteed from the start that there was almost no chance of a negotiated peace with the Japanese, which was their only hope of retaining their conquests from the Centrifugal Offensive. Japan had violated the principle laid down by Clausewitz (Marston 2002):

The first, the grandest, the most decisive act of judgment which the Statesman and General exercises is rightly to understand the War in which he engages, and not to take it for something, or wish to make of it something, which it is impossible for it to be.

From the start, Japan failed to understand the nature of the war it had launched and of the alliance it had united against itself.

Responsibility for the disaster.

The Japanese attack was a risky operation that could have failed disastrously. That it succeeded was due in no small part to an overall climate of unpreparedness in the United States. However, the senior admiral and general on Oahu were immediately relieved of command and forced into retirement, creating an impression that they were principally responsible for the disaster. That they deserved the lion's share of the blame is arguably correct, but there was plenty of blame to go around.

Much attention by historians has focused on the activities of American code breakers at the time of Pearl Harbor. The cryptanalysts had not yet broken the JN-25 naval operational code on 7 December 1941, but were regularly reading the machine-encrypted messages ("Purple") exchanged between the Japanese Embassy in Washington, D.C., and Tokyo. On 6 December, the cryptanalysts decoded the first thirteen parts of a 14-part message that was the Japanese government's reply to the latest statement of the American position. The 14th part arrived the next morning and was decoded just hours before the Pearl Harbor attack. The Japanese ambassadors were instructed to deliver this message to the American government at precisely 1:00 PM Washington time, corresponding to 8:00 AM in Hawaii.

The 14-part message has been characterized as a declaration of war, but it was much more ambiguous than that. The message simply repeated Japan's position, rejected the American position, and expressed the view that further negotiation seemed pointless. While this was certainly ominous, and its significance was not lost on the American cryptanalysts or administration, the note did not formally declare war or even present an ultimatum. Nevertheless, war warnings were sent to all Pacific commands. The message to Hawaii could not be sent by radio due to poor atmospheric conditions, and was sent as a telegram instead. However, the responsible communications officer failed to mark the telegram as urgent, and it did not reach the Hawaii commanders until the attack was long over.

The Japanese Embassy also mishandled its communications. The 14-part message was considered so sensitive that the usual embassy typists were not to be permitted to see it, and a clean copy was not ready in time for the 1:00 appointment. Tokyo had emphasized the sensitivity of the message without explaining its urgency (the Japanese ambassadors were in the dark regarding Japanese military plans, and did not themselves seem to view the message as a declaration of war) and the message was not delivered until 2:30 PM, when the attack on Pearl Harbor has been underway for almost an hour and a half. Had everything gone according to plan, the message would have been delivered at 8:00 Hawaii time, and the first wave of the Pearl Harbor attack would have arrived half an hour later. It seems likely that the Japanese would then have claimed that their "declaration of war," however ambiguous, had been delivered before the opening of hostilities; but the message was delivered late, the first wave of the Pearl Harbor attack arrived early, and hostilities commenced an hour and a half before anything that could be described as a declaration of war was delivered to the American government.

The British likewise were not presented with an unambiguous declaration of war until well after the initial landings in Malaya. It was not until nearly eight hours after the Pearl Harbor attack commenced that formal declarations of war were handed to the American and British ambassadors in Tokyo.

Recently, Japanese historian Iguchi Takeo has cast further light on the 14-part message with the discovery of Japanese archival material showing that the Japanese Army and Navy insisted that the language of the 14-part message be toned down to deliberately avoid giving any warning of the attack on Pearl Harbor. He further speculates that the transmissions to the Washington embassy from the Tokyo Foreign Office were deliberately garbled to ensure that the embassy staff would be unable to deliver a clean copy to the Americans before the attack took place.

Charges that the Roosevelt administration deliberately allowed the attack to take place, in order to draw the U.S. fully into the Second World War, began to be made almost as soon as the war ended. These charges are baseless. There is considerable evidence that Roosevelt hoped to provoke an incident that would justify a declaration of war — but in the Atlantic, against Germany, which was rightly seen by U.S. military planners as the more dangerous enemy. In hindsight, there was intelligence indicating the possibility of an attack on Pearl Harbor, but there is no credible evidence that anyone connected the dots at the time. In any case, Washington did warn the Hawaii commanders of the imminent possibility of war, and it is unclear why a successful defense of the islands against the attack would not have been as good a casus belli as the disaster that did take place. Finally, had Hitler chosen not to declare war on the U.S. after Pearl Harbor, it might have been very difficult for Roosevelt to persuade Congress to declare war on the other, more dangerous, Axis power.

References

Czarnecki et al. (accessed 25 October 2006)

Marston (2005)

New York Times (1999-12-9; accessed 2011-4-20)

Prange (1981)

Stanton (2006)

Williford and McGovern (2003)

Zimm (2011)



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