Attack on Pearl Harbour

Attack on Pearl Harbour
Part of the Pacific Theatre of World War II
Photograph from a Japanese plane of Battleship Row at the beginning of the attack. The explosion in the centre is a torpedo strike on the USS Oklahoma. Two attacking Japanese planes can be seen: one over the USS Neosho and one over the Naval Yard.
Date December 7, 1941 Location Primarily Pearl Harbour, Hawaii Territory, United States Result Japanese major tactical victory United States declaration of war on the Empire of Japan. Germany and Italy declare war on the United States.
Belligerents
United States	Empire of Japan
Commanders and leaders
Husband Kimmel Walter Short	Chuichi Nagumo Isoroku Yamamoto
Strength
8 battleships 8 cruisers 30 destroyers 4 submarines 1 USCG Cutter 49 other ships ~390 aircraft	Mobile Unit: 6 aircraft carriers 2 battleships 2 heavy cruisers 1 light cruiser 9 destroyers 8 tankers 23 fleet submarines 5 midget submarines 414 aircraft
Casualties and losses
4 battleships sunk 3 battleships damaged 1 battleship grounded 2 other ships sunk 3 cruisers damaged 3 destroyers damaged 3 other ships damaged 188 aircraft destroyed 159 aircraft damaged 2,402 killed 1,247 wounded	4 midget submarines sunk 1 midget submarine grounded 29 aircraft destroyed 64 killed 1 captured
Civilian casualties Between 48 - 68 killed 35 wounded

Hawaiian Islands Campaign Pearl Harbour Niihau 1st Midway Johnston and Palmyra 2nd Midway K 3rd Midway

Pacific Campaigns 1940–1942 French Indochina Nauru Thailand Malaya Hawaii North America Hong Kong Philippines Guam Wake Marshalls & Gilberts Dutch East Indies New Guinea Singapore Australia Indian Ocean Doolittle Raid Solomons Coral Sea

Pacific War Central Pacific Hawaii Marshalls-Gilberts raids Doolittle Raid Coral Sea Midway RY Solomons Gilberts and Marshalls Marianas and Palau Volcano and Ryukyu Carolines Southeast Asia Indochina (1940) Thailand Dutch East Indies Malaya Burma (1941–42) Singapore Burma (1942–43) Burma (1944) Burma (1944–45) Indochina (1945) Malacca Strait Tiderace Zipper Franco-Thai War Indian Ocean (1940–45) Strategic bombing (1944–45) Southwest Pacific Philippines 1941–1942 Dutch East Indies 1941–1942 Portuguese Timor Australia New Guinea Philippines 1944–1945 Borneo 1945 North America Aleutian Islands Campaign Ellwood Estevan Point Lighthouse Fort Stevens Lookout Air Raids Fire Balloon Attacks Project Hula Japan Air raids Mariana Islands Volcano & Ryukyu Is Tokyo Starvation Naval bombardments Yokosuka Sagami Bay Kure Downfall Hiroshima & Nagasaki Kurils Japanese surrender Manchuria Manchuria (1945) Sakhalin Kuril Islands Shumshu Second Sino-Japanese War

The attack on Pearl Harbour (called Hawaii Operation or Operation AI by the Japanese Imperial General Headquarters (Operation Z in planning) and the Battle of Pearl Harbour) was a surprise military strike conducted by the Imperial Japanese Navy against the United States naval base at Pearl Harbour, Hawaii, on the morning of December 7, 1941 (December 8 in Japan). From the standpoint of the defenders, the attack commenced at 7:48 a.m. Hawaiian Time. The attack was intended as a preventive action in order to keep the U.S. Pacific Fleet from interfering with military actions the Empire of Japan was planning in Southeast Asia against overseas territories of the United Kingdom, the Netherlands, and the United States.

The base was attacked by 353 Japanese fighters, bombers and torpedo planes in two waves, launched from six aircraft carriers. All eight U.S. Navy battleships were damaged, with four being sunk. Two of these were later raised, and with the remaining four repaired, six battleships returned to service later in the war. The Japanese also sank or damaged three cruisers, three destroyers, an anti-aircraft training ship, and one minelayer. 188 U.S. aircraft were destroyed; 2,402 Americans were killed and 1,282 wounded. Important base installations such as the power station, shipyard, maintenance, and fuel and torpedo storage facilities, as well as the submarine piers and headquarters building (also home of the intelligence section) were not attacked. Japanese losses were light: 29 aircraft and five midget submarines lost, and 65 servicemen killed or wounded. One Japanese sailor was captured.

The attack came as a profound shock to the American people and led directly to the American entry into World War II in both the Pacific and European theaters. The following day (December 8), the United States declared war on Japan. Domestic support for non-interventionism, which had been strong, disappeared. Clandestine support of Britain (for example the Neutrality Patrol) was replaced by active alliance. Subsequent operations by the U.S. prompted Germany and Italy to declare war on the U.S. on December 11, which was reciprocated by the U.S. the same day.

There were numerous historical precedents for unannounced military action by Japan. However, the lack of any formal warning, particularly while negotiations were still apparently ongoing, led President Franklin D. Roosevelt to proclaim December 7, 1941, " a date which will live in infamy".

Background to conflict

Anticipating war

The attack on Pearl Harbour was intended to neutralize the U.S. Pacific Fleet, and hence protect Japan's advance into Malaya and the Dutch East Indies, where it sought access to natural resources such as oil and rubber. War between Japan and the United States had been a possibility of which each nation had been aware (and developed contingency plans for) since the 1920s, though tensions did not begin to grow seriously until Japan's 1931 invasion of Manchuria. Over the next decade, Japan continued to expand into China, leading to all-out war between those countries in 1937. Japan spent considerable effort trying to isolate China and achieve sufficient resource independence to attain victory on the mainland; the "Southern Operation" was designed to assist these efforts.

From December 1937, events such as the Japanese attack on the USS Panay and the Nanking Massacre (more than 200,000 killed in indiscriminate massacres) swung public opinion in the West sharply against Japan and increased Western fear of Japanese expansion, which prompted the United States, the United Kingdom, and France to provide loan assistance for war supply contracts to the Republic of China.

In 1940, Japan invaded French Indochina in an effort to control supplies reaching China. The United States halted shipments of airplanes, parts, machine tools, and aviation gasoline to Japan; this was perceived by Japan as an unfriendly act. The U.S. did not stop oil exports to Japan at that time in part because prevailing sentiment in Washington was that such an action would be an extreme step, given Japanese dependence on U.S. oil, and likely to be considered a provocation by Japan.

Early in 1941, President Franklin D. Roosevelt moved the Pacific Fleet to Hawaii from its previous base in San Diego and ordered a military buildup in the Philippines in the hope of discouraging Japanese aggression in the Far East. Because the Japanese high command was (mistakenly) certain any attack on Britain's Southeast Asian colonies would bring the U.S. into the war, a devastating preventive strike appeared to be the only way to avoid U.S. naval interference. An invasion of the Philippines was also considered to be necessary by Japanese war planners. The U.S. War Plan Orange had envisioned defending the Philippines with a 40,000 man elite force. This was opposed by Douglas MacArthur, who felt that he would need a force ten times that size, and was never implemented. By 1941, U.S. planners anticipated abandonment of the Philippines at the outbreak of war and orders to that effect were given in late 1941 to Admiral Thomas Hart, commander of the Asiatic Fleet.

The U.S. ceased oil exports to Japan in July 1941, following Japanese expansion into French Indochina after the fall of France, in part because of new American restrictions on domestic oil consumption. This in turn caused the Japanese to proceed with plans to take the Dutch East Indies, an oil-rich territory. The Japanese were faced with the option of either withdrawing from China and losing face or seizing and securing new sources of raw materials in the resource-rich, European-controlled colonies of South East Asia.

Preliminary planning for an attack on Pearl Harbour to protect the move into the "Southern Resource Area" (the Japanese term for the Dutch East Indies and Southeast Asia generally) had begun very early in 1941 under the auspices of Admiral Isoroku Yamamoto, then commanding Japan's Combined Fleet. He won assent to formal planning and training for an attack from the Imperial Japanese Navy General Staff only after much contention with Naval Headquarters, including a threat to resign his command. Full-scale planning was underway by early spring 1941, primarily by Captain Minoru Genda. Japanese planning staff studied the 1940 British air attack on the Italian fleet at Taranto intensively. It was of great use to them when planning their attack on U.S. naval forces in Pearl Harbour.

Over the next several months, pilots trained, equipment was adapted, and intelligence collected. Despite these preparations, the attack plan was not approved by Emperor Hirohito until November 5, after the third of four Imperial Conferences called to consider the matter. Final authorization was not given by the emperor until December 1, after a majority of Japanese leaders advised him the " Hull Note" would "destroy the fruits of the China incident, endanger Manchukuo and undermine Japanese control of Korea."

By late 1941, many observers believed that hostilities between the U.S. and Japan were imminent. A Gallup poll just before the attack on Pearl Harbor found that 52% of Americans expected war with Japan, 27% did not expect war, and 21% had no opinion. While U.S. Pacific bases and facilities had been placed on alert on multiple occasions, U.S. officials doubted Pearl Harbour would be the first target. They expected the Philippines to be attacked first. This presumption was due to the threat that the air bases throughout the country and the naval base at Manila posed to sea lanes, as well as the shipment of supplies to Japan from territory to the south. They also incorrectly believed that Japan was not capable of mounting more than one major naval operation at a time.

Objectives

The attack had several major aims. First, it intended to destroy important American fleet units, thereby preventing the Pacific Fleet from interfering with Japanese conquest of the Dutch East Indies and Malaya. Second, it was hoped to buy time for Japan to consolidate its position and increase its naval strength before shipbuilding authorized by the 1940 Vinson-Walsh Act erased any chance of victory. Finally, it was meant to deliver a severe blow to American morale, one which would discourage Americans from committing to a war extending into the western Pacific Ocean and Dutch East Indies. To maximize the effect on morale, battleships were chosen as the main targets, since they were the prestige ships of any navy at the time. The overall intention was to enable Japan to conquer Southeast Asia without interference.

Striking the Pacific Fleet at anchor in Pearl Harbour carried two distinct disadvantages: the targeted ships would be in very shallow water, so it would be relatively easy to salvage and possibly repair them; and most of the crews would survive the attack, since many would be on shore leave or would be rescued from the harbor. A further important disadvantage—this of timing, and known to the Japanese—was the absence from Pearl Harbour of all three of the U.S. Pacific Fleet's aircraft carriers ( Enterprise, Lexington, and Saratoga). Ironically, the IJN top command was so imbued with Admiral Mahan's "decisive battle" doctrine—especially that of destroying the maximum number of battleships—that, despite these concerns, Yamamoto decided to press ahead.

Japanese confidence in their ability to achieve a short, victorious war also meant other targets in the harbour, especially the navy yard, oil tank farms, and submarine base, could safely be ignored, since—by their thinking—the war would be over before the influence of these facilities would be felt.

Approach and attack

On November 26, 1941, a Japanese task force (the Striking Force) of six aircraft carriers ( Akagi, Kaga, Sōryū, Hiryū, Shōkaku, and Zuikaku) departed northern Japan en route to a position northwest of Hawaii, intending to launch its aircraft to attack Pearl Harbour. In all, 408 aircraft were intended to be used: 360 for the two attack waves, 48 on defensive combat air patrol (CAP), including nine fighters from the first wave.

The first wave was to be the primary attack, while the second wave was to finish whatever tasks remained. The first wave contained the bulk of the weapons to attack capital ships, mainly specially adapted Type 91 aerial torpedoes which were designed with an anti-roll mechanism and a rudder extension that let them operate in shallow water. The aircrews were ordered to select the highest value targets (battleships and aircraft carriers) or, if these were not present, any other high value ships (cruisers and destroyers). Dive bombers were to attack ground targets. Fighters were ordered to strafe and destroy as many parked aircraft as possible to ensure they did not get into the air to counterattack the bombers, especially in the first wave. When the fighters' fuel got low they were to refuel at the aircraft carriers and return to combat. Fighters were to serve CAP duties where needed, especially over US airfields.

Before the attack commenced, two reconnaissance aircraft launched from cruisers were sent to scout over Oahu and report on enemy fleet composition and location. Another four scout planes patrolled the area between the Japanese carrier force (the Kido Butai) and Niihau, in order to prevent the task force from being caught by a surprise counterattack.

Submarines

Fleet submarines I-16, I-18, I-20, I-22, and I-24 each embarked a Type A midget submarine for transport to the waters off Oahu. The five I-boats left Kure Naval District on November 25, 1941, coming to 10 nautical miles (19 km; 12 mi) off the harbour mouth and launched their charges at about 01:00 on December 7. At 03:42 Hawaiian Time, the minesweeper Condor spotted a midget submarine periscope southwest of the Pearl Harbour entrance buoy and alerted the destroyer Ward. The midget may have entered Pearl Harbour. However, Ward sank another midget submarine at 06:37 in the first American shots in the Pacific Theatre. A midget submarine on the north side of Ford Island missed the seaplane tender Curtiss with her first torpedo and missed the attacking destroyer Monaghan with her other one before being sunk by Monaghan at 08:43.

A third midget submarine grounded twice, once outside the harbour entrance and again on the east side of Oahu, where it was captured on December 8. Ensign Kazuo Sakamaki swam ashore and was captured, becoming the first Japanese prisoner of war. A fourth had been damaged by a depth charge attack and was abandoned by its crew before it could fire its torpedoes. A United States Naval Institute analysis of photographs from the attack, conducted in 1999, indicated a midget submarine may have successfully fired a torpedo into West Virginia. Japanese forces received a radio message from a midget submarine at 00:41 December 8 claiming damage to one or more large war vessels inside Pearl Harbour. The submarine's final disposition is unknown, but she did not return to her "mother" sub. On December 7, 2009, the Los Angeles Times reported there is circumstantial evidence three pieces of a submarine discovered 3 mi (2.6 nmi; 4.8 km) south of Pearl Harbor between 1994 and 2001 could be the missing submarine. It also reported there is strong circumstantial evidence the submarine fired two torpedoes at Battleship Row. The debris was dumped outside the harbour as part of an effort to conceal the West Loch Disaster, a 1944 ammunition explosion that destroyed six tank landing ships preparing for Operation Forager.

Japanese declaration of war

The attack took place before any formal declaration of war was made by Japan, but this was not Admiral Yamamoto's intention. He originally stipulated that the attack should not commence until thirty minutes after Japan had informed the United States that peace negotiations were at an end. The Japanese tried to uphold the conventions of war while still achieving surprise, but the attack began before the notice could be delivered. Tokyo transmitted the 5,000-word notification (commonly called the "14-Part Message") in two blocks to the Japanese Embassy in Washington, but transcribing the message took too long for the Japanese ambassador to deliver it in time. (In fact, U.S. code breakers had already deciphered and translated most of the message hours before he was scheduled to deliver it.) The final part of the "14 Part Message" is sometimes described as a declaration of war. While it neither declared war nor severed diplomatic relations, it was viewed by a number of senior U.S government and military officials as a very strong indicator that negotiations were likely to be terminated and that war might break out at any moment. A declaration of war was printed on the front page of Japan's newspapers in the evening edition of December 8, but not delivered to the U.S. government until the day after the attack.

For decades, conventional wisdom held that Japan attacked without any official warning of a break in relations only because of accidents and bumbling that delayed the delivery of a document hinting at war to Washington. In 1999, however, Takeo Iguchi, a professor of law and international relations at International Christian University in Tokyo, discovered documents that pointed to a vigorous debate inside the government over how, and indeed whether, to notify Washington of Japan's intention to break off negotiations and start a war, including a December 7 entry in the war diary saying, "our deceptive diplomacy is steadily proceeding toward success." Of this, Iguchi said, "The diary shows that the army and navy did not want to give any proper declaration of war, or indeed prior notice even of the termination of negotiations ... and they clearly prevailed."

First wave composition

The first attack wave of 183 planes was launched north of Oahu, led by Commander Mitsuo Fuchida. It included:

• 1st Group (targets: battleships and aircraft carriers)
  • 50 Nakajima B5N Kate bombers armed with 800 kg (1760 lb) armor piercing bombs, organized in four sections
  • 40 B5N bombers armed with Type 91 torpedoes, also in four sections
• 2nd Group – (targets: Ford Island and Wheeler Field)
  • 54 Aichi D3A Val dive bombers armed with 550 lb (249 kg) general purpose bombs
• 3rd Group – (targets: aircraft at Ford Island, Hickam Field, Wheeler Field, Barber’s Point, Kaneohe)
  • 45 Mitsubishi A6M Zeke fighters for air control and strafing

Six planes failed to launch due to technical difficulties.

As the first wave approached Oahu, a U.S. Army SCR-270 radar at Opana Point near the island's northern tip (a post not yet operational, but in training mode for months) detected it and called in a warning. Although it had been in use in a training mode by the U.S Army Hawaiian Department for some time, it was not fully operational. Although the operators, Privates George Elliot Jr. and Joseph Lockard, reported a target, a newly assigned officer at the thinly manned Intercept Centre, Lieutenant Kermit A. Tyler, presumed it was the scheduled arrival of six B-17 bombers. The direction from which the aircraft were coming was close (only a few degrees separated the two inbound courses), while the operators had never seen a formation as large on radar; they neglected to tell Tyler of its size, while Tyler, for security reasons, could not tell them the B-17s were due (even though it was widely known).

Several U.S. aircraft were shot down as the first wave approached land, and one at least radioed a somewhat incoherent warning. Other warnings from ships off the harbor entrance were still being processed or awaiting confirmation when the attacking planes began bombing and strafing. Nevertheless, it is not clear any warnings would have had much effect even if they had been interpreted correctly and much more promptly. The results the Japanese achieved in the Philippines were essentially the same as at Pearl Harbour, though MacArthur had almost nine hours warning that the Japanese had already attacked at Pearl.

The air portion of the attack on Pearl Harbour began at 7:48 a.m. Hawaiian Time (3:18 a.m. December 8 Japanese Standard Time, as kept by ships of the Kido Butai), with the attack on Kaneohe. A total of 353 Japanese planes in two waves reached Oahu. Slow, vulnerable torpedo bombers led the first wave, exploiting the first moments of surprise to attack the most important ships present (the battleships), while dive bombers attacked U.S. air bases across Oahu, starting with Hickam Field, the largest, and Wheeler Field, the main U.S. Army Air Force fighter base. The 171 planes in the second wave attacked the Air Corps' Bellows Field near Kaneohe on the windward side of the island, and Ford Island. The only aerial opposition came from a handful of P-36 Hawks, P-40 Warhawks and some SBD Dauntless dive bombers from the carrier USS Enterprise.

Men aboard U.S. ships awoke to the sounds of alarms, bombs exploding, and gunfire, prompting bleary-eyed men to dress as they ran to General Quarters stations. (The famous message, "Air raid Pearl Harbour. This is not drill.", was sent from the headquarters of Patrol Wing Two, the first senior Hawaiian command to respond.) The defenders were very unprepared. Ammunition lockers were locked, aircraft parked wingtip to wingtip in the open to deter sabotage, guns unmanned (none of the Navy's 5"/38s, only a quarter of its machine guns, and only four of 31 Army batteries got in action). Despite this low alert status, many American military personnel responded effectively during the battle. Ensign Joe Taussig, Jr., the only commissioned officer aboard USS Nevada, got the ship underway during the attack but lost a leg. The ship was beached in the harbour by the Senior Quartermaster. One of the destroyers, USS Aylwin, got underway with only four officers aboard, all ensigns, none with more than a year's sea duty; she operated at sea for 36 hours before her commanding officer managed to get back aboard. Captain Mervyn Bennion, commanding USS West Virginia, led his men until he was cut down by fragments from a bomb which hit USS Tennessee, moored alongside.

Second wave composition

The second wave consisted of 171 planes: 54 B5Ns, 81 D3As, and 36 A6Ms, commanded by Lieutenant-Commander Shigekazu Shimazaki. Four planes failed to launch because of technical difficulties. This wave and its targets comprised:

• 1st Group – 54 B5Ns armed with 550 lb (249 kg) and 132 lb (60 kg) general purpose bombs
  • 27 B5Ns – aircraft and hangars on Kaneohe, Ford Island, and Barbers Point
  • 27 B5Ns – hangars and aircraft on Hickam Field
• 2nd Group (targets: aircraft carriers and cruisers)
  • 81 D3As armed with 550 lb (249 kg) general purpose bombs, in four sections
• 3rd Group – (targets: aircraft at Ford Island, Hickam Field, Wheeler Field, Barber’s Point, Kaneohe)
  • 36 A6Ms for defense and strafing

The second wave was divided into three groups. One was tasked to attack Kāneʻohe, the rest Pearl Harbour proper. The separate sections arrived at the attack point almost simultaneously from several directions.

American casualties and damages

Ninety minutes after it began, the attack was over. 2,386 Americans died (48 - 68 were civilians, most killed by unexploded American anti-aircraft shells landing in civilian areas), a further 1,139 wounded. Eighteen ships were sunk or run aground, including five battleships.

Of the American fatalities, nearly half of the total (1,177) were due to the explosion of Arizona's forward magazine after it was hit by a modified 40 cm (16 in.) shell.

Already damaged by a torpedo and on fire amidships, Nevada attempted to exit the harbor. She was targeted by many Japanese bombers as she got under way and sustained more hits from 250 lb (113 kg) bombs, which started further fires. She was deliberately beached to avoid blocking the harbour entrance.

California was hit by two bombs and two torpedoes. The crew might have kept her afloat, but were ordered to abandon ship just as they were raising power for the pumps. Burning oil from Arizona and West Virginia drifted down on her, and probably made the situation look worse than it was. The disarmed target ship Utah was holed twice by torpedoes. West Virginia was hit by seven torpedoes, the seventh tearing away her rudder. Oklahoma was hit by four torpedoes, the last two above her belt armor, which caused her to capsize. Maryland was hit by two of the converted 40 cm shells, but neither caused serious damage.

Although the Japanese concentrated on battleships (the largest vessels present), they did not ignore other targets. The light cruiser Helena was torpedoed, and the concussion from the blast capsized the neighboring minelayer Oglala. Two destroyers in dry dock, Cassin and Downes were destroyed when bombs penetrated their fuel bunkers. The leaking fuel caught fire; flooding the dry dock in an effort to fight fire made the burning oil rise, and both were burned out. Cassin slipped from her keel blocks and rolled against Downes. The light cruiser Raleigh was holed by a torpedo. The light cruiser Honolulu was damaged but remained in service. The repair vessel Vestal, moored alongside Arizona, was heavily damaged and beached. The seaplane tender Curtiss was also damaged. The destroyer Shaw was badly damaged when two bombs penetrated her forward magazine.

Of the 402 American aircraft in Hawaii, 188 were destroyed and 159 damaged, 155 of them on the ground. Almost none was actually ready to take off to defend the base. Eight Army Air Corps pilots managed to get airborne during the battle and six were credited with downing at least one Japanese aircraft during the attack, 1st Lt. Lewis M. Sanders, 2nd Lt. Philip M. Rasmussen, 2nd Lt. Kenneth M. Taylor, 2nd Lt. George S. Welch, 2nd Lt. Harry W. Brown, and 2nd Lt. Gordon H. Sterling Jr. Sterling was shot down by Lt. Fujita over Kaneohe Bay and is listed as BNR (not MIA). Johhny Dains was killed by friendly fire returning from a victory over Kaawa. Of 33 PBYs in Hawaii, 24 were destroyed, and six others damaged beyond repair. (The three on patrol returned undamaged.) Friendly fire brought down some U.S. planes on top of that, including five from an inbound flight from Enterprise. Japanese attacks on barracks killed additional personnel.

Fifty-five Japanese airmen and nine submariners were killed in the action, and one was captured. Of Japan's 414 available planes, 29 were lost during the battle (nine in the first attack wave, 20 in the second), with another 74 damaged by antiaircraft fire from the ground.

Possible third wave

Several Japanese junior officers, including Mitsuo Fuchida and Minoru Genda, the chief architect of the attack, urged Nagumo to carry out a third strike in order to destroy as much of Pearl Harbour's fuel and torpedo storage, maintenance, and dry dock facilities as possible; and the captains of the other five carriers in the formation reported they were willing and ready to carry out a third strike. Military historians have suggested the destruction of these would have hampered the U.S. Pacific Fleet far more seriously than loss of its battleships. If they had been wiped out, "serious [American] operations in the Pacific would have been postponed for more than a year"; according to American Admiral Chester Nimitz, later Commander in Chief of the Pacific Fleet, "it would have prolonged the war another two years." Nagumo, however, decided to withdraw for several reasons:

• American anti-aircraft performance had improved considerably during the second strike, and two thirds of Japan's losses were incurred during the second wave. Nagumo felt if he launched a third strike, he would be risking three quarters of the Combined Fleet's strength to wipe out the remaining targets (which included the facilities) while suffering higher aircraft losses.
• The location of the American carriers remained unknown. In addition, the admiral was concerned his force was now within range of American land-based bombers. Nagumo was uncertain whether the U.S. had enough surviving planes remaining on Hawaii to launch an attack against his carriers.
• A third wave would have required substantial preparation and turnaround time, and would have meant returning planes would have had to land at night. At the time, only the (British) Royal Navy had developed night carrier techniques, so this was a substantial risk.
• Weather had deteriorated notably since the first and second wave launching, and rough seas complicated takeoff and landing for a third wave attack.
• The task force's fuel situation did not permit him to remain in waters north of Pearl Harbour much longer, since he was at the very limit of logistical support. To do so risked running unacceptably low on fuel, perhaps even having to abandon destroyers en route home.
• He believed the second strike had essentially satisfied the main objective of his mission—the neutralization of the Pacific Fleet—and did not wish to risk further losses. Moreover, it was Japanese Navy practice to prefer the conservation of strength over the total destruction of the enemy.

At a conference aboard Yamato the following morning, Yamamoto initially supported Nagumo. In retrospect, sparing the vital dockyards, maintenance shops, and oil depots meant the U.S. could respond relatively quickly to Japanese activities in the Pacific. Yamamoto later regretted Nagumo's decision to withdraw and categorically stated it had been a great mistake not to order a third strike.

Photographs

The first aerial photographs of the attack on Pearl Harbour were taken by Lee Embree, who was aboard a Boeing B-17 Flying Fortress en route from Hamilton Field, California, to the Philippines. Lee's 38th Reconnaissance Squadron had scheduled a refueling stop at Hickam Field at the time of the attack.

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  Crew members aboard Shokaku launching the attack

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  A Japanese Mitsubishi A6M2 "Zero" fighter airplane of the second wave takes off from the aircraft carrier Akagi on the morning of December 7, 1941.

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  Zeroes of the second wave preparing to take off from Shokaku for Pearl Harbour

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  A Japanese Nakajima B5N2 "Kate" torpedo bomber takes off from Shokaku.

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  Japanese Aichi D3A1 "Val" dive bombers of the second wave preparing for take off. Aircraft carrier Soryu in the background.

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  An Aichi D3A Type 99 kanbaku (dive bomber) launches from the Imperial Japanese Navy aircraft carrier Akagi to participate in the second wave during the attack on Pearl Harbour, Hawaii.

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  Battleship USS California sinking

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  Battleship USS Arizona explodes.

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  Destroyer USS Shaw exploding after her forward magazine was detonated

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  Battleship USS Nevada attempting to escape from the harbour.

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  Battleship USS West Virginia took two aerial bombs, both duds, and seven torpedo hits, one of which may have come from a midget submarine.

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  A destroyed B-17 after the attack on Hickam Field.

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  Hangar in Ford Island burns

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  Aftermath: USS West Virginia (severely damaged), USS Tennessee (damaged), and the USS Arizona (sunk).

Ships lost or damaged

Battleships

• Arizona: Exploded; total loss. 1,177 dead.
• Oklahoma: Capsized, 429 dead. Refloated November 1943; capsized and lost while under tow to the mainland May 1947
• West Virginia: two bombs, seven torpedoes, sunk; returned to service July 1944. 106 dead.
• California: two bombs, two torpedoes, sunk; returned to service January 1944. 100 dead.
• Nevada: six bombs, one torpedo, beached; returned to service October 1942. 60 dead.
• Tennessee: two bombs; returned to service February 1942. 5 dead.
• Maryland: two bombs; returned to service February 1942. 4 dead (including floatplane pilot shot down).
• Pennsylvania (Kimmel’s Flagship): in drydock with Cassin and Downes, one bomb, debris from USS Cassin; remained in service. 9 dead.

Ex-battleship (target/AA training ship)

• Utah: Capsized; total loss. 58 dead.

Cruisers

• Helena: One torpedo; returned to service January 1942. 20 dead.
• Raleigh: One torpedo; remained in service.
• Honolulu: Near miss, light damage; remained in service.

Destroyers

• Cassin: in drydock with Downes and Pennsylvania, one bomb, burned; returned to service February 1944.
• Downes: in drydock with Cassin and Pennsylvania, caught fire from Cassin, burned; returned to service November 1943.
• Shaw: Three bombs; returned to service June 1942.

Auxiliaries

• Oglala (minelayer): Damaged by torpedo hit on Helena, capsized; returned to service (as engine-repair ship) February 1944.
• Vestal (repair ship): Two bombs, blast and fire from Arizona, beached; returned to service by August 1942.
• Curtiss (seaplane tender): One bomb, one Japanese aircraft; returned to service January 1942. 19 dead.

Salvage

After a systematic search for survivors, formal salvage operations began. Captain Homer N. Wallin, Material Officer for Commander, Battle Force, U.S. Pacific Fleet, was immediately ordered to lead salvage operations. "Within a short time I was relieved of all other duties and ordered to full time work as Fleet Salvage Officer".

Around Pearl Harbour, divers from the Navy (shore and tenders), the Naval Shipyard, and civilian contractors (Pacific Bridge and others) began work on the ships that could be refloated. They patched holes, cleared debris, and pumped water out of ships. Navy divers worked inside the damaged ships. Within six months, five battleships and two cruisers were patched or refloated so they could be sent to shipyards in Pearl Harbour and on the mainland for extensive repair.

Intensive salvage operations continued for another year, a total of some 20,000 man-hours under water. Oklahoma, while successfully raised, was never repaired, and capsized while under tow to the mainland in 1947. Arizona and the target ship Utah were too heavily damaged for salvage, though much of their armament and equipment was removed and put to use aboard other vessels. Today, the two hulks remain where they were sunk, with Arizona becoming a war memorial.

Aftermath

In the wake of the attack, 15 Medals of Honour, 51 Navy Crosses, 53 Silver Stars, four Navy and Marine Corps Medals, one Distinguished Flying Cross, four Distinguished Service Crosses, one Distinguished Service Medal, and three Bronze Star Medals were awarded to the American servicemen who distinguished themselves in combat at Pearl Harbour. Additionally, a special military award, the Pearl Harbour Commemorative Medal, was later authorized for all military veterans of the attack.

The day after the attack, Roosevelt delivered his famous Infamy Speech to a Joint Session of Congress, calling for a formal declaration of war on the Empire of Japan. Congress obliged his request less than an hour later. On December 11 Germany and Italy, honoring their commitments under the Tripartite Pact, declared war on the United States. The Tripartite Pact was an earlier agreement between Germany, Italy and Japan which had the principal objective of limiting U.S. intervention in any conflicts involving the three nations. The United States Congress issued a declaration of war against Germany and Italy later that same day. Britain actually declared war on Japan nine hours before the US did, partially due to Japanese attacks on Malaya, Singapore and Hong Kong, and partially due to Winston Churchill's promise to declare war "within the hour" of a Japanese attack on the United States.

The attack was an initial shock to all the Allies in the Pacific Theatre. Further losses compounded the alarming setback. Japan attacked the Philippines hours later (because of the time difference, it was December 8 in the Philippines). Only three days after the attack on Pearl Harbour, the Prince of Wales and Repulse were sunk off the coast of Malaya, causing British Prime Minister Winston Churchill later to recollect "In all the war I never received a more direct shock. As I turned and twisted in bed the full horror of the news sank in upon me. There were no British or American capital ships in the Indian Ocean or the Pacific except the American survivors of Pearl Harbour who were hastening back to California. Over this vast expanse of waters Japan was supreme and we everywhere were weak and naked".

Throughout the war, Pearl Harbour was frequently used in American propaganda.

One further consequence of the attacks on Pearl Harbour and its aftermath (notably the Niihau Incident) was that Japanese American residents and citizens were relocated to nearby Japanese-American internment camps. Within hours of the attack, hundreds of Japanese American leaders were rounded up and brought to high-security camps such as Sand Island at the mouth of Honolulu harbour and Kilauea Military Camp on the island of Hawaii. Later, over 110,000 Japanese Americans, including United States citizens, were removed from their homes and transferred to internment camps in California, Idaho, Utah, Arizona, Wyoming, Colorado, and Arkansas.

Niihau Incident

The Japanese planners had determined that some means of rescuing fliers whose aircraft were too badly damaged to return to the carriers was required. The island of Niihau, only 30 minutes flying time from Pearl Harbour, was designated as the rescue point.

The Zero flown by Petty Officer Shigenori Nishikaichi of Hiryu was damaged in the attack on Wheeler, and he flew to the rescue point on Niihau. The aircraft was further damaged on landing. Nishikaichi was helped from the wreckage by one of the native Hawaiian inhabitants, who, aware of the tension between the United States and Japan, took the pilot's maps and other documents. The island’s residents had no telephones or radio and were completely unaware of the attack on Pearl Harbour. Nishikaichi enlisted the support of two Japanese-American residents in an attempt to recover the documents. During the ensuing struggles, Nishikaichi was killed, one collaborator committed suicide, and his wife was sent to prison.

The ease with which the local ethnic Japanese residents apparently went to the assistance of Nishikaichi was a source of concern for many, and tended to support those who believed that local Japanese could not be trusted.

Strategic implications

Admiral Hara Tadaichi summed up the Japanese result by saying, "We won a great tactical victory at Pearl Harbour and thereby lost the war." While the attack accomplished its intended objective, it turned out to be largely unnecessary. Unbeknownst to Yamamoto, who conceived the original plan, the U.S. Navy had decided as far back as 1935 to abandon 'charging' across the Pacific towards the Philippines in response to an outbreak of war (in keeping with the evolution of Plan Orange). The U.S. instead adopted " Plan Dog" in 1940, which emphasized keeping the IJN out of the eastern Pacific and away from the shipping lanes to Australia while the U.S. concentrated on defeating Nazi Germany.

Fortunately for the United States, the American aircraft carriers were untouched by the Japanese attack, otherwise the Pacific Fleet's ability to conduct offensive operations would have been crippled for a year or more (given no diversions from the Atlantic Fleet). As it was, the elimination of the battleships left the U.S. Navy with no choice but to rely on its aircraft carriers and submarines—the very weapons with which the U.S. Navy halted and eventually reversed the Japanese advance. While six of the eight battleships were repaired and returned to service, their relatively low speed limited their deployment, and they served mainly in shore bombardment roles. A major flaw of Japanese strategic thinking was a belief that the ultimate Pacific battle would be fought by battleships, in keeping with the doctrine of Captain Alfred Thayer Mahan. As a result, Yamamoto (and his successors) hoarded battleships for a "decisive battle" that never happened.

Ultimately, targets not on Genda's list, such as the submarine base and the old headquarters building, proved more important than any battleship. It was submarines that immobilized the Imperial Japanese Navy's heavy ships and brought Japan's economy to a virtual standstill by crippling the transportation of oil and raw materials: import of raw materials was down by half what it had been at the end of 1942, "to a disastrous ten million tons", while oil import "was almost completely stopped". Also, the basement of the Old Administration Building was the home of the cryptanalytic unit which contributed significantly to the Midway ambush and the Submarine Force's success.

Present day

Today, the USS Arizona Memorial on the island of Oahu honors the lives lost on the day of the attack. Visitors to the memorial reach it via boats from the naval base at Pearl Harbor. Alfred Preis is the architect responsible for the memorial's design. The structure has a sagging center and its ends strong and vigorous. It commemorates "initial defeat and ultimate victory" of all lives lost on December 7, 1941. Although December 7 is known as Pearl Harbour Day, it is not considered a federal holiday in the United States. The nation does however, continue to pay homage remembering the thousands injured and killed when attacked by the Japanese in 1941. Schools and other establishments across the country respectfully lower the American flag to half-staff.