The attack on Pearl Harbor (or Hawaii Operation, as it was called by the Imperial General Headquarters) was a surprise military strike conducted by the Japanese navy against the United States' naval base at Pearl Harbor, Hawaii on the morning of Sunday December 7, 1941, later resulting in the United States becoming militarily involved in World War II. It was intended as a preventive action to keep the U.S. Pacific Fleet from influencing the war Japan was planning to wage in Southeast Asia against Britain, the Netherlands, and the United States. The attack consisted of two aerial attack waves totaling 353 aircraft, launched from six Japanese aircraft carriers.
The attack sank four U.S. Navy battleships (two of which were raised and returned to service late in the war) and damaged four more. The Japanese also sank or damaged three cruisers, three destroyers, and one minelayer, destroyed 188 aircraft, and caused personnel losses of 2,402 killed and 1,282 wounded. 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 hit. Japanese losses were minimal, at 29 aircraft and five midget submarines, with 65 servicemen killed or wounded.
The strike was intended to neutralize the U.S. Pacific Fleet, and hence protect Japan's advance into Malaya and the Dutch East Indies, where Japan sought access to natural resources such as oil and rubber. Both the U.S. and Japan held long-standing contingency plans for war in the Pacific which were continuously updated as tensions between the two countries steadily increased during the 1930s, with the Japanese expansion into Manchuria and French Indochina greeted by steadily increased levels of embargoes and sanctions from the United States and other nations.
In 1940, under the authority granted by the Export Control Act, the U.S. halted shipments of airplanes, parts, machine tools, and aviation gasoline, perceived by Japan as an unfriendly act. The U.S. did not stop oil exports to Japan at that time in part because it was thought in Washington such an action would be an extreme step, given Japanese dependence on U.S. oil, and likely to be considered a provocation by Japan.
Following Japanese expansion into French Indochina after the fall of France, in the summer of 1941 the U.S. ceased oil exports to Japan, in part because of new American restrictions on domestic oil consumption. President Franklin D. Roosevelt had earlier moved the Pacific Fleet to Hawaii and ordered a military buildup in the Philippines, hoping to discourage Japanese aggression in the Far East. As the Japanese high command was certain that any attack on the United Kingdom's Southeast Asian colonies would bring the U.S. into the war, a preventive strike appeared to be the only way for Japan to avoid U.S. naval interference. An invasion of the Philippines was also considered to be necessary by Japanese war plans, while for the U.S. reconquest of the same had been included in War Plan Orange as far back as 1897.
While the attack accomplished its intended objective, it was completely unnecessary. Unbeknownst to Isoroku 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 War Plan Orange). The U.S. instead adopted "Plan Dog" in 1940, which emphasized keeping the Imperial Japanese Navy (IJN) out of the eastern Pacific and away from the shipping lanes to Australia while the U.S. concentrated on defeating Nazi Germany.
The attack was an important engagement of World War II. Unintentionally occurring before a formal declaration of war (which had been scheduled to be delivered shortly prior to the attack beginning), it pushed U.S. public opinion from isolationism to the acceptance participation in the war was unavoidable. The lack of warning led Roosevelt to call it "a date which will live in infamy."
War between Japan and the United States had been a possibility each nation had been aware of (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 in 1937. In 1940, Japan invaded French Indochina in both an effort to control supplies reaching China, and as a first step to improve her access to resources in Southeast Asia. This move prompted an American embargo on oil exports to Japan, which in turn caused the Japanese to initiate its planned takeover of oil production in the Dutch East Indies. Furthermore, the transfer of the U.S. Pacific Fleet from its previous base in San Diego to its new base in Pearl Harbor was seen by the Japanese military as the U.S. readying itself for a potential conflict between the two countries.
Preliminary planning for an attack on Pearl Harbor to protect the move into the "Southern Resource Area" (the Japanese term for the East Indies and Southeast Asia generally) had begun in very early 1941, under the auspices of Admiral 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. Over the next several months, pilots trained, equipment was adapted, and intelligence collected. Despite these preparations, actual approval of the attack plan was not issued by Emperor Shōwa until November 5, after the third of four Imperial Conferences 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 U.S. Pacific bases and facilities had been placed on alert on multiple occasions, with hostilities between the U.S. and Japan expected by many observers. U.S. officials doubted Pearl Harbor would be the first target in any war with Japan, instead expecting the Philippines to be attacked first due to the threat it posed to sea lanes to the south and the erroneous belief that Japan was not capable of mounting more than one major naval operation at a time.
There has been ongoing controversy due to allegations made by conspiracy theorists that some members of the Roosevelt administration had advance knowledge of the attack, and that this was purposefully ignored in order to gain public and Congressional support for the U.S. entering WWII on the side of the British Empire.
On November 26, 1941, a Japanese task force (the Kido Butai, or Striking Force) of six aircraft carriers departed northern Japan en route to a position to northwest of Hawaii, intending to launch its aircraft to attack Pearl Harbor. In all, 405 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 torpedoes. The aircrews were ordered to select the highest value targets (battleships and aircraft carriers) or, if either 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 Kido Butai and Niihau, in order to prevent the task force from being caught by a surprise counterattack.
A third midget submarine grounded twice, once outside the harbor entrance and again on the east side of Oahu, where it was captured on 8 December. Ensign Kazuo Sakamaki swam ashore from her and became the first Japanese prisoner of war. A fourth had been damaged by a depth charge attack and 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 may have successfully fired a torpedo into USS West Virginia. Japanese forces received a radio communications from a midget submarine at 00:41 8 December claiming damage to one or more large war vessels inside Pearl Harbor. That submarine's final disposition is unknown.
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, having been in training mode for months) detected them and called in a warning. Although the operators reported a target echo larger than anything they had ever seen, an untrained officer at the new and only partially activated Intercept Center, Lieutenant Kermit A. Tyler, presumed the scheduled arrival of six B-17 bombers was the source. 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 as the U.S. bombers on radar. It is also possible the operators had only seen the lead element of the incoming attack.
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 Harbor, though MacArthur had almost nine hours warning that the Japanese had already attacked at Pearl and specific orders to commence operations before they actually struck his command.
The air portion of the attack on Pearl Harbor 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 and P-40 Warhawks.
Men aboard U.S. ships awoke to the sounds of alarms, bombs exploding, and gunfire prompting bleary eyed men into dressing as they ran to General Quarters stations. (The famous message, "Air raid Pearl Harbor. 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 and only a quarter of its machine guns, and only four of 31 Army batteries got in action). Despite this and low alert status, many American military personnel responded effectively during the battle. Ensign Joe Taussig got his ship, USS Nevada, underway from dead cold during the attack. 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 four days before her commanding officer managed to get aboard. Captain Mervyn Bennion, commanding USS West Virginia (Kimmel's flagship), led his men until he was cut down by fragments from a bomb hit to USS Tennessee, moored alongside.
Gallantry was widespread. In all, 14 officers and sailors were awarded the Medal of Honor. A special military award, the Pearl Harbor Commemorative Medal, was later authorized for all military veterans of the attack.
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:
The second wave was divided into three groups. One was tasked to attack Kāneohe, the rest Pearl Harbor proper. The separate sections arrived at the attack point almost simultaneously, from several directions.
Ninety minutes after it began, the attack was over. 2,386 Americans died (55 were civilians, most killed by unexploded American anti-aircraft shells landing in civilian areas), a further 1,139 wounded. Eighteen ships were sunk, including five battleships.
Already damaged by a torpedo and on fire forward, Nevada attempted to exit the harbor. She was targeted by many Japanese bombers as she got under way, sustaining more hits from 250 lb (113 kg) bombs as she was deliberately beached to avoid blocking the harbor entrance.
USS 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 USS Utah was holed twice by torpedoes. USS West Virginia was hit by seven torpedoes, the seventh tearing away her rudder. USS Oklahoma was hit by four torpedoes, the last two above her belt armor, which caused her to capsize. USS 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 USS Helena was torpedoed, and the concussion from the blast capsized the neighboring minelayer USS Oglala. Two destroyers in dry dock 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 so the ships were burned out. The light cruiser USS Raleigh was holed by a torpedo. The light cruiser USS Honolulu was damaged but remained in service. The destroyer USS Cassin capsized, and destroyer USS Downes was heavily damaged. The repair vessel USS Vestal, moored alongside Arizona, was heavily damaged and beached. The seaplane tender USS Curtiss was also damaged. USS 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 were actually ready to take off to defend the base. Of 33 PBYs in Hawaii, 24 were destroyed, and six others damaged beyond repair. (The three on patrol returned undamaged.) Friendly fire brought down several U.S. planes on top of that, including some from an inbound flight from USS Enterprise. Japanese attacks on barracks killed additional personnel.
Fifty-five Japanese airmen and nine submariners were killed in the action. 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.
Several Japanese junior officers, including Fuchida and Genda, the chief architect of the attack, urged Nagumo to carry out a third strike in order to destroy as much of Pearl Harbor's fuel storage, maintenance, and dry dock facilities as possible. Military historians have suggested the destruction of these facilities would have crippled the U.S. Pacific Fleet far more seriously than the 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." Nagumo, however, decided to withdraw for several reasons:
At a conference aboard Yamato the following morning, Yamamoto initially supported Nagumo. In retrospect, however, 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.
Though the attack inflicted large-scale destruction, the damage was not significant in terms of American fuel storage, maintenance, and intelligence capabilities. Had Japan destroyed the American carriers, the Pacific Fleet's ability to conduct offensive operations would have been crippled for a year or so (given no diversions from the Atlantic Fleet). As it was, the elimination of the battleships left the U.S. Navy with no choice but rely on its aircraft carriers and submarines — the very weapons with which the U.S. Navy halted and eventually reversed the Japanese advance. A major flaw of Japanese strategic thinking was a belief the ultimate Pacific battle would be fought by battleships, in keeping with the doctrine of Captain Alfred 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 standstill by crippling the transportation of oil and raw materials. 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.
After a systematic search for survivors, formal salvage operations began. Captain Homer N. Wallin, Material Officer for Commander, Battle Force, U.S. Pacific Fleet, had recently been given orders to Massawa and was awaiting transportation when the Japanese attack came. In Massawa, he was to have assisted the British in clearing scuttled Italian and German ships from that harbor. Instead, Wallin was immediately retained to lead salvage operations in Pearl Harbor; Commander Edward Ellsberg was ordered to Massawa as his replacement, a switch that delayed by several months British hopes for a useful port on the Red Sea.
Around Pearl Harbor, divers from the Navy (shore and tenders), the Naval Shipyard, and civilian contractors (Pacific Bridge, and others) began work on the ships which 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 and on the mainland for extensive repair.
Intensive salvage operations continued for another year, a total of some 20,000 hours under water. Utah and Arizona 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 hulls remain where they were sunk.
U.S. Government Documents