Introduction

While this was understood only by a few people, by 1941. Japan and the United States had been on a collision course for a whole decade. Slide towards the conflict started arguably in 1902., with the signing of the Anglo-Japanese alliance between the Great Britain and Japan. But that the two countries were on a collision course only became clear in 1931., when Japan conquered Manchuria. In 1937., Japan also invaded northern China, and two years later its attention turned southwards with the conquest of island of Hainan. After it, Japan turned its attention onto Malaya, Phillipines and the Dutch East Indies. United States, by contrast, were supporting the Japan-hostile government of Chang Kai Shek, and also European colonial efforts in Asia. This was happening right at the time when Japan was repeating the parole of “Asia to Asians”. Japanese kept talking about the great eastern sphere of common progress, while they were in fact searching for the natural resources their islands did not have.

Fall of France in June 1940. gave Japan a good excuse to send troops to French Indochina, and on 27^th September it signed a Tripartite Pact with the Axis powers. As US sympathies were clearly with the Allies, President Roosevelt introduced an embargo on all key materials except for oil. Japanese called this confrontation of two powers Taihei-yono-go: “Cancer of the Pacific”. Attempting to find a diplomatic solution, Japanese government recalled a retired admiral Kichisaburo Nomura, assigning him as a Japanese ambassador to United States in January 1941. But plans were already being made for war, and the US sanctions only increased Japanese determination to fight. US ambassador to Japan, Joseph Grew, correctly predicted that Japan will “rather carry out a national harakiri than bow under foreign pressure”.

While United States government wanted to avoid war so as to have free hands to help Allies in Europe, it was clear the war was unavoidable due to actions of both sides. And Japan was heading for war. Thus, US government decided to adopt “wait-and-see” approach, avoiding any kind of preemtive strike so as to reveal the Japan as true aggressor.

Plans for the First Strike

Admiral Isoroku Yamamoto, the commander in chief of the Japanese Navy, presented a memorandum to Ministry of Navy. As war against the United States was considered inevitable, it was necessary to make the first strike that would immediately decide the war. Thus he proposed an attack on US fleet in Pearl Harbor. In mid-April, Yamamoto’s plan was accepted as a starting point for a tactical study, and a force was formed to carry out the attack – the First Air Fleet.

Three months after Yamamoto had sent his memorandum to Minister of the Navy, his plans reached the ears of the US ambassador Grew, who immediately warned the Washington. Naval Intelligence Service. Intelligence Service sent this message onto Admiral Kimmel, but added that the rumors are not to be trusted. Even so, Minister Knox wrote to the Minister of War Henry L. Stimson that the hostilities between United States and Japan could begin by a strike against the Pearl Harbor naval base. Thus it was agreed to have the forces in the base reinforced. However, it was believed that the attack will be carried out by submarines, not aircraft.

Unaware of Yamamoto’s plans, ambassador Nomura gave gis message to President Roosevelt. For his part, the President greeted that ambassador warmly, stating that there is room enough in Pacific for everybody, and invited him to meet with the Secretary of State Cordell Hull to work out an agreement. But when Japan refused a review of its policies – expansionism and alliance with Germany – United States froze all Japanese accounts in the country on 26^th of July, and six days later embargo was also expanded onto oil. In Tokyo, estimation was that without American oil, Japanese industry and economy will remain paralyzed within a year. This, and Yamamoto’s threat of resignation, influenced the Japanese government to give a go-ahead for the first strike.

Preserved documents of the Japanese High Command define the situation as follows:

1. German offensive against USSR had removed, for a time being, pressure by USSR on borders of Manchuria. Thus, while USSR is strong enough to defend itself, it is not strong enough to attack.
2. Great Britain had been pushed to defensive. It has to put everything into defense against Germany, and thus has nothing to spare for the Asia.
3. Forces fielded by the United States and her allies are not sufficient to prevent Japan from taking the Philippines, Malaya and Indonesia, nor to recover those areas in the next few months.
4. Conquest of Burma would cut off supplies to China, causing a collapse of organized resistance.
5. Due to necessity of supporting Great Britain in Europe, United States will not be capable of undertaking any offensive operations before 18 months to two years. In this time, Japan will be able to establish strong defences of the conquered areas.
6. US democracy will never accept the possibility of massive losses which would be caused by the war to reconquer lost territories, leading the US to sign a compromise peace.

Consequently, Japan refused German overtures for a joint offensive against the Soviet Union. This choice was further reinforced when Theodore Roosevelt indicated that attack on USSR would breach the peace in the Pacific (that is, United States would attack Japan). Only four days later, Japanese government assures the United States that it has no plans to attack USSR – of course, leaving unstated the fact that the reason for this was that it was planning to attack the United States instead. As preparations for the attack advanced, diplomatic activity aimed at preserving the illusion of peaceseeking was intensified. Three weks before the attack – on 17^th November 1941. – Japan sent a special emissary who officially had a task of cleaning up the diplomatic fallout caused by Japan’s actions. In reality, task was merely to sway the US into a feeling of security. Despite Cordel Hull stating in late November 1941. that Japanese-American relations are outside any diplomatic control, United States undertook no preparations for a possible Japanese attack. In Washington and London alike, prevailing opinion was that Japan will use the existing situation to easily conquer rich areas of southeastern Pacific. Japanese were also aware of this opinion, and used it to hide their real intents. Thus, Japanese preparations for invasion of the Southeastern Asia were carried out completely openly.

By contrast, preparations for the attack against Pearl Harbor were carried out in complete secrecy. The only indication that something was going on was the fact that four of the Japanese aircraft carriers had gone completely radio-silent, but this news apparently did not warrant any attention in Washington beyond withdrawing the Asiatic fleet southwards, leaving in Philippines only 27 large submarines and some destroyers.

In order for the strike to be successful, Japanese needed accurate and timely information on movements of the Pacific fleet. In this they were well-prepared: literally any Japanese presence, diplomatic, trade or similar, had Japanese agents present. Joke in the Far East was that whenever a Japanese warship enters a port, all barbers of the city in question would go to visit the captain as they were colleagues from the officer school. It was not far from the truth, either, and Japanese command was generally well informed about any movements of foreign warships in the area. In fact, Japanese command also had access to data on ship characteristics, readiness, crew quality and habits, strength and localities of air power and anti-aircraft defences, and so on. For example, arrival of Prince of Wales and Repulse to Singapore was immediately noticed. There were some failures as well: the intelligence service was not aware of large number of US submarines in the Philippines, and it reported presence of 800 aircraft on the islands when US actually only had 182 aircraft deployed there. Especially important in Japanese plans was a beauty salon Ruth, which in fact had been opened precisely to provide information to German and Japanese consulates. Most important information had been sent several days before the attack over wireless by the general consul Nagoa Kita.

On 24^th of September, Japanese Ministry of Foreign Affairs requested Japanese consulate in Honolulu to draw all ships on the spatial map of Pearl Harbour. Observations were made by Takeo Yoshikawa, who observed the fleet from a tourist aircraft flying above the Pearl. Thus, from early autumn all the way to 6^th of December, Tokyo was continuously updated on all movements of the Pacific fleet – all entrances and exits from the harbour – and thus had an accurate picture of presence of ships there.

Washington was aware of this fact, as Japanese code – codenamed Purple by the US – had been broken in summer 1940. by the system named Magic. However, Magic was not capable of reading Japanese naval codes, and thus the US were unaware of the exact movements of the Japanese fleets. US intelligence service did notice that Japanese high command is sending reports of events in Pearl Harbour to somebody, but this passed without notice and Hawaii were not warned at all. Scouting and security measures were kept at peacetime levels all the way until the attack itself.

Even those measures that had been taken proved only counterproductive. General Short, commander of the Army units on Hawaii, ordered measures against sabotage. But this meant that the port became easy target for external attack: aircraft were densely park so as to be easier to guard, soldiers were in barracks instead of on combat positions, munition was kept in storage, warships had only guards onboard, and battleships were set up like sardines in a can.

Preparations

Japanese fleet had been assembling in Kuril islands, specifically the island of Etorofu, since November. Specifically, this was the First Air Fleet under command of viceadmiral Nagumo. Place of meeting was chosen in order to keep secrecy, which was well achieved.

Yamamoto’s First Air Fleet left Japan the day after the war council. In order to preserve secrecy, Japanese command had chosen the northen route for fleet, which was somewhat risky due to bad weather but also led through areas virtually devoid of maritime traffic. For this task, aircraft carriers had received the best flight crews Japanese Navy had to offer, but they only learned of their task as necessary. Last ships arrived on 22^nd November.

Two days earlier, on 20^th of November, 20 large submarines had left the base. Of those, 11 had a seaplane each, while 5 towed a single midget submarine each instead. Majority were ordered to be in the area of Pearl Harbor starting with 7^th December. Fleet itself left the anchorage on 26^th of November in 6 AM. It consisted of six aircraft carriers, two fast battleships, three cruisers, destroyer squadron, as well as tankers and submarines. The fleet was preceded by three submarines which had left the anchorage during the night and formed a scouting screen some 200 miles ahead of the fleet. Fleet itself proceeded at cruising speed of 14 knots. It also kept track of radio traffic, including the radio stations Tokyo and Honolulu, while aircraft were carrying out scouting at distance of up to 900 kilometers away.

In order to ensure surprise, fleet elements that had been tasked with taking southeastern Asia had set out with little effort at stealth. Meanwhile the main fleet, which had remained in Japan, had released large numbers of sailors onto shore leave to mislead enemy agents. Ships in Japan also increased radio traffic, using also the calling designations of the ships which had left for the mission, thus creating impression that all ships are still in Japan.

Fleet refueled on 6^th December, and by evening of 7^th December the fleet was in a strike position 220 miles away from the Pearl Harbor without anybody having detected its presence. Tomorrow – 8^th December Tokyo time – was Sunday in Hawaii, which meant that majority of sailors will be on the shore leave. Thanks to spies in the Pearl Harbor, admiral Nagumo received continual reports on state of the fleet in Pearl Harbor, last of which arrived at 9 PM.

In Tokyo, the government was preparing the “last message to United States”, which ambassador Nomura was to give to the US government on Sunday, 7^th of December in 1 hour in the afternoon. This meant that the ultimatum would have been received by the United States at 7:30 Honolulu local time – or half an hour before the attack began. US intelligence however caught and decrypted the message, and informed Roosevelt.

The instruction to Nomura to give the message precisely at 1 PM made it clear that Japenese had prepared something for this hour, but did not know when and where. When he went to see general Marshall, he found that the general had went riding, and was to return only in 11:30. Having read the message, general agreed that the warning should be sent out, but by telegram due to danger of radio messages being eavesdropped on, so that the Japanese do not realize that the Magic had broken the Purple. As a result, Pearl Harbour received the warning only after the attack.

Japanese embassy however decyphered the telegraph too late, and so the declaration of war was only delivered in 2:20 PM. By this time, the attack had already been carried out.

Attack on the Pearl Harbour

Initial moves

Japanese fleet had just avoided running into the USS Enterprise and in 5:30 cruisers Chikuma and Tone launched their seaplanes with orders to scout the situation at Pearl Harbour. At 6:00, strike groups started taking off the carriers which had turned northwards so as to sail into the wind. Despite the de facto stormy conditions and heavy fog, well-drilled crews performed takeoff operations without incident. Aircraft were taking off at a rate of two per minute, and within 15 minutes all 189 aircraft of the first wave were in the air. Second wave of 171 aircraft would leave half an hour later, and 56 aircraft were left behind for fleet protection.

First wave was under command of commander Mitsuo Fuchida, who led the first group of 49 torpedo bombers armed with armour-piercing bombs. Also part of the first group were 40 torpedo bombers under command of corvette captain Murata, and were armed with Type 91 torpedoes. This group had as its target US battleships. Second group under command of corvette captain Takahashi consisted of 51 dive bombers with its targets being Ford Island and Wheeler Field. Third group of 43 fighters was under command of corvette captain Itai, and were tasked with air control and defense. First wave would arrive over Pearl Harbour at 8 in the morning.

Commander Fuchida used radiogoniometer to detect signals of Honolulu radio station, using those signals for navigation of his strike group.This also provided him with another, unexpected boon, as the radio station reported the exact weather conditions over the target: weather slightly cloudy, especially around the mountains, with cloud height of 3 500 feet, good visibility, and northern wind with speed of 10 miles per hour. In order to avoid increased cloud cover around the mountains, Fuchida decided to bypass the mountains and attack from the west. Once near the Pearl, Fuchida also received reports from the seaplanes. Aside from providing weather reports which differed slightly but insignificantly from those of Honolulu, they also reported presence of 10 battleships, a heavy cruiser and 10 light cruisers in Pearl Harbour – again, not completely correct but good enough for orientation. At 7:49, the attack began.

There were seveal occasions on which the Japanese nearly lost their element of surprise. At 4 AM, US mineseweeper Condor noticed a silhouette of a Japanese pocket submarine. Condor immediately notified a destroyer USS Ward of the sighting, but the submarine had slipped away. Around 6:40 AM, cargo ship Antares which had been towing a floating target signalled that he is being followed by a submarine. USS Ward noticed the submarine, and managed to sink it by a direct hit to its conning tower, before dropping a few depth charges for a good measure. But while commander reported the events, his report did not reach the base commander in time.

These were not the only midget submarines. Five such submarines were deployed for the attack, and several managed to slip into the harbour and back out, transmitting their observations to the strike force. One attempted to torpedo a seaplane carrier Curtis, but was sunk by destroyer Monaghan. Another two were also sunk, meaning that no midget submarine survived the action.

The Attack Begins

US military was not exactly blind – Hawaii in fact had a radar unit deployed. But this was a training establishment, and no attempt was made to use it for surveillance – despite the fact that no technical or practical reason existed not to. Five radar units, bought from the United Kingdom, were sent to Hawaii and deployed to warious parts of the islands. One such unit was deployed at Opana, northern mountainous area of the island of Oahu. As radar was new technology, few people understood it and even fewer believed it would work. Still, such radars could detect a ship at 50 to 80 kilometers, and an aircraft at up to 200 kilometers.

Radar usually only worked from 4 until 7 in the morning, for training purposes. In this particular morning, however, Privates Joseph Lockard and George Elliott were on the duty and kept the station operating. Thus they detected incoming Japanese aircraft, but upon informing their superior, they were told that the readings are most likely a glitch in the equipment. Thus, nobody in position received any warning before the bombs started falling.

Japanese aircraft bypassed the foggy hills of Oahu. Japanese plan had two variants. First one, if complete suprise had been achieved, was for torpedo bombers to carry out the initial strike, using the peace to get as close to battleships as possible before dropping torpedoes. This would be followed by level bombing, and finally by strikes by dive bombers, aimed against now alterted air bases and anti-aircraft defences. If surprise failed, second variant would be used. In this case, first attack would be carried out by dive bombers, to draw enemy attention. After this, level bombers would suppress anti-aircraft defense positions. Finally, torpedo bombers would use the confusion to carry out attack on the battleships. Choice of the manner of the attack would be carried out by the commander according to the situation. But a mistake was made in choice of the signal. Commander would signal his decision by firing rockets, but instead of using signal rockets of different colours, white rockets were used. One rocket would signal first mode of the attack, two rockets the second mode.

Having not received any warnings, commander Fuchida realized that the surprise had been achieved. Thus, at 7:40, he fired a signal rocket. Dive bomber and torpedo bomber squadrons responded immediately, climbing and diving to their respective approach altitudes, but the fighter squadron continued to fly in a straight line. Concluding that the fighters had not seen the signal, Fuchida fired another rocket. This time, fighters responded promptly and took up their assigned position. But the second rocket caused confusion, as commander of dive bombers, Kakuichi Takahashi, concluded that Fuchida had noticed at the last moment that Americans are ready for defense. Consequently, he immediately led his squadron into attack. Squadron itself split into two groups, with first group attacking Ford Island and Hickam Field aerodromes, and the second group attacking Wheeler Field aerodrome. It was basically bombing fish in a barrel – aircraft were lined up very tightly out in the open, with no attempts made to either protect them from air attacks or even just camouflage them.

This caused some confusion for the torpedo bombers, which were supposed to pass over the airfields and thus confuse the Americans who would take them for their own aircraft. Having to avoid the flame and smoke, Murata took his squadron straight towards the battleships, coming from the west. While this was a less favourable position for the attack, it meant that first torpedoes were dropped merely two minutes after the dive bombers had started their own attack. Level bombers under Fuchida’s direct command remained at altitude of 2000 meters, allowing for a good overview of the events on the ground. He radioed a message “Tora, tora, tora” which reported a complete success of the surprise attack to the battleship Nagato. Soon after, at 8:05, Japanese level bombers also dropped their bombs on the battleships.

Wakeup Call

US armed forces were rather surprised by the attack on Pearl Harbour. Too much faith was placed into distance: Hawaii were 6000 kilometers from Yokohama and 4000 kilometers from Marshall Islands. And the attack itself was planned and executed to the highest standards. As a result, none of the 96 ships in the harbour were on alert, and were only lightly crewed due to day being Sunday. Airplane activity was normal there, so alert was raised only once the bombs started falling.

Main target were the Pacific Fleet battleships, anchored in a “Battleship Row”. These were the battleships California, Maryland, Oklahoma, Tennessee, West Virginia, Arizona and Nevada. Arriving in low-altitude flight, torpedo bombers carried out their attack before anyone could react. Dropping torpedoes in a shallow bay, whose depth was no more than 13 – 14 meters, was thought impossible, but the Japanese did it. Twenty-four out of forty torpedo planes attacked the battleships. California, Oklahoma and West Virginia were hit heavily by first two waves, and Nevada also in the second. In total, Oklahoma and West Virginia were struck by nine torpedoes each (though number for West Virginia is uncertain – 4, 5, 6, 9?), while two hit California and one hit Nevada. Last group of torpedo planes shifted their attacks on other targets. Six torpedoes struck Utah, a battleship that had been converted to a target for naval gunnery, but had been confused for an active battleship by Japanese pilots. Another five torpedoes struck cruiser Helena and minelayer Oglala.

But three battleships in the second row were shielded by the hulls of their comrades in the first row. The last attack was carried out by the 50 horizontal bombers under command of Fuchida himself. Damage again was heavy, with two heats each on California, Maryland and Tennessee and a few on West Virginia. But the main victim was Arizona, which had been struck many times. One of these hits penetrated in the vicinity of her forward magazines, which detonated, destroying the ship. Nevada, which had managed to get underway during the last part of the attack, was hit repeatedly by dive bomber attacks and had to be run ashore.

Despite the fact that 96 warships had been present, the first wave had barely had any losses thanks to catching the enemy unprepared. But this did not last long. Battleships were first to respond, and soon anti-aircraft guns started replying to the attack. Out of the battleships themselves, it was Nevada who opened fire first. There, a captain of the corvette had taken command, and Nevada was ready to fight when the second wave came. As a result, ship received only one torpedo in the bow, having shot down several torpedo planes. But the ship came under attack by bombers soon after, and as already noted, received several hits by bombs. Remorkers had to be called in, and helped the battleship to beach itself in shallow water.

Most powerful battleship of the Pacific fleet, West Virginia, had received six (?) torpedo hits, and there was major danger of the ship rolling over due to assymetric flooding. Quick counterflooding helped alleviate this danger, and after receiving several bomb hits, the ship settled in shallow water. Worst hit was Oklahoma, which had lost basically the entire side to torpedo hits and consequently rolled over. Ship settled at 150° angle when its masts hit the muddy seabed, leaving some 400 men of its crew trapped in a steel grave. Eventually, 32 men were saved by cutting through the hull, but many more remained trapped. Overview after the ship had been raised showed that one managed to survive for 18 days.

Arizona had been protected from torpedo hits by repair ship Vestal, and so received attention of the bombers. It ended up being hit by four bombs of over 1 000 kilograms. One of the bombs either passed straight down the funnel, or else pierced the armour deck close to one of main gun turrets. Whatever the case, main gun magazines were eventually set ablaze. While battleships do have ways to flood the magazines, water reliease walves were locked down so that it wouldn’t be done by accident or stupidity. Before keys could be found, the magazines detonated, killing 1100 men out of 1500 man-crew, and splitting the ship in half.

California had received two torpedo hits almost immediately, and had started listing. Torpedoes had also damaged and set fire to fuel oil tanks, enveloping the ship into thick black smoke. Hits had also knocked out electricity generators. But the most lethal damage proved to be a lack of authority figure: ship which could have been saved was abandoned before time, and after three days settled onto the seabed.

And things could have quickly become far worse. Just nearby the battleship row was an oil tanker Neosho. It was full of oil, and to make matters worse, its berth was right next to the shoreside oil tanks. Realizing the danger of being hit due to proximity to the battleships, as well as potential consequences of such a hit and resultant fire, captain cut the lines and sailed off. Neosho soon came under attack by a Japanese dive bomber. Despite very light anti-aircraft armament, Neosho managed to shoot down the plane and leave the harbour.

By 8:30, after half an hour, the first wave had passed. Japanese had lost only 3 fighters, 1 dive bomber and 5 torpedo bombers. But at 8:55, engine noise signalled the arrival of the second wave, led by a Lieutenant Commander Shigekazu Shimazaki. His task was to destroy any targets missed by the first wave. Because of this, as well as the expectation of much stronger resistance, makeup of the second wave was significantly different. It had 171 aircraft, of which 81 were dive bombers tasked with attacking surviving ships in the harbour. With them were 54 level bombers tasked with attacking Hickam Field and Keniohi air fields, with 36 fighters to provide air cover. Lieutenant Commander Takashige Egusa, leading dive bombers, ordered his pilots to concentrate their attacks against ships which put up the most intense anti-aircraft fire, as these will have been the ones least damaged in the first attack.

This time, the attack was not so easy. Japanese lost 14 dive bombers and 6 fighters, but American losses were again much heavier. Battleship Tennessee, which was protected from torpedoes by the neighbouring West Virginia, was hit several times, but the fires were quickly put out as the crews were now ready. Even luckier was Maryland, which had been shielded from torpedoes by Oklahoma and now received only one bomb, allowing it to return to service in as few as eight weeks.

Japanese aircraft also attacked Pennsylvania, which was undergoing repairs in a drydock, together with two destroyers. Pennsylvania suffered minor damage, but destroyer Cassin was victimized by a bomb, with explosion piercing fuel lines and setting fuel on fire. This in turn led to a munitions explosion which blew off destroyer’s side, throwing it onto destroyer Downes which was also in the drydock, right beside it. Three bombs hit destroyer Shaw, causing a munitions explosion, but this destroyer was also in a drydock and thus failed to actually sink.

Aftermath

Japanese left at around 9:45, leaving behind chaos. Oil fires from oil on ships and spills which had also caught fire produced thick black smoke, and many sailors died in fires. Damage was extremely heavy – no battleship was ready for action. Arizona was a total loss, another four battleships were partly or completely flooded and had settled onto the seabed, and remaining three battleships were heavily damaged but still afloat. Also destroyed were a minelayer, old battleship-turned-target-ship, two destroyers and a large floating dock. Heavy damage was done to three cruisers, a seaplane carrier and a workshop ship. Aircraft losses were also heavy, with 188 aircraft having been destroyed on the ground. Human losses were heavy, with 2 403 dead and 1 178 wounded.

By comparison, Japanese losses had been minor. They had lost 29 aircraft, 5 pocket submarines and 50 men. Strict obedience to the primary task meant that the attack was almost entirely focused on battleships, while other damage was caused mostly by accident. This meant that oil tanks and shoreside workshops had remained completely undamaged, allowing surviving units of the Pacific fleet to use Pearl Harbour as a base of operations.

Fuchida and other officers wanted to carry out a third attack, as many important objects had remained undamaged. Admiral Nagumo, however, refused, believing that a new attack would not increase American losses enough to justify increased losses that Japanese aircrews would incur in such an attack against now prepared enemy. He also believed that US had at least 50 operational bombers, and also had no information about location of American aircraft carrier groups and submarines. Thus, he decided to retreat away from the reach of US land-based and carrier aircraft.

Americans meanwhile undertook quick countermeasures. Hawaii command ordered troops into defensive positions against a potential repeated attack or even an amphibious assault. Admiral Halsey, commander of the Enterprise battlegroup, immediately sent aircraft to scout out area to the west of the Hawaii – of course, finding nothing as the Japanese fleet was to the north.

Admiral Kimmel sent a message to the Lexington battlegroup, directing it to intercept and destroy the enemy on Pearl Harbour – Jaluit line. Enterprise also overheard the message, and Halsey sent another group of aircraft. But this message merely sent US carriers racing southwards, away from the Japanese squadron. This was done despite the fact that Japanese aircraft had been flying northwards after the attack. In fact, one radar station on Oahu had tracked the flight path of Japanese aircraft for full 200 kilometers, but its report reached Admiral Kimmel only 48 hours later…

Message from Pearl Harbour was caught by the radio-service in Washington. Admiral Stark was immediately alerted, who then alerted minister Knox, who in turn alerted President Roosevelt at 13:47. At 14:28, Admiral Stark was able to inform the President that the fleet’s losses were heavy and there were many casualties. President Roosevelt dictated a communique for the press, and called a conference for 15 hours. Present were ministers Stimpson, Hull and Knox, as well as general Marshall and admiral Stark. Measures were taken, with all bases in the Pacific preparing measures against sabotage, as well as securing the Panama Canal and Alaska. Military reinforcements were also sent to states of Latin America, and Army units reinforced the Western Coast. In six weeks, 600 000 troops had taken up defensive positions.

But it was clear that the main threat was to military bases in the Pacific. Therefore, reinforcements were dispatched almost immediately. This was a highly dangerous endeavour, as Japanese fleet dispositions were unknown, and thus transit of troops to faraway bases was coupled with significant risk of destruction by air or naval attack. But Japanese command proved incredibly strategically incompetent – they failed to do anything to attack these reinforcements. There were no air patrols, naval patrols, and not a single submarine had been sent to block the ports and likely transit routes. Instead, Japanese were wholly concentrated on conquests in Southeastern Asia.

US Navy, unaware of this, counted with a possibility of Japanese attack against the convoys. Therefore two convoys were organized in San Francisco, comprised of only very fast ships. Within ten days, these convoys transported reinforcements to Pearl Harbour.

At time of the attack on Pearl Harbor, two transport ships carrying 4 500 soldiers were travelling from Hawaii to Phillippines, under strict orders of radio silence. As they were now travelling through extremely dangerous area, they were redirected, and after 15 days safely arrived to Australia. Reinforcements kept being dispatched, and by June 1942., US Army had 150 000 troops in the area. Speed and thoroughness of the response will have major impact on further events.

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