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Chapter 2:
The Japanese Attack on Pearl Harbor,
Planning and Execution


The Japanese attack on the United States Fleet at Pearl Harbor on 7 December 1941 has been the subject of so much writing and debate that general familiarity with the important events surrounding that fateful episode is assumed. Consequently no attempt is made herein to present the entire story or to analyze the political and military effects which the attack had on the subsequent course of the war. This is rather a presentation of material not hitherto available, dealing specifically with the operational aspects of the planning and execution of the attack.

The information contained in this narrative was supplied from memory by the Japanese officers listed below and, although considered accurate in general, may be subject to minor corrections in detail after examination of translated documents.


The purposes of the surprise attack on Pearl Harbor were:

To render impotent the United States Pacific Fleet in order to gain time and to insure freedom of action in the South Seas Operation, (including invasion of the Philippine Islands), and to facilitate the defense of the mandated islands. The attack was conceived and proposed by Admiral Isoroku Yamamoto, CinC of the Japanese Combined Fleet. In January 1941, Rear Admiral Tokijiro Onishi, Chief of Staff of the 11th Air Fleet was ordered to make a preliminary study of the operation, and in the first part of September 1941 members of the Operations Section of the Naval General Staff and selected members of the Staffs of the Combined Fleet and the First Air Fleet commenced work on the details of the actual plan.

Organization of the Task Force

In order to avoid detection it was necessary to keep the force as small as possible and at the same time to provide the most powerful air attack force available. This was effected by reinforcing the air groups


of Carrier Division 1 (Akagi, Kaga) and Carrier Division 2 (Soryu, Hiryu) with the highly trained pilots of Carrier Division 4 (Ryujo, Ryuho). In addition the recently organized Carrier Division 5 (Zuikaku, Shokaku), was similarly reinforced with such highly trained flight personnel as were available and special training was scheduled to bring this division to the peak of efficiency. The surface force was composed of vessels selected for long cruising range, and the commanding officers of all units were the best available. For the complete organization see Appendix I.

Selection of Track

Three courses were considered for the Pearl Harbor Task Force:

  1. The northern course which was actually used. Appendix 2.)

  2. A central course which headed east, then following along the Hawaiian Archipelago, and

  3. A southern route passing through the Marshall Islands and approaching from the south.

The principle disadvantage of the northern route was the possibility of adverse weather which would further complicate the difficult problem of refueling at sea. However this was outweighed by the fact that the northern route involved little chance of meeting commercial vessels and offered the best hope of avoiding detection by United States Navy land-based search planes, thus greatly increasing the chances for surprise. The central and southern routes offered advantages and disadvantages generally the opposite of the northern route; although the calmer sea would facilitate refueling, the chances of being discovered by patrol planes were great because the routes passed near Wake, Midway, Palmyra, and Johnston Islands. The element of surprise and the ability to refuel at sea were the most important factors and if either failed, the operation would have been impossible. Since it was considered that the refueling problem could be overcome by training, the northern route was selected. In order to prevent discovery enroute, it was planned to:

  1. Pass between Midway and the Aleutian Islands outside the range of patrol planes.

  2. Use screening destroyers ahead of the compact main body, and in the event any vessels were encountered, divert the main body to avoid detection.

  3. Use three submarines to patrol ahead and give warning.

  4. Maintain complete radio silence.

Selection of Date and Time of Attack

In view of the phase of the moon, 10 December would have been most suitable from a tactical standpoint since the darkness would facilitate surprise. However, because of the general international situation and the possible advantages to be derived from a Sunday attack, the Imperial Headquarters, in cooperation with the Commander in Chief of the Combined Fleet, designated 8 December (east longitude date) as "X"-day. In order to provide maximum daylight fo the operation the take-off time was set as near dawn as possible and the attack time was set at 0330 Japanese time (0800 Hawaiian time). Sunrise was 0230 Japanese time (0700 Hawaiian time)

The Attack Plans

Since the primary objective of the attack was to put the United States Pacific Fleet temporarily out of action, the main force of the attack was to be directed at battleships and carriers. It was decided that torpedo attack was the most effective method of putting these major warships out of commission for a considerable length of time. Hence the following two difficulties had to be considered:

  1. Pearl Harbor is narrow and shallow.

  2. Pearl Harbor in all probability would be equipped with torpedo nets.

To overcome the first difficulty it was planned to attach special stabilizers to the torpedoes and to launched them from an extremely low altitude, thus preventing them from diving. In regard to the second


difficulty, since torpedo nets would prevent a successful attack with torpedoes, provision was also made for horizontal and dive-bombing. In addition it was planned to use fighter aircraft to destroy American aircraft in order to prevent a counterattack on the main Japanese attack units or an attack by American bombers against the task force itself. At the beginning of the attack the fighter striking units were to maintain a single formation and patrol over Oahu, attacking American fighters as they got into the air. If no American aircraft took off, the fighters were to split up and attack grounded aircraft.

On 3 November, Admiral Nagano, Chief of the Naval General Staff, in cooperation with Admiral Yamamoto, definitely decided to attack Pearl Harbor if diplomatic negotiations with the United States failed. On 1 December 1941, Admiral Yamamoto finally approved the general plan as outlined above. By this time the following individuals were cognizant of the complete plan:

The Emperor knew of the plan to attack the main strength of the United States Pacific Fleet with a carrier task force after the last ultimatum to the United States Government had been delivered.

No persons not connected with the Navy were familiar with the plan.

Preparations for the Operation

In August 1941 intensive training of the designated air groups was commenced. Emphasis was placed on shallow water torpedo drops, on horizontal and dive bombing, and on strafing tactics. Surface vessels conducted many refueling exercises and by the end of November the Task Force was considered to be satisfactorily trained.

Orders Placing Plan Into Effect

In the period from early November 1941 to 2 December 1941 the Chief of the Naval General Staff issued a series of general orders regarding the Pearl Harbor attack to the Commander in Chief of the Combined Fleet who in turn issued more specific orders to the Pearl Harbor Attack Force (First Air Fleet). (See Appendix 14).

Movement of Pearl Harbor Task Force

In accordance with instructions from CinC Combined Fleet, the Task Force sortied from Hitokappu bay at 0600, 26 November and proceeded along the track shown in Appendix 2. On 2 December instructions were received to the effect that negotiations had failed and that 8 December was designated as "X"-day. The refueling was successfully completed on 3 December without mishap. (In the event of failure of the fueling operation it had planned to continue without the destroyers.) After refueling, the Task Force proceeded along the track without incident. No shipping was encountered and the force successfully escaped detection. During the approach, the following instructions were in effect:

  1. If discovered prior to "X"-minus-2-day, the Task Force was to return to Japan without executing the attack.

  2. If discovered prior to "X"-1-day, the decision as to what action to take was the responsibility of the Task Force Commander.


  1. If discovered on "X"-minus-1-day or the morning of "S"-day the Task Force was to continue with the attack.

  2. If at any time during the approach to Pearl Harbor the negotiations with the United States had been successful the attack would have been cancelled.

  3. If, at any time during the approach to Pearl Harbor the American Fleet attempted to intercept the Japanese Task Force, the Japanese planned to counterattack. If the American Fleet advanced into Japanese home waters in pursuit of the Task Force it was planned to commit the Main Body of the Japanese Fleet as a support force.

    If, after arriving in Hawaiian waters, it was found that the American Fleet was at sea and not in Pearl Harbor, the Japanese planned to scout a 30-miles radius around Oahu and attack if contact was made; otherwise they were to withdraw.

During the approach the main force in the Inland Sea and land-based air units in the Kyushu area carried on deceptive communications designed to indicate that the Task Force was still in Japanese waters. The Task Force arrived at the launching point 200 miles north of Oahu at 0730, 7 December (Hawaiian time).

The Attack

The air attack was executed by two waves of aircraft composed of 3 groups each. The organization, plane assignment, armament and targets assigned are shown in Appendix 3. In addition there was a combat air patrol as shown in Appendix 4 and also reconnaissance flights by ship-based seaplanes as listed below:

Type Aircraft Number of
Ship Mission
Type Zero recco seaplane 2 Tone (1)
Chikuma (1)
Reconnaissance of Pearl Harbor and Lahaina anchorage just before attack
Type 91 recco seaplane 4 Hiei (1)
Chikuma (1)
Patrol waters around Oahu during attack.

The organization of the attack units was based on the following considerations (See Appendix 3).

First Attack.

  1. Horizontal Bombing Unit (50 Type 97 Carrier Attack Planes)
    Target : Battleships

    1. It was presumed that the American battleships could be effectively crippled by 800-kg armor piercing bombs, dropped from an altitude of 3,000 meters or more.

    2. Horizontal bombing is relatively inaccurate. However, it was estimated, considering the degree of training of the bombing units, that four out of five salvos could be placed on stationary battleships if a formation of five airplanes were employed from an altitude of 3,000 meters or more. Therefore it was concluded that about four battleships could be effectively crippled with 10 formations of type 97 bombers.

    3. Because of the accuracy of torpedo attacks, it was desired to use as many torpedoes as possible. However both bombing attacks and torpedo attacks were used for the following reasons:

      1. If torpedo nets were laid, the torpedo attacks would be unsuccessful.


      1. Launching torpedoes in shallow water such as that at Pearl Harbor required special technique.

      2. Ordinarily, ships were moored in pairs breast each other. Consequently, bombing attacks were the only effective method against the inside ships.

  1. Torpedo Unit (40 Type 97 Carrier Attack Planes)
    Target: Battleships and Aircraft Carriers

    1. Short range torpedo runs are very accurate. Therefore the pilots most skillful at shallow water torpedo drops were selected in order to put as many battleships and carriers temporarily out of action due to underwater damage as the conditions mentioned would permit. (Because the carriers were not at their anchorages on the day of the attack, the planes concentrated on the battleships).

  2. Dive Bombing Unit (54 Type 99 Carrier Bombers)
    Target: Air Bases Considerations:

    1. Since the primary objective of the attack on Pearl Harbor was to put the United States Pacific Fleet temporarily out of action, the primary targets were battleships and carriers. However fighter plane bases were to be attacked first because it was necessary to prevent a counterattack by American fighter planes against the horizontal bombing and torpedo units.

    2. It was known that Wheeler Field was a United States Army fighter plane base and that carrier planes from the United States Pacific Fleet were usually kept at Ford Island.

  3. Fighter Striking Unit (45 Type Zero Carrier Fighters)
    Targets: Airborne planes, grounded planes. Considerations:

    1. At the beginning of the attack the fighter striking unit was to maintain a single formation and patrol over Oahu, attacking any enemy fighter planes which got into the air.

    2. If no fighter opposition was met in the air, the unit was to split up as indicated above and attack grounded airplanes on the various airfields on Oahu, thereby preventing a counterattack against the Task Force.

Second Attack.

  1. Horizontal Bombing Unit (54 Type 97 Carrier Attack Planes)
    Target: Air Bases Considerations:

    1. By putting the American airplanes on Oahu temporarily out of action, counterattack against the Task Force could be prevented.

  2. Dive Bombing Unit (81 Type 99 Carrier Bombers)
    Target: Aircraft Carriers and Cruisers.



    1. Although the 250-kg. bombs which the airplanes were able to carry could not pierce the armor of the battleships, it was estimated that they would be effective against United States cruisers and carriers.

    2. It was estimated that there were then four or five American carriers operating in the Hawaiian Area. They were the targets of this dive bombing unit. (Since the aircraft carriers were not at their anchorages on the day of the attack, most of the blows were directed against battleships).

  1. Fighter Striking Unit (36 Type Zero Fighters)
    Target: Airborne airplanes, grounded airplanes Considerations:

    1. By destroying enemy aircraft counterattacks against air units and the surface forces would be prevented.

Execution of Attack

The aircraft in the first attack units took off at 0600 (Hawaiian Time) from a position 200 miles north of Oahu. The second attack unit took off one hour and fifteen minutes later. The tracks of the attacking aircraft after they sighted Oahu are shown in Appendix 5. The approach was made at an altitude of 3,000 meters above a dense cloud layer which was hanging about 2,000 meters. The first group arrived over Oahu at about 0740, were ordered to attack at 0750 and attacked as follows:

Unit   Target   Time
Dive Bombing Unit   Wheeler Field   0755
Torpedo Attack Unit   Battleships   0757
Fighter Striking Unit   Grounded Aircraft   0800
Horizontal Bombing Unit   Battleships   0805

The Second Attack Unit sighted Oahu at 0840, was ordered to attack at 0855 and commenced the attack about 0900. Complete details are not available since the Commanding Officer, Lieutenant Commander Shimazaki was killed in action January 1945. Both attack units attacked for 30 to 60 minutes and then rendezvoused with their respective fighter units at a point bearing 340° distance 20 miles from Kaena Point and proceeded directly back to the carriers. Because of the length of the flight, it was impossible to withdraw on deceptive courses.



The estimated damage to the American Forces was as follows:

  Naval Vessels  
Sunk Heavily Damaged Lightly Damaged
4 battleships
1 cruiser
2 tankers
4 battleships 1 battleship
Shot down 10
Destroyed on ground 250
(Undetermined number destroyed in hangars)

The above estimate was made after a study of pilot reports and photographs taken by attacking aircraft. No reconnaissance planes were used to assess the damage immediately after the attack but one element of fighter aircraft was ordered to fly as low as possible and observe results after the attack was completed.

Japanese Submarines

About 10 to 12 "I" type submarines of the Advance Expeditionary Fleet participated in the Pearl Harbor attack. These submarines departed Yokosuka Naval Base on 11 November and proceeded toward Pearl Harbor by different routes. The I-19, I-21 and I-23 proceeded ahead of the Task Force to act as lookouts. The remaining submarines, which included the I-69, I-74 and I-75 rendezvoused at Kwajalein and then proceeded to Hawaii. Five of the latter group carried midget submarines (two-man crew) on the deck aft of the conning tower. The submarines were given the following orders:

  1. Establish lookout stations in Hawaiian waters not later than the evening of 6 December (Hawaiian time). Launch midget submarines when on station..

  2. Scout and reconnoitre Hawaiian area prior to the attack. Midget submarines will enter Pearl Harbor and attack the American Fleet after the air attack.

  3. Attack before initiation of the Task Force strike is strictly forbidden.

The use of the midget submarine was an experiment but it was thought that they would be of some assistance to the Task Force and also possibly make effective torpedo attacks themselves. One midget submarine reported the results of the Air Attack as observed on the night of 7 December and at 0041 hours 8 December another message was received from a midget submarine claiming damage to one or more large war vessels inside Pearl Harbor. This attack was partially verified by a large submarine patrolling outside the harbor which witnessed a great explosion at 2101, 7 December. However, since none of the five midget submarines was recovered, their exact story was never known.

One of the "I" class submarines was lost; the time and place of sinking was unknown to the Japanese. In addition one submarine was detected and depth charged near the entrance to Pearl Harbor. Although it ran afoul of the submarine net, it extricated itself and returned to its base in a damaged condition. The remaining submarines operated in the vicinity of Hawaii until early January, and then proceeded to the West Coast of the United States.


General Information

  1. The attacks on Pearl Harbor were not continued or followed up by surface craft bombardment because the sole objective of the attack was to destroy the capital ship strength of the United States Pacific Fleet in order to delay any United States advance across the Pacific. Hence, since this objective was achieved by air attack, no further attack was considered necessary. Also, since the whereabouts of the American carriers was unknown and the chances of locating them by air search were small, it was considered that a quick withdrawal would be most advantageous. Consideration was also given to the probability of a counterattack by the estimated 50 or more large land-based planes that remained in Hawaii after the attack.

  2. No landing operation was planned because insufficient time was available to make all preparations during the month of November and also it was recognized that the problems of ship speed and logistics would have made it impossible to execute the initial attack without detection during the approach.

  3. During the Pearl Harbor Operation the following units were diverted to secondary targets:

    1. The Midway Neutralization Unit (Akebono, Ushio) left Tokyo Bay about 1 December, arriving at Midway during the night of 7 December, bombarded the air base and returned to the western part of the Inland Sea.

    2. It had been planned to conduct an attack on Midway while returning to Japan but the operation was canceled because of weather. On 16 December however, while proceeding to Japan from Pearl Harbor, two aircraft carriers (Soryu and Hiryu), two cruisers (Tone, Chikuma), and two destroyers (Tanikaze, Urakaze) were diverted to Wake Island to assist the invasion on 23 December.

  4. During the planning and execution of the Pearl Harbor attack the following sources of intelligence were utilized:

    1. Interrogation of crews of merchant ships which called at Hawaii in mid-November.

    2. Submarines on reconnaissance duty in Hawaiian waters immediately preceding outbreak of the war.

    3. Commercial radio broadcasts from Hawaii.


Appendix 1

TASK FORCE Air Attack Force CINC
1st Air Fleet,
Vice Adm Nagumo,
Under Direct Commander Six Aircraft Carriers
Akagi   Zuikaku
Kaga    Hiryu
Soryu Shokaku
Air Attack
Screening Unit Comm Des Ron 1
Rear Adm Omori, Sentaro
One Light Cruiser
Nine Destroyers
Urakaze   Kasumi
Isokaze   Arare
Tanikaze   Kagero
Hamakaze   Shiranuhi
Screen Cover
Support Force Com Bat Div 3
Rear Adm Mikawa, Gunichi
Two Battleships
Hiei   Kirishima
Two Heavy Cruisers
Tone   Chikuma
Screen Support
Patrol Unit Com Sub Div 2
Capt. Imaizumi, Kijiro
Three Submarines
Patrol Ship Lanes
Midway Neutralization Unit Comm Des Div 7
Capt Konishi, Kaname
Two Destroyers
Akebono   Ushio
Attack Air Base on Midway
  1 Supply Unit Captain of Kyokuto Maru
(Special Duty Ship)
Captain of Kyokuto Maru Five Tankers
Kenyo Maru
Kyokuto Maru
Kokuyo Maru
Shinkoku Maru
Akebono Maru
  2 Supply Unit Captain of Toho Maru Three Tankers
Toho Maru
Toei Maru
Nippon Maru
Note: These answers are based on recollections and inquiries of Comdr Fuchida, Mitsuo,
Commander of the Akagi Air Unit.


Appendix 2



First Attack Unit 1 Group 1 Attack Unit Comdr Fuchida Comdr Fuchida Type 99 Carrier Bomber 15 50 189 360 Horizontal Bombing Attack One 800-kg. Armor-Piercing Bomb Battleships
2 Attack Unit Lt. Comdr. Hashiguchi 15
3 Attack Unit Lt. Abe 10
4 Attack Unit Lt. Comdr. Kusumi 10
1 Special Attack Unit Lt. Comdr. Murata 12 40 Torpedo Attack One 800-kg. Aerial Torpedo Battleships
2 Special Attack Unit Lt. Kitajima 12
3 Special Attack Unit Lt. Nagai 8
4 Special Attack Unit Lt. Matsumura 8
2 Group 15 Attack Unit Lt. Comdr. Takahashi Type 99 Carrier Bomber 27 54 Dive Bombing Attack 250-kg. Land Bomb Air Bases Ford Island Wheeler
16 Attack Unit Lt. Sakamoto 27
3 Group 1 Fighter STriking Unit Lt. Comdr. Itaya Type Zero Carrier Fighter 9 45 Air Control and Strafing Attack Two 20mm MGs Two 7.7mm MGs 1. Airborne airplanes
2. Strafing of grounded planes. Ford Island Hickam Wheeler Ewa Kaneohe
2 Fighter Striking Unit Lt. Shiga 9
3 Fighter Striking Unit Lt. Suganami 9
4 Fighter Striking Unit Lt. Okajima 6
5 Fighter Striking Unit Lt. Kaneko 6
6 Fighter Striking Unit Lt. Sato 6
Second Attack Group 1 Group 6 Attack Unit Lt. Comdr. Shimazaki Lt. Comdr. Shimazaki Type 97 Carrier Attack Plane 27 54 171 Horizontal Bombing Attack One 250-kg Land Bomb. Six 60-kg Ordinary Bombs Air Bases. Hickam Kanehoe Ford Island Ewa
5 Attack Unit Lt. Ichihara 27
2 Group 13 Attack Unit Lt. Comdr. Egusa Type 99 Carrier Bomber 18 81 Dive Bombing Attack One 250-kg Ordinary Bomb Aircraft Carriers Cruisers
14 Attack Unit Lt. Kobayashi 18
11 Attack Unit Lt. Chihaya 18
12 Attack Unit Lt. Makino 27
3 Group 1 Fighter Striking Unit Lt. Shindo Type Zero Carrier Fighter9 36 Air Control and Strafing Attack Two 20mm MGs
Two 7.7mm MGs
1. Airborne airplances
2. Strafing of Grounded Airplanes Hickam Ford Island Wheeler Kaneohe
2 Fighter Striking Unit Lt. Nikaido 9
3 Fighter Striking Unit Lt. Iida 9
4 Fighter Striking Unit Lt. Nono 9


Appendix 4

Combat Air Patrol
Patrols Type of
Number of
Ship On
Which Based
Type of Patrol
Patrol 1 Type Zero
Carrier Fighter
18 54 Akagi
Direct Air Escort
Patrol 2 18 Soryu
Airplanes Ready on Flight Deck
Patrol 3 18 Zuikaku
Airplanes Ready on Hanger Deck
(Fueled and Armed)
NOTES 1. Direct air escort was carried out from an hour before sunrise until 45 minutes after sunset.

2. The patrols alternated every two hours.


Appendix 5



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