Title banner: Pearl Harbor * Why, How, Fleet Salvage and Final Appraisal

CHAPTER VI
Japanese Attack, Strategy, and Tactics

1. PREPAREDNESS, WAR GAMES, AND DRILLS

The attack on Pearl Harbor was the brain-child of Admiral Isoruku Yamamoto, the Commander-in-Chief of the Japanese Combined Fleet. He was well schooled in American ways, having had a tour of duty in Washington. Moreover, he was well regarded by American officers, was a sophisticated poker player, giving to successful bluffing. [1] He was regarded as bold and venturesome. But, to some he was head-strong and lacking in prudence.

He had worked his way up in the Japanese Navy, was vice-minister in 1939, but became the Commander-in-Chief of the Combined Fleet in 1941 due to his familiarity with aircraft and carriers. He was a proponent of the attack on Pearl Harbor. The purpose was to sink or cripple large units so as to immobilize the Pacific Fleet while the Japanese invaded the Philippine Islands, the East Indies, and improved the defenses of the Mandates.

Thus a perimeter could be drawn which would discourage the United States, British, and Dutch responses and would in due time destroy the American will to fight an enemy so far from home.

Yamamoto proved an aggressive naval commander. He carried through the attack on Pearl Harbor, as well as the naval operations against other points in the South, proving to an unbelieving world that the Japanese were capable of more than one major offensive at the same time. Fortunately for the Allied Powers, especially the United States, Yamamoto's plane was shot down in April 1943 while on a naval inspection trip to the Solomon Islands.

In January 1941 Rear Admiral Onishi was appointed Chief of Staff of the Japanese Eleventh Air Fleet and ordered to make a study of the Pearl Harbor operation. In early September 1941 Admiral Nagano, Chief of General Staff, and selected members of the Combined Fleet and the First

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Air Fleet commenced work on details of the actual plan of attack. It was then that the attack on Pearl Harbor was played several times on the war game-board and each time it showed a successful attack with a maximum loss of about one-third of the Japanese force, including airplanes.

By August 1941 or earlier aviators were trained to drop torpedoes from very low altitudes; the torpedoes were fitted with wooden fins or stabilizers to prevent diving. To defeat nets around capital ships, the aviators were trained to use bombs from high-level planes and diving planes. Some of these bombs were made over from 14 or 15-inch armor-piercing shells in order to penetrate the armored decks or turret tops of battleships.

The Japanese were fully aware of the U.S. Fleet doctrine to get underway in case of attack and to pass out to sea through Pearl Harbor's narrow entrance channel. To take full advantage of this eventuality the Japanese stationed five fleet submarines near the entrance and had about thirteen more submarines on patrol duty in other areas bordering Hawaii. These submarines left Yokohama on 11 November 1941 and sailed by different routes.

Five of the large submarines carried midget submarines on their decks.

Image: USN NR&L (MOD) 37386 Fleet Admiral Isoroku Yamamoto, IJN, Commander-in-Chief Combined Fleet.
USN NR&L (MOD) 37386
Fleet Admiral Isoroku Yamamoto, IJN, Commander-in-Chief Combined Fleet.

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The midgets were to enter Pearl Harbor if they could and fire torpedoes against the capital ships. The midget submarines had only two men aboard, carried only two small torpedoes, and were about seventy-nine feet long. After launching midget submarines from their decks not later than the evening of 6 December, the large submarines were to patrol around Hawaiian waters to intercept enemy ships leaving Pearl Harbor. In no case were submarines to attack prior to the air attack.

2. ASSEMBLING OF ATTACK FORCE

The task force under command of Vice Admiral Nagumo, assembled at Hitokappu Bay on the island of Erotufu in the Aleutian Islands of Japan on 22 November 1941, although some of the vessels had come earlier. The assembling of ships was spread out as utmost secrecy was to be observed. The government knew of the proposed attack on the United States Fleet but this knowledge was withheld from all not directly connected with the project. The Emperor knew of the plan in general, but the attack was not to occur until after the message concluding negotiations with the United States Government was delivered.

Complete radio silence was practiced and some radio deception was engaged in. Careful planning of the route to Pearl Harbor was undertaken and the northern route was chosen despite anticipated bad weather for refueling in order to avoid meeting other ships and to make detection less likely.

Prior to departure the aviators were deemed sufficiently trained, and refueling exercises had proved very successful. The task force sailed for Pearl Harbor on 25 November 2941, United States time.

3. ROUTE OF THE PEARL HARBOR ATTACK FORCE

The Pearl Harbor attack force proceeded along the track shown on page 89. The force operated under certain instructions which should be mentioned. "X" Day [2] was selected as 7 December (U.S. time) because it was Sunday. A few days later would have been more desirable because of

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the darkness of the moon. The refueling was undertaken on 3 December (U.S. time) without mishap.

No shipping was encountered, but if the attack force was discovered prior to "X-2" day the force was to return to Japan without executing the attack. If discovered prior to "X-1" day the decision became the responsibility of the attack force commander, but if discovered on "X-1" or "X" day the attack was to continue. If the United States Fleet interfered in any way it was to be attacked and sunk.

On 1 December 1941, (U.S. time) the Japanese Naval General Staff approved the Pearl Harbor attack. This was supplemented by the approval of the Commander-in-Chief of the Combined Fleet, Admiral Yamamoto. The orders issued are given below. [3] The times given are Japanese times which are one day later than United States times.

5 November 1941

From: The Chief of Naval General Staff

To: CinC Combined Fleet

1. In view of the fact that it is feared war has become unavoidable with the United States, Great Britain, and the Netherlands, and for the self preservation and future existence of the Empire, the various preparations for war operations will be completed by the first part of December.

2. The CinC of the Combined Fleet will effect the required preparations for war operations.

3. Execution of details will be as directed by Chief of the Naval General Staff.

7 November 1941

From: CinC Combined Fleet

To: First Air Fleet

The Task Force, keeping its movement strictly secret, shall assemble in Hitokappu Bay by 22 November for refueling.

Note: (Upon arrival at Hitokappu Bay all ships with a limited cruising range were deck loaded with drums of fuel and oil was stowed in all available spaces inside the ships.)

25 November 1941

From: CinC Combined Fleet

To:  First Air Fleet

(Pearl Harbor Attack Force)

The task force, keeping its movement strictly secret and maintaining close

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guard against submarines and aircraft, shall advance into Hawaiian waters, and upon the very opening of hostilities shall attack the main force of the United States Fleet in Hawaii and deal it a mortal blow. The first air raid is planned for the dawn of X-day (exact date to be given by later order).

Upon completion of the air raid, the task force, keeping close coordination and guarding against the enemy's counterattack, shall speedily leave the enemy waters and then return to Japan.

Should the negotiations with the United States prove successful, the task force shall hold itself in readiness forthwith to return and reassemble.

25 November 1941

From: CinC Combined Fleet

To: First Air Fleet

(Pearl Harbor Attack Force)

The task force, keeping its movement strictly secret, shall leave Hitokappu Bay on the morning of 26th November and advance to 42° N. 170° E. on the afternoon of 3 December and speedily complete refueling.

1 December 1941

From: The Chief of Naval General Staff

To: CinC Combined Fleet

Japan under the necessity of her self-preservation, has reached a decision to declare war on the United States of America, British Empire, and the Netherlands. Time to start action will be announced later. The CinC Combined Fleet shall, at the start of war direct an attack on the enemy fleet in the Hawaiian area and reduce it to impotency using the First Air Fleet as the nucleus of the attack force.

Note: (The above despatch was issued by Admiral Nagano under authority delegated by Imperial Order. The commencement of hostilities was decided upon by Cabinet Council on 1 December.)

2 December 1941

From: The Chief of Naval General Staff

To: CinC Combined Fleet

The hostile action against the United States of America, the British Empire, and the Netherlands shall be commenced on 8 December. Bear in mind that, should it appear certain that Japanese-American negotiations will reach an amicable settlement prior to the commencement of hostile action, all forces of the Combined Fleet are to be ordered to reassemble and return to their bases.

Note that if the American government agreed to the Japanese demands

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the attack force would not attack but would return to their bases. The likelihood for this was remote indeed. Yet the Japanese diplomats were kept active in Washington as it was intended that they should not present the final note until one-half hour before the scheduled time of the Pearl Harbor attack. Actually they did not present it until after the attack, due to their own delay.

Of course the diplomatic efforts were not successful and as a result the Japanese attack force continued. It received the signal "Climb Mount Niitaka" on "X-1" day, which was the order to attack. The attack force arrived at its destination, 200 miles north of Oahu at 0730 on 7 December 1941 (U.S. time). The first air attack took off from the carriers at 0600, preceded by two float planes each from two heavy cruisers. These visited Pearl Harbor and Lahaina Roads and reported "all clear."

The strategy of the Japanese was to immobilize the various air bases on the Hawaiian island of Oahu so that fighter planes could not get into the air and offer opposition.

4. THE ATTACK FORCE

The attack force consisted of the following six aircraft carriers: Akagi, Kaga, Soryu, Zuikaku, Hiryu, Shokaku. To these had been added a number of seasoned aviators from carriers not included in the attack force.

The Screening Unit had the mission of furnishing cover. This unit was composed of one light cruiser and nine destroyers. The Support Force was composed of two battleships and two heavy cruisers.

The Patrol Unit was three "I"-type submarines which preceded the attack force and patrolled the ship lanes. In addition there were eight tankers which returned to Japan following the refueling on 3 December.

5. THE ATTACK

The force launched 360 planes. The first wave of 189 planes took off at 0600 under command of Commander Fuchida. The second wave of 171 planes, under command of Lieutenant Commander Shimazaki, were scheduled to take off one hour and fifteen minutes later. Because these overlapped somewhat, and because the second wave was about fifteen minutes ahead of

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Image: TASK FORCE TRACK CHART
Japanese Task Force Track Chart

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Image: USN NR&L (MOD) 37322 Admiral Chuichi Nagumo, IJN, Commander-in-Chief First Air Fleet and Commander Pearl Harbor Striking Force.
USN NR&L (MOD) 37322
Admiral Chuichi Nagumo, IJN, Commander-in-Chief First Air Fleet and Commander Pearl Harbor Striking Force.

schedule, United States observers at Pearl Harbor were unable to state accurately when one wave ended and another began.

In addition to the 360 planes in the attacking wave, the carriers retained 54 type Zero fighters to take turns as combat air patrol. The patrols alternated every two hours and continued from an hour before sunrise until forty-five minutes after sunset.

The first wave consisted of 50 horizontal bombers each carrying an 800 kilogram (1760 pounds) armor-piercing bomb, 40 torpedo planes each carrying an 800 kilogram [4] aerial torpedo, and 54 dive-bombers each carrying a 250 kilogram land bomb as well as machine guns for strafing. In addition 45 fighters were over these planes for air control and strafing attack as might be required.

The targets of the horizontal bombers, attacking from 10,000 feet, and the low flying torpedo planes were the battleships and carriers. The battle-

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UNIT COMMANDER TYPE OF
AIRPLANE
NUMBER OF
AIRPLANES
TYPE OF
ATTACK
ARMAMENT
EACH AIRPLANE
TARGET
FIRST
ATTACK
UNIT
1
GROUP
(SHUDAN)
1 ATTACK UNIT COMDR
FU-
CHIDA
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 HASHICHUCHI 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
ERIAL
TORPEDO
BATTLESHIPS
AIRCRAFT
CARRIERS
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
BOMBS
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 81 AIR CONTROL
AND
STRAFING
ATTACK
TWO 20-MM MGS
TWO 7.7-MM 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
6 FIGHTER STRIKING UNIT LT KANEKO 6
5 FIGHTER STRIKING UNIT LT SATO 6
SECOND
ATTACK
UNIT
1
GROUP
6 ATTACK UNIT LT.
COMDR
SHIMA-
ZAKI
LT. COMD SHIMAZAKI TYPE
97
CARRIER
ATTACK PLANE
27 54 171 HORIZONTAL
BOMBING
ATTACK
ONE 250-KG LAND
BOMB SIX 80-KG
ORDINARY BOMBS
AIRBASES
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
250-KG
ORDINARY BOMBS
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
FIGHTER
9 36 AIR CONTROL AND
STRAFING
ATTACK
TWO 20-MM MGS
TWO 7.7-MM MGS
1. AIRBORNE
AIRPLANES
2. STRAFING OF
GROUNDED
AIRPLANES
HICKAM
FORD ISLAND
WHEELER
EWA
KANEOHE
2 FIGHTER STRIKING UNIT   LT NIKAIDO 9
3 FIGHTER STRIKING UNIT LT IIDA 9
4 FIGHTER STRIKING UNIT LT NONO 9
     

Japanese Aircraft Attack Organization

ships were mostly secured in pairs, so that the inboard battleships could not be reached with torpedoes. Therefore the horizontal bombers intended to hit inboard battleships with enough large armor-piercing bombs to put them out of commission. It is well to remember that the ships were entirely stationary while the Japanese airplanes were operating in ideal visibility and wind conditions.

The first objective of the dive-bombers was the air bases at Ford Island and Wheeler Field where the fighters were located. The air patrol was to strafe the air bases if the United States fighters failed to appear. They were also to attack the air bases at Ford Island, Hickam, Wheeler, Ewa, Bellows, and Kaneohe with their 20 millimeter [5] and 7.7 millimeter machine guns.

The second wave consisted of 54 horizontal bombers each carrying one

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250 kilogram bomb and six 60 kilogram bombs. In addition 36 fighters were overhead to meet Hawaiian based fighters or for strafing airfields with their 20 millimeter and 7.7 millimeter machine guns. The mission of the horizontal bombers was the various air bases, while the objectives of the dive-bombers were the major ships of the Pacific Fleet.

The attack started at Wheeler and Ford Island at 0755, while the torpedo planes attacked the battleships at 0757. The grounded aircraft were attacked at 0800 and the horizontal bombers got into action about 0805. It was estimated that although the 250 kilogram bombs would not pierce the armored decks of the battleships they would be effective against cruisers and carriers. But finding no carriers present, these bombs were directed against battleships.

The Japanese torpedoes were especially effective. There were no torpedo nets spread for the protection of battleships, and each battleship was a stationary target which could hardly be missed by the forty torpedo planes flying 50-100 feet above the water. We were to learn that Japanese torpedoes were more lethal than American torpedoes; first, because they had been tested for explosive effect whereas American torpedoes had not been so tested on grounds of economy; secondly, because the Japanese used oxygen, which is highly explosive, instead of air for propulsion of torpedoes; and thirdly, because the torpedoes carried an explosive charge of over 1000 pounds as compared to the American charge of about 500 pounds.

The question was asked why torpedo nets were not used by the fleet, and why captive balloons were not employed. The answers are very simple. Due to the restricted area, and the need for seaplane lanes for taking off and landing, torpedo nets could not be used. Balloon barrages were considered undesirable because they interfered with our own aircraft over the fleet. Probably, the best answer is that these items were not available in sufficient quantity at that time.

6. DIRECTION OF ATTACK

The illustration on page 93 gives the plan of attack, and indicates the reason local observers concluded that the planes came from a southerly direction. It will be noted that the first wave was to leave the northerly rendezvous at 0740 and the second wave at 0850. The torpedo bombers

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Image: AIRCRAFT APPROACH TO OAHU
Aircraft Approach to Oahu

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were to approach the battleships from the port beam, which they did with disastrous results.

Each aviator had a chart or map showing the exact location of his target. Finding no aircraft carrier in Pearl Harbor, these fliers used some of their ammunition on battleships and some on the old battleship Utah which had been converted to an aircraft target ship. She was presumably identified by some aviators as an aircraft carrier.

7. SUBMARINES

The damage caused by the submarines stationed at the entrance to Pearl Harbor was negligible. Of the five midget submarines all were eventually lost without inflicting any damage. No ship was damaged by torpedoes fired from the "I"-type submarines on patrol duty after launching their midget submarines. One "I"-type was lost on 10 December in an attack by Enterprise planes. The fleet type submarines were on patrol duty in the Hawaiian area until early January, but caused no damage. Thereafter they were on the West Coast of the United States, accomplishing only minor results.

8. JAPANESE LOSSES

After completing its mission each Japanese aircraft was to return to its carrier. The losses reported from American sources were frequently duplicated and gave an inflated figure. Japanese admissions after the surrender  presumably gave a true picture and were as follows:

Aircraft in first wave:
Fighter Planes
3
Dive-Bombers
1
Torpedo Bombers
5
Total
9
Aircraft in Second wave:
Fighter Planes
6
Dive-Bombers
14
Total
20
Grand total of aircraft lost:
29

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Image: USN NR&L (MOD) 39733 Japanese midget submarine No. 19
USN NR&L (MOD) 39733
Japanese midget submarine No. 19

The losses of the Japanese do not include planes lost or damaged when returning to the carriers.

Submarines lost:
Fleet type "I"
1
Midget type
5
Total
6[6]

The airplanes returned to their carriers immediately after rendezvousing with their fighters at a point about 20 miles bearing 340° from Kaena Point. The aircraft carriers were underway for Japan at that time. There was no rearming of airplanes for renewed attacks on Pearl Harbor. Admiral Nagumo felt that the mission was completed and he was intent on getting clear of the area as quickly as possible as had been ordered. He was somewhat afraid of an attack by American carrier planes whose whereabouts

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were unknown, and from land based pursuit planes of the Army at Pearl Harbor. Nagumo assumed that as many as fifty of these were operable after the attack.

He had one mission yet to perform. On his return voyage to Japan he detached two aircraft carriers, two heavy cruisers, and two destroyers for an attack on Wake Island.

9. JAPANESE ESTIMATES OF DAMAGE TO THE AMERICANS

From pilot reports and photographs taken from attack planes of the second wave the Japanese estimate was:

Ships damaged or sunk:

Sunk—4 battleships, 1 cruiser, 2 tankers

Heavily damaged 4 battleships

Lightly damaged 1 battleship

Aircraft shot down or damaged:

Shot down 10

Destroyed on the ground 250 [7]

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Footnotes

1The Campaigns of the Pacific War, United States Strategic Bombing Survey, Naval Analysis Division, Washington, D.C., 1946, p. 13. Hereafter cited as Campaigns.

2 "X" Day in military parlance means the day of actual attack or opening of hostilities.

3 Paraphrased versions of these orders may be found in Hearings, Part 13, pp. 415-417.

4 One kilogram is about 2.2 pounds.

5 One millimeter equals 1/1000 of a meter. One meter equals 39.37 inches.

6 Campaigns, pp. 18 and 19.

7 Ibid., p. 19.

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