Foreword (The NACHI Affair)
She lay in a little over 100 feet of water five nautical miles southwest of Corregidor. Less than two weeks after the Leyte Gulf defeat aircraft of Task Group 38.2 found her and on November 5, 1944 sank her. When Manila Bay was finally secured in April 1945 submarine rescue ship USS CHANTICLEER was brought in to work the various wrecks in the Manila Bay area. NACHI was the crown jewel. The divers went to work on April 14. Almost immediately they were bringing up the secret orders of the Japanese Navy. By the time they were finished they had one of the largest single intelligence coups of the war. A portion of the recovered items consisting of Operations Orders, Doctrinal Orders and the like were translated and published in a twelve volume set which was given limited distribution.
Even a brief summary of the translated documents illustrates the magnitude of the find:
I. SHO GO OpOrds (Leyte Gulf OpOrds)
II. NIGHT FORCE DOCTRINE
III. MOBILE FORCE DOCTRINE
IV. NORTHEAST AREA FORCE DOCTRINE and SECOND BASE AIRFORCE OPORDS, 1943-4
V. SECOND DIVERSION ATTACK FORCE DOCTRINE 1944
VI. OMINATO GUARD DISTRICT OPERATIONS ORDERS 1943-4
VII. COMBINED FLEET DOCTRINE 1943 COMBAT
VIII. OPORDS 1941-4
IX. DESTROYER DOCTRINE AND PROCEDURE
X. CARDIV 4 DOCTRINE, CRUISER DOCTRINE, DIVERSION ATTACK FORCE DOCTRINE, IDENTIFICATION OF FRIENDLY FORCES
XI. NORTHERN FORCE ORDERS, COMMUNICATIONS LESSONS OF THE BATTLE OF ATTU
XII. SOUTHERN FORCE ORDERS
During most of the war NACHI served as fleet or division flagship so she was on the distribution list for most operational and doctrinal publications. She was assigned to Cruiser Division 5(5S) Second Fleet (2K) until July 1942 when she was transferred to 21S 5K. While with 2K she participated in the Battle of the Java Sea. Most of her career with 21S involved regional defense and convoy operations in the north Pacific. She ended her run as did many Japanese warships, in the Battle for Leyte Gulf and its aftermath.
This is not an operational history nor is it intended as a comprehensive treatment of Japanese Tactics and Doctrine. During the war the U. S. Navy captured many sensitive Japanese documents which were translated and given “need to know” distribution. This is not a treatment of that body of work, but a discrete look at the largest single collection.
Distribution of 40 copies of the translations to 15 addressees began almost immediately with the first installment going out on April 22.
All are arranged in the same format. Following the transmittal is a bibliographical subject index, arranged by key numbers for easy merging with similar data from other sources, a contents summary, reference to glossaries of Japanese terminology, English-Japanese translations of recurring terms with KANJI and ROMAJI renderings of the Japanese words that are not subject to translation (proper names, places, ship names and, in rare situations, technical terms that defied translation or were of uncertain meaning at the time), tactical terms, plotting symbols (IJN), and a group of numbers identifying the translators who handled the document, followed by the translated documents.
Generally the documents are translated without comment. Proper names are rendered in ROMAJI in the text with their KANJI in the footnotes. Formation diagrams and the like are traced directly from the originals without comment. Typically Operations Orders and Doctrinal Publications consist of two documents; the transmittal cover and the appended order.
By the time the documents found in NACHI were published the Japanese Navy’s run was over. The strategic blunder of war with the United States Navy had come home. In the Marianas the failure of the carrier air groups was so humiliating it blurs Admiral Ozawa’s performance. At Leyte Gulf, in three days the Navy lost more ships than it had in the entire Guadalcanal campaign. In those two battles the Japanese still did some things well, but it did not matter.
Some of the operations orders found in NACHI have been published elsewhere and will not be republished here. Instead the emphasis will be on doctrine. The method will be presentation of parts of the text. This will be put in context by reference to contemporary U. S. documents and the battle lessons the IJN brought from the 1942-3 fighting.
In KAIGUN Mark Peattie and David Evans close accounts on the IJN at the end of 1943. The bulk of the doctrinal publications recovered from NACHI begin where Peattie and Evans leave off. These documents reflect many of the lessons the Japanese took from the fighting in 1942-3 and their attempt to apply those lessons to the upcoming campaigns.
1 Task Force Ultrasecret Operation Order 76 and 77; Order 76 and Serials 108, 1003 and 1084 Sho-Go
The first set of documents translated and distributed related to the Battle for Leyte Gulf. Portions of these orders have been published elsewhere, though the various cruising and approach orders have not, nor has the outline of movements.
Documents related to Sho-Go, the Operation that led to the Battle for Leyte Gulf
Task Force Ultra Secret Operations Orders 76 and 77; Order 76 and Serials 108, 1003 1084(1944).
1. Task Force Ultrasecret Operation Order 76 and 77, 10 August 1944: Outline of Operations of the Task Force in SHO Operations.
a. General Policy for operations
b. Concrete operational policy: Outline of SHO 1, 2, 3 and 4 Operations.
c. Allocation of Forces: Lists commanding officers, strength and main
duties in Allocations of Forces 1 to 4.
d. Combat methods
e. Air Combat: Disposition for attack, outline for air combat.
f. Outline of operations: Various unit operations which the situation may
rise to before the main engagement, outline of battle, anchorage.
g. Supply
h. Communications (ship and airplane)
i. Order of cruising under alert (KEIKAIKOKO), General rules,
sketches showing various orders.
j. Order of approach (two sketches)
k. Separate charts, Outline of movements for SHO 1, 2, and 4 Operations
and for Bonin Island Area Operations.
2. Task Force Ultrasecret Serial 108 17 Aug. 1944 (Errata for #76)
3. Task Force UltraSecret Serial 1003, 10 Aug 1944, Statement of Chief of Staff on Task Force operations in Sho Operations.
4. Task Force Ultrasecret Serial 1003, 10 Aug 1944-Plan for table top
Maneuvers 6. Daily schedule and place, principal items for training and
study (Task Force operation in the Sho Operations), organization of
supervisory personnel and maneuver personnel, etc.
5. Task Force Ultrasecret Operation Order 77 “Plan for carrying out base air
defense while in training on the mainland.
6. Task Force Ultrasecret Serial 1004 10 Sept. 44 Main points in training task force Hikokitai. Employment of aircraft, maintenance, communications.
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2. Night Operations Force Doctrine
This volume was translated and distributed in May 1945. It consists of two parts: Second Fleet Night Operations Doctrine and Fifth Fleet Night Operations doctrine.
If you are familiar with Peattie and Evans’ treatment of their night operations doctrine of the late 1930s you might be struck by how little has changed. The drawing in the 1944 doctrine has changed to fit the ships that were available in 1944. The idea of surrounding the American force is still central to their tactical scheme.
Here are some USN hypothetical formations that might have encountered the Japanese Night Operations Force as well as it daylight version; Diversion Attack Force:
For simplicity battleship formations that were either contemplated or actually organized are used:
Task Group 58.7 (June 1944)
WASHINGTON, NORTH CAROLINA, IOWA, NEW JERSEY, SOUTH DAKOTA, ALABAMA, INDIANA, WICHITA, MINNEAPOLIS, NEW ORLEANS, SAN FRANCISCO, 13 DDs
Task Force 34 (October 1944)
IOWA, NEW JERSEY, MASSACHUSETTS, WASHINGTON, SOUTH DAKOTA, ALABAMA, VICKSBURG, HOUSTON, MIAMI BILOXI, CHESTER, PENSACOLA, SALT LAKE CITY, 18 DDs
Task Group 34.5 (October 1944)
IOWA, NEW JERSEY, VICKSBURG, HOUSTON, MIAMI, BILOXI, VINCENNES, 5 DDs
Old Battleship Force at Surigao:
MISSISSIPPI, MARYLAND, WEST VIRGINIA, TENNESSEE, CALIFORNIA, PENNSYLVANIA, LOUISVILLE, PORTLAND, MINNEAPOLI, PHOENIX, BOISE, HMAS SHROPSHIRE DENVER, COLUMBIA, 28 DDs
Admiral Oldendorf’s detachment sent north to meet Admiral Kurita’s Force:
TENNESSEE, CALIFORNIA, PENNSYLVANIA, SHROPSHIRE, LOUISVILLE, PORTLAND, INDIANAPOLIS, 20 DDs.
By the time Kurita had reached the open water outside San Bernadino Strait his force was so reduced that would not have had the ships to man all the stations envisioned in the plan.
3. Mobile Fleet Doctrine
The third item translated was Mobile Fleet Doctrine. In March 1944 there was a major reorganization of the combat arm of the Japanese Navy. Almost all ships, destroyer size and larger, not assigned to area fleets, were put under one administrative command, First Mobile Fleet (Dai Ichi Kido Kantai). On March 25 Admiral Ozawa issued First Mobile Fleet Doctrine. It would serve as the doctrine for the upcoming fights in 1944 and as such will be given extended treatment. Most of the following is a synopsis of what is in the original text. Portions that are quotes are noted.
MOBILE FLEET DOCTRINE
Mobile Fleet Doctrine starts with this premise, “Combat by First Mobile Fleet is based on the fundamental policy
of complete dependence on air attack. The aim is to take the initiative bringing the
full strength of the air forces to bear through close cooperation of all forces, first to
destroy the enemy aircraft carriers; then employ the full strength of the fleet to pursue and annihilate the remaining enemy forces.” with six methods envisioned:
Combat Method 1: Mobile operations would be carried out using disposition in depth by the main unit and the vanguard[1].
Combat Method 2: Envelopment dispositions were to be used. There were two versions. In the first the force would divide into two groups, and in the second (referred to as Method Ko) the force would divide into three groups.
Combat Method 3: The force was to mass in one group and carry out mobile operations.
Combat Method 4: The majority of the air groups (Hikokitai) will operate from land bases and the remainder of the strength will remain afloat. In a second version (Method Otsu) the majority would remain on the carriers but a part would operate from land bases. In either case the surface forces would be given special tactical orders.
Combat Method 5: Diversionary movements were to be carried out with a designated force to decoy the enemy carrier group. Advantage would be taken of the fact the enemy carriers were limited by their movements in response to the decoy operations.
Combat Method 6: A shift to the decisive battle with surface combat forces and carriers in a supporting role.
Combat Method 7: The enemy transport convoys or invasion force would be attacked.
- Attack Dispositions
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- Air Combat
- Surface Mobile Operations
- General Policy for Air Combat
- Dawn Air Combat: Dawn air attack was preferred. Contact would be maintained during the night. Mobile Force was to close the range and in the pre dawn hours the Zero fighter bombers would attempt to disable the enemy carriers with the main attack coming at dawn. Every effort was to be made to conceal the approach of Mobile Force with scouting conducted in waves. The pursuit of a defeated enemy force was to be relentless. Note: at this time the Zero fighter bomber force was referred to as “Tokubetsu Kogeki Tai” (i.e. “Special Attack Force”) a tactical designation later used by the Kamikazes. The use of this term at this time should not be confused with its later use.
- Day Air Combat: Day air combat emphasized stand off tactics taking advantage of the superior range of Japanese aircraft with the range being closed only after the enemy carriers had been disabled or destroyed.
- Dusk Air Combat: Dusk air attacks were discouraged unless day air combat had not completed the destruction of enemy forces or the tactical situation outweighed the disadvantages of such attacks. In the event of dusk air combat the commander of Mobile Force might separate the carriers from surface units and dispatch the latter to “increase the results” of the dusk air attacks. The carriers were to avoid the battle area and at the same time remain close enough to exploit night or dawn air combat situations. Preferably the carriers were to operate to windward of the battle area.
- Night Air Combat: Night air combat was not recommended for carrier air groups because of the problems involved in night recovery. If, however, moonlight, starlight
In August a Signal Appendix was issued (whether this replaced a previous appendix or not is unclear from the text, though there is no indication it did).
Appendix
I Order of Cruising Under Alert (Keikaikoko)
II. Circular Formations
Circular Formations and special signals are determined as follows:
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Formation |
Notes |
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Take Circular Formation A |
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Take Circular Formation B |
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Jin ZC
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Take Circular Formation C |
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Jin ZD
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Take Circular Formation D |
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Jin ZE
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Take Circular Formation E |
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Jin ZF
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Take Circular Formation F |
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Jin ZG
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Take Circular Formation G |
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Jin ZH
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Take Circular Formation H |
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Jin ZI
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Take Circular Formation I |
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Jin ZK
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Take Circular Formation K |
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Jin ZL
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Take Circular Formation L |
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Jin ZM
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Take Circular Formation M |
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Jin ZN
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Take Circular Formation N |
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Jin ZO
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Take Circular Formation O |
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Jin ZP
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Take Circular Formation P |
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Jin ZQ
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Take Circular Formation Q |
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Jin ZR
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Take Circular Formation R |
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Jin ZS
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Take Circular Formation S |
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III. Antisubmarine Formations
Antisubmarine Formations Antisubmarine formations and special signals for those formations used when a direct escort is assigned to a carrier division (battleship division) are established as follows:
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Antisubmarine Formation |
Notes |
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Jin 2A
(Jin7A)
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Employ Antisubmarine Method A, sections in Column in numerical (reverse) order. (Employ Antisubmarine Method A, sections in Line in numerical (reverse) order. |
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1. Order when omitting The direct escort ship (7)(0) 2. Group 1, Section 1 (0)(1)(3)(5) (Section 1 [0][1][2][3] Group 2, Section 2 (2)(4)(6)(7) (Section 2 [4][5][6][7] (Note) The figures in Brackets apply when the signal Jin 7A is given. The same applies below. |
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Jin 2B
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Employ Antisubmarine Method A, sections in Column in numerical (reverse) order.
(Employ Antisubmarine Method B, sections in line In numerical (reverse)order) |
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The direct escort ship 7 (0)
[Section 1 (0)(1)(2)(3) Group 2, Section 2 (2)(4)(6)(7) [Section 2 (4)(5)(6)(7) The figures in brackets apply when the signal Jin 7A is given |
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Jin 2C
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Employ Antisubmarine Method C in numerical (reverse)order. (Employ Antisubmarine Method C, sections in line in numerical order. |
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When the direct escort is missing omit (0) |
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Jin 8A
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Employ Antisubmarine Method A using triangular Formation, Odd numbers on the right (left) |
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Group 2 (II)(2)(4)[(II)(1) (3)
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Jin 8B
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Employ Antisubmarine Method B using triangular formation, odd numbers On the right (left) |
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When the direct escort is missing omit (0) |
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Jin 8C
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Employ Antisubmarine Method C using triangular formation, odd numbers on the right (left) |
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Group 2 (II)(2) [(I)(2) [(II)(1) Group 3 (III) (3)(4) |
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Jin 6A
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Employ Antisubmarine Method A, single line in numerical (reverse) order |
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Group 2 (II)(2)(4)(6)(8) [(II)(1)(3)(5)(7) |
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Jin 6B
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Employ Antisubmarine Method B, single line in numerical (reverse) order |
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Group 2 (II)(2)(4)(6) [(II)(1)(3)(5)] |
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Jin 0A
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Employ Antisubmarine Method A, single column in numerical (reverse) order |
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Group 1 (I)(0)(1)(2)(3) [(I)(4)(5)(6)(7) Group 2 (II)(4)(5)(6)(7) [(II) (0)(1)(2)(3) |
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Jin 0B
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Employ Antisubmarine Method B single column in numerical (reverse) order |
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Group 2 (II) (5)(6)(7) [(II) (1)(2)(3)(4) |
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Jin 0C
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Employ Antisubmarine Method C single column in numerical (reverse) order |
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Group 2 (II)(3)(4) [(II)(0)(1)(2) |
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IV. Order of Approach
V. Standard Landing and Take off Procedure
The formation and special signals for take-off and landing of airplanes of a carrier division will be in accordance with the following:
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Text |
Formation |
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Un Ko 1
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Assume Take-Off and Landing Formation 1 |
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Un Ko 2
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Assume Take-Off and Landing Formation 2 |
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Un Ko 3
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Assume Take-Off and Landing Formation 3 |
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Un Ko 4
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Assume Take-Off and Landing Formation 4 |
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Un Ko 5
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Assume Take-Off and Landing Formation 5 |
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Un Ko 6
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Assume Take-Off and Landing Formation 6 |
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VI. Various Regulations for taking on Airplanes
VII. Standard Procedure for Avoiding Torpedo and Bombing Attacks
VIII. Standard Ship-borne Radar Search Procedure
IX. Standard Formations for Supplying
X. Signal Communications Systems
XI. Prearranged Signals (Signal Appendix)
4. Northeast Area Force Doctrine and Second Base Air Force OpOrds 1943-1944
I do not have this volume
5. Second Diversion Attack Force Doctrine
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Vol 5 Diversion Attack Force Ultrasecret Operations Orders and Orders 1944 |
Second Diversion Attack Force Ultra Secret Operation Orders |
Operation | ||||
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Orders and Orders |
1944 |
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I. Standing order 10 Organization of Fifth Fleet (2YB) in | |||||
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SHO Operation |
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II. Plan of Operations (SHO), distribution of forces, outline | |||||
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of operation, supply and charts showing movement plans | |||||
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fpr SHO 1, 2 & 4 |
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III. Plan for Supply SHO |
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IV. Support Unit (Betsudo) Regulations for SHO |
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V. Plan for SHO Table Top Maneuvers |
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VI. Identification of Friendly Forces in SHO |
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VII. ASW screen by 954 & 955 Kokutai for 1YB and |
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5. Ominato Guard district Operations Orders 1943-4 I do not have this volume | ||||||
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7. Combined Fleet Doctrine: 1943 Combat General Principles: The basic evolution unit for Japanese battleships (and heavy cruisers) was the squadron or division (Sentai) designated by the Arabic numeral-Roman letter “S” combination which corresponded to its squadron number thus; 1S=Battleship Division 1. The first three numbers were reserved for battleships, the balance to heavy cruisers. Standard distance for battleships was 800 meters. Speed signals are treated in the signal appendix.
Acceleration for battleships in minutes: seconds was as follows: Time required to accelerate from one speed to the next. Total elapsed time Standard speed: 12 knots to 14 knots: 1:00 1:00 Full speed: 14-16 knots 1:00 2:00 Battle Speed 1: 16-18 knots 2:30 4:30 Battle Speed 2: 18-20 knots 2:30 7:00 Battle Speed 3: 20-22 knots 3:00 10:00 Battle Speed 4: 22-24 knots 3:00 13:00 Battle Speed 5: 24-26 knots 4:30 17:30
The Interception Zone Combat, Base Air Force Combat and Air Combat are omitted as they are either not discussed anywhere or are treated elsewhere.
Surface Action: In the approach phase of a battle the Japanese battleship force was to steam in an ALERT CRUISING DISPOSITION or APPROACH DISPOSITION similar to those in the sections on Diversionary Attack or Night Operations (see Chapters 2, 5 and 10) selected by the officer in tactical command or one set out in the operations order for a specific operation.
When contact is obtained the vanguard was to proceed immediately in the direction of the enemy and maneuver to become the leading or rear unit depending on the overall tactical situation.
It was suggested the officer in tactical command dispatch preliminary orders for deployment when the main bodies were about 50 km apart, about 15 minutes before opening gunfire. The guide unit would normally be 1S (YAMATO, MUSASHI)* and the direction of deployment would be ordered at this time. The APPROACH DISPOSITION would be line abreast of lines of divisions at approximate right angles to the direction of the enemy, with the order of battle being a column formation. Prior to deployment the interval between divisions will be maintained at 4 km. unless otherwise signaled.
DAY ACTION: Day actions by surface forces normally were actions on the same course with a concentration on the enemy van. At a suitable time deployment was to be completed. The surface forces would proceed into the path of the enemy force and take up a position which would permit them to overwhelm the enemy van. All forces would cooperate in cornering the enemy main force, then the whole force would concentrate and destroy the enemy. If the enemy deployed for an action on opposite course during the fight, an action on opposite course normally would be carried out.
There were three basic methods for conducting day actions on the same course:
Day Action KO (A): After the battleship divisions had begun the fight, at the first opening the entire force would carry out a strike.
Day Action OTSU (B): When visibility was very good, for awhile the battleship division would fire at long range with the angle of elevation of the main batteries at about maximum. The light forces would maneuver out of effective range of the enemy main batteries. Guns of large caliber and torpedo attacks by the cruiser divisions would be used to create an opening. Then the entire force would make its strike.
Day Action HEI (C): Local superiority would be obtained by drawing up the entire force in a compact formation. One flank of the enemy main force would then be attacked.
Actions KO and OTSU were qualified as follows:
Method 1: The leading unit would move out. Later it would return. At that time deployment would be made.
Method 2: The whole force would be deployed as a unit. Unless otherwise ordered this method would be used.
In effect there were five formats: A1, A2, B1, B2, & C. These would be indicated by appropriate signals.
Employment of vanguard and 3S in Methods KO and OTSU: Method 1: The vanguard would proceed in direction of the enemy to obtain information of the situation. When ordered to deploy 3S (KONGO, HARUNA) take station 8 km obliquely to the rear of 1S (YAMATO, MUSASHI)*. 3S would maneuver so it can begin gun action against enemy main body simultaneous with 1S. Other leading units (heavy cruisers) would endeavor to deliver effective torpedo attacks against enemy main body simultaneous with 1S opening fire, reporting the time of firing and running time to Commander Main Body (1S), maneuvering to take station in the order of battle after firing their torpedoes. Method 2: Same as Method 1 except 3S wouldn’t move out so far.
1S would concentrate fire on the enemy van, signaling the opening of gunfire. Smoke would be used to attempt to divide the enemy. Detached enemy units would be taken under fire before the main gun action opens.
Van and rear guard light forces would, under their commanders, attack the enemy with guns and torpedoes as the opportunity presented itself. In the strike or mop-up phase the entire force would close the enemy attacking fiercely. Cruisers will open the way for destroyers and both cruisers and destroyers will deliver repeated torpedo attacks. Destroyers will attack the enemy main force and guard against possible reversal of course by the enemy main body.
Actions on opposite course were as follows:
Method KO (A): Using the greater part of the light forces an advance would be made into the path of the enemy force, then an attack would be delivered.
Method OTSU (B): The dispositions of the time would be used and an engagement while circling on opposite course would be carried out. Unless otherwise ordered, this method would be used.
Dusk Action: There were two types of Dusk Action. Dusk Action KO (A) was based on Day Action KO. A single decisive action would be fought. This was the preferred method. In Dusk Action OTSU the force was to await night fall with the object of fighting a night action. Then all out action was to be joined. In addition to application of Day Action instructions every attempt was to be made to silhouette the enemy and take advantage of any meteorological phenomena. In Dusk Action OTSU the force will remain concentrated to avoid defeat in detail.
Night Action: There were five types of Night Action. In Night Action KO the entire force acting as a unit would carry out a night against a single target. Night Action OTSU would apply against a divided enemy force. The entire strength would be used to attack and destroy the nearest and most powerful enemy force. Then the rest of the enemy would be dealt with. In Night Action HEI own forces were to be divided to carry out night action against a divided enemy. In Night Action TEI the routed enemy would be pursued and destroyed as in the outline of day pursuit day action. One element would be assigned to deal with damaged enemy ships. In Night Action BO the enemy screen would be avoided and a night action carried out against the enemy main body. The fast battleships of 3S would be the only battleships to actively participate in night fighting, cruisers and destroyers being better adapted to night fighting. The ships of 3S were to be active participants in night actions and were assigned responsibility of cover and advance in Night Operations Force actions.
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8. Combined Fleet Operations Orders, Orders and Serials 1941-4
As indicated by its title this item contains numerous (43 in all) operations orders and the like, many of which have been published elsewhere. All are listed. A synopsis is sufficient for most though a few are set out in part or in full.
1941-2:
1943:
The Model for Change: Combined Fleet Memorandum 13 on Ultra secret Operations Orders, 15 August 1943.
In August 1943 Combined Fleet issued a memorandum to all squadrons, flotilla and division headquarters and to all base headquarters “to indicate the basic future policy of Combined Fleet operations and to attempt to unify concepts regarding the art of war in this period of transition when rules of naval warfare and COMBINED FLEET DOCTRINE are being re-examined.”
On December 5, 1943 COMBINED FLEET DOCTRINE: BOOK ONE (COMBAT) became the first document issued pursuant to this memorandum. It was followed by Second Fleet’s issuance of a series of doctrinal publications: DESTROYER SQUADRON DOCTRINE (12-18-43); DESTROYER SQUADRON PROCEDURE (12-18-43); NIGHT OPERATIONS FORCE DOCTRINE (1-1-44); DIVERSION ATTACK FORCE DOCTRINE (1-1-44) and CRUISER DIVISION DOCTRINE (1-22-44). All of these came from Admiral Kurita’s staff. Third Fleet, the carrier force was a bit slower issuing FIRST MOBILE FLEET DOCTRINE (3-28-44). The latter document was issued by Admiral Ozawa who now commanded the carrier force as well as FIRST MOBILE FLEET (DAI ICHI KIDO KANTAI) an umbrella organization which combined Second Fleet (the battleships and cruisers with their attached destroyer squadron) and Third Fleet (the carrier force with its attached destroyer squadron). The opening sentence of this new doctrine states the reason for this consolidation of the major combatant forces of the navy, “Combat by FIRST MOBILE FLEET is based upon the fundamental policy of complete dependence on air attack.”
Since it bears on so much of the NACHI find Memorandum 13 warrants repeating in full.
I. EXPLANATION OF THE OUTLINE OF COMBINED FLEET OPERATIONS
This memorandum has been issued to indicate the basic future policy of Combined Fleet Operations and to attempt to unify concepts regarding the art of war in this period of transition when rules of naval warfare and COMBINED FLEET DOCTRINE are being re-examined.
II. EXPLANATION OF THE BASIC ORGANIZATION OF VARIOUS FORCES OF THE COMBINED FLEET
From the outset of the war to the present, operations for the most part have been based on pre-arranged plans. Since commanding officers and subordinates trained in the Combined Fleet before the war have conducted most of the action of the fleet, no matter what changes in the fleet have taken place, in general, operations have not been impaired. In the future, however, such will not necessarily be the case. The number of commanding officers and other personnel who are taking up duties and participating in organizations for the first time is increasing, and there will be unusual changes in the grouping of forces. Doctrine, combat regulations (SENSOKU), standard procedure (YOMU JUNSOKU), etc, suitable for each type of tactical unit will be established, therefore concepts regarding the art of war will be unified. Training will be given whenever the opportunity presents. Otherwise there is little hope that the fighting strength of the Combined Fleet can be maintained or improved.
At the present time the OUTLINE FOR COMBINED FLEET OPERATIONS not only established the basis for carrying out Combined Fleet operations, but also fixes the pattern for the basic organization of the forces. In addition, all commanding officers and staff officers will quickly establish doctrine and other matters required for combat.[i]
Training in these matters will be strictly enforced. It is anticipated that all these efforts will replenish and increase the fighting power of the Combined Fleet. These orders are promulgated to this end.
Basic Orders: Basic Organization, First Mobile Force Commander; Basic Organization, Night Operations Force Commander Routine Operations Orders: Previous examples will be relied on.
Because there can be two types of doctrine for individual forces (doctrine for each force in Combined Fleet operations and doctrine for individual forces operating as detached units), when necessary the two types will be set forth separately. However, the force commander concerned will decide whether the doctrine will be placed in one or two volumes.
In basic organizations cruiser divisions and destroyer divisions are included in the Mobile Force, Diversion Attack Force, Night Operations Force, area forces, etc. These orders set forth doctrine for the Mobile Force and area forces and especially points to be applied in operations by cruiser and destroyer divisions. Matters based on doctrine and standard procedure (YOMU JUNSOKU) determined by Diversion Attack Force and Night Operations Force as in the past will be carried out so as to give full scope to the fighting power of such of the so-called light forces. Accordingly in establishing doctrine, combat regulations (SENSOKU) and standard procedure (YOMU JUNSOKU) force commanders will confer whenever necessary to prevent conflicting demands being made on cruiser division, destroyer division and similar forces.
1. Force commanders will form board, and the boards at their discretion may order specially designated commanding officers to carry out the work. It is sometimes wise to obtain the cooperation of naval KOKUTAI, schools, etc. At such times responsible commanding officers will take suitable measures.
2. When doctrine is determined, closest liaison will be maintained with Combined Fleet Headquarters. To coordinate concepts doctrine will be promulgated to all force commanders.
3. It is especially important to promulgate important matters without delay, if necessary in rough draft form.
within fixed commands. For example, Commander in Chief, 3 Fleet will train cruiser divisions and destroyer squadrons of 2 Fleet in their capacity as elements of the Mobile Force, and Commander in Chief 2 Fleet will train cruiser divisions and destroyer squadrons of 3 Fleet in their capacity as elements of Night Operations Force and Diversion Attack Force. Consequently force commanders will lead ships of forces places under their command for operations in accordance with battle experience and a unified conception of the art of war and without regard to the fixed organization of the forces. A unified conception of the art of war is derived from doctrine, combat regulations (SENSOKU) and standard procedure (YOMU JUNSOKU) established beforehand. Training will be given at every opportunity so that operations may be carried out without hindrance of time or division of forces.
Although it is expected that the organization of the Combined Fleet Mobile Force, Especially Organization OTSU, will be under the immediate control of Commander in Chief Combined Fleet, basic organization will be in accordance with these orders.
for the most part to carriers whose chief function is scouting. Further in cases where engagements begin as task force engagements and subsequently become night battles, the Night Operations Force will be responsible for the night combat and some of the aircraft carriers will come under its command. Co-operation and other necessary matters will be considered in terms of establishment of doctrine. (Night combat doctrine is needed even in Mobile Force Doctrine.)
narrow waters, some of the essentials of night combat require re-examination if they are to be included as doctrine.
1. It is intended that submarine squadrons, submarine divisions, and individual submarines not included in 6 Fleet will be trained on the basis of unified concepts.
Force” refers to suitable cruisers, converted cruisers and aircraft carriers, the chief function of which is scouting and which are added for such operations as destruction of sea traffic.
At present base air forces operate in separate areas and on occasion place elements under command of another. In the future, however, they will operate as the Combined Base Air Force. Further, since units of all air fleets and air flotillas will be increasingly placed under the command of commanding officers of other forces, it is necessary to establish Combined Base Air Force doctrine, standard procedure (YOMU JUNSOKU) and doctrine suitable to all air flotillas, KOKUTAI, HIKOTAI and similar forces.
This basic organization is established in accordance with the above. To carry out and direct those provisions and the training relative to them is the responsibility of the base air force commander who is the senior commanding officer. He may make suitable commanding officers responsible for any necessary work as he sees fit.
Copies of his memorandum will be sent to all squadrons, flotilla and division headquarters and to all base headquarters.
1944
After taking over as Commander Combined Fleet Admiral Toyoda issued a series of orders. Most were the usual type but one is of interest since he moved their tactical/administrative table of organization formats towards those used by the U.S. Navy; not quite however. One notices immediately that unlike the USN Task Force formats, where units could be plugged into a task force table of organization without reference to their administrative assignment here the administrative assignment follows the squadron, ship, etc.
COMBINED FLEET ULTRASECRET STANDING ORDER 20
Division of Fleets of the Combined Fleet
COMBINED FLEET
OYODO Unit #15
FIRST AIR FLEET
Air Flot 61 Unit # 1001 Air Flot 22 Unit # 1002 Air Flot 23 Unit # 1003 Air Flot 26 Unit # 1006
CinC First Air Fleet will determine fleet division for remaining surface forces attached to First Air Fleet using Unit # 1061 to 1100
FIRST MOBILE FLEET
Second Fleet CruDiv 4 Unit # 24 CruDiv 5 Unit # 25 CruDiv 7 Unit # 27 Bat Div 1 Unit # 21 Bat Div 3 Unit # 23 Des Ron 2 Unit # 22
Third Fleet Car Div 1 Unit # 31 Car Div 2 Unit # 32 Car Div 3 Unit # 33 Des Div 10 Unit # 37 MOGAMI Unit # 38
CinC 3rd Fleet will determine fleet division for remaining surface forces attached to 3rd Fleet using Unit # 35 to 36 and 2351 to 2400
CinC FIRST MOBILE FLEET will determine fleet division for remaining surface forces attached to First Mobile Fleet using Unit #2301 to 2350.
Sixth Fleet Sub Ron 7 Unit # 61 Sub Ron 8 Unit # 62 Sub Ron 11 Unit # 63
CinC 6th Fleet will determine fleet division for remaining surface forces attached to 6th Fleet.
Northeast Area Fleet Fifth Fleet
Cru Div 21 Unit # 51 Des Ron 1 Unit # 55
CinC 5th Fleet will determine fleet division for remaining surface forces attached to 5th Fleet using Unit # 2551 to 2600
12th Air Fleet
Air Flot 27 Unit # 1227 Air Flot 51 Unit # 1251
CinC 12th Air Fleet will determine fleet division for remaining surface forces attached to 12th Air Fleet.
(under direct command of Northeast Area Fleet)
Cru Div 22 Unit # 52 Kurile Island Area Base Unit # 57
Northeast Area Fleet will determine fleet division for remaining surface forces attached to Northeast Area Fleet.
Remaining portions omitted here.
A practical application of Standing Order 20 was Combined Fleet Ultrasecret Operation Order 79 issued 30 May to become effective 1 August (portions are omitted see below item 29).
27. Revised Allocation Third Phase Operations: Combined Fleet 28. OpOrd #78 Assignment of supply forces 29. Regulations for Identification of Combined Fleet Airplanes
REGULATIONS FOR IDENTIFICATION OF COMBINED FLEET AIRPLANES
. . .
COMBINED FLEET
Notes: 1. For unit (ship) names the ship (sequence) number will be added to the two digits of the unit code numbers given adjacent to the unit number raising the number of digits to three (When there is no need to add the ship number 0 will be added. 2. Airplane numbers will be sequential. 3. For example OYODO # 1 airplane will be 150-01 etc.
COMBINED FLEET
OYODO Unit # 15 color: Yellow
2nd Fleet (color White or Blue) Bat Div 1 Unit # 21 Bat Div 3 Unit # 23 Cru Div 4 Unit # 24 Cru Div 5 Unit # 25 Cru Div 7 Unit # 27 Des Ron 2 Unit # 22
3rd Fleet (color Red or Yellow)
Des Div 10 Unit # 37 MOGAMI Unit # 38
(note: the Naval Air Groups were separate entities and numbered accordingly)
Balance omitted.
Note: For example battleship YAMATO was unit 211 (2nd Fleet; 1st Division; #1 ship) and its planes would be numbered 211-01 etc.
30. Standing Order #21 Identification codes for identification of Friendly Forces, dated 11 July 1944. 31. Special Order #42 Combined Fleet Regulations re Patrol Codes, dated 22 July 1944. 32. OpOrd #82 Regulations for Base Air Force Air Patrols, dated 1 August 1944. 33. OpOrd #83 Revises distribution list for Outline of Combined Fleet Operations. 34. OpOrd #84 Allocation of Forces revised for Third Phase Operations 1 August 1944. 35. OpOrd #85 Distribution List of Outline of Operations dated 4 August 1944. 36. OpOrd #86 Air Combat Regulations for Sho Operations issued 4 August 1944. 37. OpOrd #87 Outline for Advanced Expeditionary Force Sho 38. OpOrd #90 Revision of Combined Fleet Operations dated 24 August 1944. 39. OpOrd #91 Revisions of OpOrd issued 24 August 1944. 40. OpOrd #92 Joint Operations of Naval Forces dated 24 August 1944. 41. OpOrd #94 Additional Patrol Sectors Combined Fleet Air Forces dated 27 August 1944. 42. OpOrd #96 Amphibious Counterattacks Sho dated 1 September 1944. 43. Memorandum 27 on Operations Orders revised distribution list dated 1 September 1944.
This list is certainly incomplete, but does show how bureaucratic navies are. The number of revisions to various standing orders, distribution lists, etc promulgated can be staggering to the uninitiated. It illustrates how much preparation is needed to do what appears to be the simpliest tasks.
After taking over as Commander Combined Fleet Admiral Toyoda issued a series of orders. Most were the usual type but one is of interest since he moved their tactical/administrative table of organization formats towards those used by the U.S. Navy; not quite however. One notices immediately that unlike the USN Task Force formats, where units could be plugged into a task force table of organization without reference to their administrative assignment here the administrative assignment follows the squadron, ship, etc.
COMBINED FLEET ULTRASECRET STANDING ORDER 20
Division of Fleets of the Combined Fleet
COMBINED FLEET
OYODO Unit #15
FIRST AIR FLEET
Air Flot 61 Unit # 1001 Air Flot 22 Unit # 1002 Air Flot 23 Unit # 1003 Air Flot 26 Unit # 1006
CinC First Air Fleet will determine fleet division for remaining surface forces attached to First Air Fleet using Unit # 1061 to 1100
FIRST MOBILE FLEET
Second Fleet CruDiv 4 Unit # 24 CruDiv 5 Unit # 25 CruDiv 7 Unit # 27 Bat Div 1 Unit # 21 Bat Div 3 Unit # 23 Des Ron 2 Unit # 22
Third Fleet Car Div 1 Unit # 31 Car Div 2 Unit # 32 Car Div 3 Unit # 33 Des Div 10 Unit # 37 MOGAMI Unit # 38
CinC 3rd Fleet will determine fleet division for remaining surface forces attached to 3rd Fleet using Unit # 35 to 36 and 2351 to 2400
CinC FIRST MOBILE FLEET will determine fleet division for remaining surface forces attached to First Mobile Fleet using Unit #2301 to 2350.
Sixth Fleet Sub Ron 7 Unit # 61 Sub Ron 8 Unit # 62 Sub Ron 11 Unit # 63
CinC 6th Fleet will determine fleet division for remaining surface forces attached to 6th Fleet.
Northeast Area Fleet Fifth Fleet
Cru Div 21 Unit # 51 Des Ron 1 Unit # 55
CinC 5th Fleet will determine fleet division for remaining surface forces attached to 5th Fleet using Unit # 2551 to 2600
12th Air Fleet
Air Flot 27 Unit # 1227 Air Flot 51 Unit # 1251
CinC 12th Air Fleet will determine fleet division for remaining surface forces attached to 12th Air Fleet.
(under direct command of Northeast Area Fleet)
Cru Div 22 Unit # 52 Kurile Island Area Base Unit # 57
Northeast Area Fleet will determine fleet division for remaining surface forces attached to Northeast Area Fleet.
Remaining portions omitted here.
A practical application of Standing Order 20 was Combined Fleet Ultrasecret Operation Order 79 issued 30 May to become effective 1 August (portions are omitted see below item 29).
27. Revised Allocation Third Phase Operations: Combined Fleet 28. OpOrd #78 Assignment of supply forces 29. Regulations for Identification of Combined Fleet Airplanes
REGULATIONS FOR IDENTIFICATION OF COMBINED FLEET AIRPLANES
. . .
COMBINED FLEET
Notes: 1. For unit (ship) names the ship (sequence) number will be added to the two digits of the unit code numbers given adjacent to the unit number raising the number of digits to three (When there is no need to add the ship number 0 will be added. 2. Airplane numbers will be sequential. 3. For example OYODO # 1 airplane will be 150-01 etc.
COMBINED FLEET
OYODO Unit # 15 color: Yellow
2nd Fleet (color White or Blue) Bat Div 1 Unit # 21 Bat Div 3 Unit # 23 Cru Div 4 Unit # 24 Cru Div 5 Unit # 25 Cru Div 7 Unit # 27 Des Ron 2 Unit # 22
3rd Fleet (color Red or Yellow)
Des Div 10 Unit # 37 MOGAMI Unit # 38
(note: the Naval Air Groups were separate entities and numbered accordingly)
Balance omitted.
Note: For example battleship YAMATO was unit 211 (2nd Fleet; 1st Division; #1 ship) and its planes would be numbered 211-01 etc.
30. Standing Order #21 Identification codes for identification of Friendly Forces, dated 11 July 1944. 31. Special Order #42 Combined Fleet Regulations re Patrol Codes, dated 22 July 1944. 32. OpOrd #82 Regulations for Base Air Force Air Patrols, dated 1 August 1944. 33. OpOrd #83 Revises distribution list for Outline of Combined Fleet Operations. 34. OpOrd #84 Allocation of Forces revised for Third Phase Operations 1 August 1944. 35. OpOrd #85 Distribution List of Outline of Operations dated 4 August 1944. 36. OpOrd #86 Air Combat Regulations for Sho Operations issued 4 August 1944. 37. OpOrd #87 Outline for Advanced Expeditionary Force Sho 38. OpOrd #90 Revision of Combined Fleet Operations dated 24 August 1944. 39. OpOrd #91 Revisions of OpOrd issued 24 August 1944. 40. OpOrd #92 Joint Operations of Naval Forces dated 24 August 1944. 41. OpOrd #94 Additional Patrol Sectors Combined Fleet Air Forces dated 27 August 1944. 42. OpOrd #96 Amphibious Counterattacks Sho dated 1 September 1944. 43. Memorandum 27 on Operations Orders revised distribution list dated 1 September 1944.
This list is certainly incomplete, but does show how bureaucratic navies are. The number of revisions to various standing orders, distribution lists, etc promulgated can be staggering to the uninitiated. It illustrates how much preparation is needed to do what appears to be the simpliest tasks.
9 Destroyer Doctrine and Procedure < xml="true" ns="urn:schemas-microsoft-com:office:office" prefix="o" namespace=""> At the beginning of the Pacific War the Japanese Destroyer force was among the best in the world. Though they did not fight the battles they had trained for their doctrine and procedure served them well for nearly two years. In a series of intense actions they matched and often overmatched their principal adversary, the U. S. Navy. By the end of 1943 the U. S. Navy had caught and in most respects passed the Japanese Navy in the skills that had served the Japanese so well.
The rewrite of Japanese Destroyer Doctrine and Procedure here was published by Admiral Kurita’s Second Fleet staff in December 1943. It is still a document that anticipates a big gun/torpedo action much like those practiced by both navies between the wars.
DESTROYER DOCTRINE
General Principles This Doctrine is based on Combined Fleet Doctrine, Diversion Attack Force Doctrine, Mobile Force Doctrine and Night Operations Force Doctrine.
Alert, Approach and Scouting
General Rules: When in a condition of alert ships will observe the following:
Orders for Cruising under Alert (Keikai Koko) When a destroyer squadron is proceeding to attack independently it will take precautions against enemy aircraft and submarines and prepare to meet enemy surface forces. The usual zig zaging will be carried out except in especially poor visibility. The orders for cruising under alert and their application are as follows:
Order of Cruising Under Alert 1
Screening Unit
C C
D
C C
A
B
Notes: A=3km; B=1km; C=2km; D=3km
The units will take station on the flank on which they are proceeding. In the screening unit formation, changes will be possible except with D This order will usually be used during the day.
Order of Cruising Under Alert 2 E
B
D
C
A
B
Notes: A=3km; B=1km; C=2km; D=5km; E=5km This is a night cruising order D & E will be maintained as indicated in the order. The disposition of strength will be fixed by the commanding officer of the screening unit. The units will take up station on the flank on which they are proceeding.
Order of Cruising Under Alert 3
Notes: A=3km; B=3km; C=2km
In the absence of special orders the stations will be as follows:
Notes: If any of the units are lacking the required number of ships positions 13, 14, 15 or 16 will be omitted. The angle of station may be change, which change will be reported. This is a day order.
Order of Cruising Under Alert 4
Same as 3 except that left is interchanged with right.
Entering and < xml="true" ns="urn:schemas-microsoft-com:office:smarttags" prefix="st1" namespace="">Leaving Harbor will be done quickly and secretly while keeping a strict lookout for submarines, mine laying airplanes and torpedo boats. Paravanes will be streamed. In the event magnetic mines are suspected waters of less than 80 meters should be avoided. Areas suspected of enemy submarine activity (typically within 100 miles of the harbor mouth) a speed of 20 knots or more should be maintained.
Temporary Anchorage in Enemy Waters. In such cases strict alert should be maintained. Selection of such anchorages are determined using the following criteria: Anchorage in group or separately Security and Patrolling Adherence to reconnaissance plan Engine readiness Tactics at time of enemy attack Defense When anchoring where there is danger from enemy mines degaussing will be used even when at anchor. If necessary sweeping will be carried out.
Approach
Parallel lines with the flagship at the head will be normally used as the order of approach.
Order of Approach 1
A=1km; B=1km; C=4km. May be lengthened if situation merits. Stationing the flagship at the center of both units will be an alternate method.
Order of Approach 2: Same as 1 except the flagship will be at the head of the left column.
Order of Approach 3:
A=5km; B=5km. This is a night order of approach
Scouting: Scouting will be the primary responsibility of airplanes. Scouting by ships will be conducted in accordance with the following:
Scouting Disposition Notes: Each unit will maintain its relative position and proceed in the indicated direction at the designated speed. The type of scouting disposition, base course, speed and interval will be ordered when scouting is to begin. Unless otherwise ordered a will be10 km and the base course and speed will be the same as at the time action begins. The line of scouting dispositions will be at right angles to the course being followed. Unless otherwise ordered the flagship will be the guide. The flank on which a unit will be stationed is determined by its station at the time the maneuver begins. In case of doubt, special orders will be issued. The station of each unit will front on the base course and will be indicated by unit name in order from the right.
Combat policy in day action is to close in on the enemy and destroy it. At night it is to destroy the enemy in one stroke. In task force operations assist in developing the fighting power of the raiding air groups
Combat Methods
Day Engagements Fleet Actions Outline Strikes by Groups (Shudan) Signal:
Strikes by Deployment will be conducted as follows: Signal:
Day Engagements with Enemy Forces Outline
Order of Battle
Night engagements Night engagements in open sea Outline Tracking Destruction of enemy delaying force
Attack Dispositions
Dispositions 1-4 provide for alternate dispositions by exchanging left for right. Also note that the general method for each disposition is set forth. The form will not be inflexible in any case. Operations will immediately correspond to changes in the situation.
Night Engagements with Enemy Light Forces Night Operations in Narrow Waters
COMBAT REGULATIONS Torpedo Action Standard Plan for Firing Day (Decisive Battle):
Depth Setting: Capital Ships: 6m (Cruisers sometimes use second setting; Capital Ships and Aircraft Carriers; 5m; Cruisers and aircraft carriers; 4m; Destroyers 3m
Point of Aim: Center ship of unit under attack (if there are four ships-Second ship.
Night (during attack)
Note: Depth setting: same as day settings.
Secret Torpedo Action: Unless specifically ordered Ko will be ordered.
Notes to Secret Torpedo Action Depth Setting: Against Capital Ships and a group of cruisers 5m; Against groups of cruisers 4m; Against groups of cruisers and destroyers 3m. Point of Aim: In firing, the following will be used as standard or basis for direction; Silhouette or searchlights of enemy ship, Parachute flares dropped by friendly airplanes, Electric ranging and direction by friendly airplanes. Disposition According to Situation: The various units will be chosen depending on whether they are proceeding directly or approaching. When Forward of the beam the unit next ahead (Sec 1) will proceed directly and the following unit (Sec 2) will then approach. When abaft the beam, the opposite procedure will be followed. Number of Fired Torpedoes: Half of full firing line.
Gunnery Engagements
*Sketch examples below:
DESTROYER PROCEDURE
The standard amount of time consumed increasing or decreasing formation speed is as follows:
*There is some overlap beginning at Full Speed/Battle Speed 1 thus the opening at BS4.
This standard is the time it takes the main shaft to attain the number of RPM for a specified speed. This standard also applies to the amount of time required to increase or decrease the speed of a warship cruising independently.
[1] Torpedo Speed 1 is 49 knots/range 20,000 meters; Torpedo Speed 2 is 36 knots/range 40,000 meters.
10 (a). CarDiv 4 Doctrine
Carrier Division Four Doctrine: Since this is the only pre 1943 doctrine in the NACHI find and one that pertains to Japanese carriers in 1941-2 it is worth setting out in full. A brief summary of Carrier Division Four operations is also in order.
Carrier Division Four (Dai Shi Koku Sentai 4sf) was organized in April 1941 when the carriers were placed under one administrative organization, First Air Fleet (Dai Ichi Koku Kantai). At the time it was organized Carrier Division Four consisted of carrier RYUJO and her destroyer screen. From April until early November RYUJO operated in the central Pacific returning to Kure in the home islands on November 10, 1941. On November 27 while still in Kure Admiral Kakuta, commander Carrier Division Four issued Ultrasecret Standing Order 20, Carrier Division Four Doctrine. This was the same day the Pearl Harbor Strike Force, First Mobile Force (Dai Ichi Kido Butai or 1KdB) departed Japanese home waters for the attack which would open hostilities between the U. S. and Japan. One hundred copies were issued with one going to NACHI. When operating as a tactical unit 4sf would become Second Mobile Force (Dai Ni Kido Butai or 2KdB).
During this period light carrier SHOHO entered service. She was attached to 4sf on December 22, 1941 remaining in home waters working up until early February.
While SHOHO worked up RYUJO was very active supporting the Philippine invasion from the outbreak of the war until December 26. In early January she operated out of Camrhan Bay in support of the Malay operation. In February she was assigned to the forces attacking the Netherlands East Indies. In March she continued supporting operations in the Malay and Burma areas, operating there until April when she returned to Japan for a drydock period before AL (Aleutians).
During this period SHOHO moved between Truk and the Empire before participating in Operation MO when she was lost in the Battle of Coral Sea. At no time during her period of service did SHOHO operate with RYUJO as a tactical unit.
On May 3, 1942 after her commissioning carrier JUNYO joined 4sf, just in time for Operation AL. This was the one time 4sf had two carriers.
Following the Midway disaster First Air Fleet was disbanded and the carrier divisions reduced to two, both being assigned to Third Fleet (Dai San Kantai). On July 14, 1942 4sf was disbanded and its two ships joined JUNYO’s sister HIYO to form Carrier Division Two (Dai Ni Koku Sentai 2sf)[1].
In 1944 Carrier Division 4 was reformed, but that formation had nothing to do with the 1941-2 version.
Here follows the bulk of Carrier Division 4 Doctrine:
Carrier Division 4 (4sf) Doctrine, 27 November 1941
I. General Principles In this Doctrine are set forth the plans and policies to be adopted by CarDiv 4 before, during and after combat and those matters to which each ship will conform. Each commanding officer is expected to do his utmost to conform to this doctrine and to apply the instructions contained in the “Naval Combat Regulations”[2] and in the various manuals.
II. Security
Notes: Cruising Order 5 (6): In absence of special order D will be equal to the limit of visibility. The destroyer will maintain especially strict security to starboard (port). Cruising Order 7 (8): In the absence of special order D will be equal to the limit of visibility. The destroyer will maintain especially strict security to the starboard (port) quarter.
Outline of Patrol Operations: Duration of one patrol will be three hours Datum Point “O” will be fixed by special order In the absence of special orders the base course will be the course at the time In the absence of special orders the patrol range “D”, interval between patrol lines “b” and measurement “d” will be as indicated in the diagram. Each airplane will patrol by following the movements of the diagram and reversing them within the prescribed time. The altitude of the airplane will be determined by the airplane (unit) commander When enemy submarines are being neutralized or enemy ships and boats tracked, the duration of the patrol will be four hours. Special orders may assign two airplanes to each patrol line
2. Direct Antisubmarine Escort
Duration of one patrol will be approximately three hours, relief will be made at a designated position. Standard altitude will be 300-500 meters The airplane (unit) commander may so reduce his range from the ship (or ships) being directly escorted that he will be within sight when visibility is reduced. The movements indicated in the diagram will be based on the ship (ships) When enemy submarines are detected they will be attacked and neutralized. At the same time the prescribed report will be sent to lead the direct escort destroyers to the spot.[4]
Outline of Patrol Operations Duration of one Patrol will normally be three hours In the absence of special orders the rear ship of the group will be the base ship In the absence of special orders the course at the time will be the base course The patrol will attack and sink enemy submarines, in accordance with movements indicated in the diagram.[5]
Outline of Operations: Duration of one patrol will be two hours. The succeeding patrol will automatically be first group (or by special orders the second group) of alerted airplanes Relief of each patrol will be at assigned positions Security area: generally within the limits of the whole field of vision over the ship (or group of ships) being directly escorted. As a basic rule the, the ship command of the high altitude direct escort will be aboard the carrier. Exceptions will require a special order The high altitude direct escort will patrol in fighter unit formation. The commanding officer may alter the altitude to suit the ceiling and field of vision.[6]
In the orders to the anti aircraft patrol planes, the assigned areas, the take off time of the airplanes, the duration of the patrol and the range of the patrol “D” will specified.
Patrol Outline The patrol aircraft will move around the circumference of the assigned area, keeping a sharp watch for enemy airplanes and sending in patrol reports (warnings) As a general rule one plane will be assigned to each sector Patrol altitude will be 3,000 to 4,000 meters In the absence of special orders “D” will be 20km In going back and forth between assigned points, anti submarine patrol also will be carried out.[7]
III. Search, Reconnaissance and Tracking
Outline for Execution of Search By special order the basic search line begins at datum point (0), Range is “D”, lateral distance is “d”, angle is “o”, area is (1) Normally one airplane is used in the search line. If two or more airplanes are assigned a special order is required. In the absence of special orders each search plane will return to the datum point according to the outline of movements in the diagram. When the number of search lines is greater than the number on the diagrams, each side will be added to successively and when less than the number on the diagram the lines in excess will be deleted successively.[8]
IV. Combat
The main object will be to destroy the enemy forces in a particular area immediately with all of our power. To this end the greatest possible mobility will be employed, and the airplanes available will be used extensively and aggressively. Friendly forces will be protected by keeping a strict alert against airplanes and submarines and by seizing the initiative and destroying those that are discovered. The particular vulnerability of aircraft carriers will be kept in mind. The policy is that aircraft carriers will not engage in combat with surface ships except when especially necessary or under especially favorable conditions. While aircraft carriers are escaping from surface ships, the latter will be destroyed by airplanes and destroyers. The destroyers will place themselves quickly between the aircraft carrier and the enemy concealing the carrier, and at a favorable opportunity, will counterattack.
This command will order air combat. Although the outline of organization, object of attack, weapons to be used and movements will be ordered by this command when an attack unit is sent out, the attack will be executed under the command of the attack unit commander. In an air attack complete success will be attained by greatly shortening combat distance and using the time gained to make sudden and repeated attacks. In an attack when resistance by airplanes is expected, the fundamental policy is to gain control of the air by use of fighter planes and attack under their protection. Nevertheless, in certain cases, attack plane units only will attack on moonlit nights at dawn and at dusk. The principal object of the high altitude direct escort unit will be to engage raiding airplanes in combat outside the range of anti aircraft fire and before they attack. The attack must first be concentrated on the airplane of the enemy commanding officer (the guide airplane). After the enemy attack maneuvers are disorganized, his airplanes will be destroyed one after another. Our direct escort dispositions must not be weakened by over concentration of strength on one objective or sustained pursuit of airplanes after an attack.
The attack unit will be organized as follows:
Command to be fixed by the captain of the aircraft carrier Full Strength is the number of airplanes available at present but will not exceed the number normally used. Organization for cases other than those listed will be given by special order.
Standard of weapons used in attack will be as follows:
Bomb notes: the weight and penetration characteristics are from the Naval Technical Mission to Japan Report O-23 “Japanese Bombs” and are not in the NACHI find. Such items as optimum altitude for dropping etc are not in the report.
Torpedoes: Torpedoes will be used against cruisers and above according to special orders. Torpedo Data: Fixed speed 42 knots Fixed depth: Battleships 6 meters, Cruisers 3.5 meters
Day Gunnery Engagements Gunnery engagements will be opened at the most extreme range promising good results. Although the main function of the flagship normally is considered to be the directing and ordering of fire, this will be left to the discretion of the individual ship captains where rapid antiaircraft or anti submarine fire is necessary at a time when the flagship is itself firing. Firing by destroyers will be left to the discretion of the commanding officers.
Night Gunnery Engagements In case enemy ships, boats or airplanes are discovered at night, normally they will be avoided insofar as possible. However under certain circumstances an attack with the aid of illumination will be made. Normally illumination and gunfire will be executed by order, but, when speed is necessary, it will be left to the discretion of the ship captains (commanders).
Torpedo engagements, except those carried out by airplanes, will be carried out by destroyers Standard Plan for Destroyer Torpedo Attacks Torpedo Firing Data
Destroyers will carry out depth charging.
V. Procedure
Battle speeds for a given unit will be as follows: Battle Speed 1=18 knots Battle Speed 2=20 knots Battle Speed 3=22 knots Battle Speed 4=24 knots Battle Speed 5=28 knots Maximum Battle Speed=Maximum speed of which each ship is (unit) is capable.
Normally smoke screens will be laid by destroyers. Sometimes they will be laid by the carriers themselves. The laying of smoke screens by destroyers will be left to the discretion of the commanding officer of the destroyer division. Normally the laying of a smoke screen by a carrier will require special orders.
Panel signals from aboard ship to Direct Escort Planes
Notes: 1. Panels will be made of sailcloth or thin boards, white in color and will be divided into two kinds; long and short, and standardized as follows: Long; width 1 meter, length 4 meters. Short; width 1 meter, length 2 meters 2. Positions for stretching signal panels: Aircraft carriers; Flight Deck, Others ships and boats, on the deck forward of the forward bridge or on a gun turret. 3. With signal panels which indicate the direction of enemy airplanes the head of the letter T will be pointed in the direction of the enemy airplanes.
This doctrine is the only one recovered from NACHI that predates the Solomons campaign. It also was issued pre-radar. At that time the carrier was recognized as a weapon of powerful offensive capabilities, yet extraordinarily weak defensively. Both its defense and offense were the responsibility of its air group. The Japanese solution to this problem was to concentrate its big carriers into a single unit, first of four ships and, by the time of Pearl Harbor, six. By doing this they were able to allocate sufficient resources to all of the tasks outlined in this doctrine. Certainly one or two small carriers could not match their larger sisters. In fact this doctrine when matched with the resources available to execute it goes far to illustrate the genius of the decision to concentrate their big carriers. It also illustrates the need to keep that concentration. To do otherwise meant corners would be cut. If an objective was not worth committing all six carriers none of them should be committed. Of course the smaller force could conduct operations where the larger group was not needed. To carry out all of the tasks set out herein would require: Patrol of route of advance; 1-3 VT, Direct antisubmarine escort; 1-4 VT, Security against trailing submarines; 1-2 VT, High altitude direct escort; 3-9 VF, Anti aircraft patrol; 8 VT, Air search; 2-4 VT, Attack units; 3 or more VT and 9 or more VF. With the exception of air search these figures would be very similar for the large carriers, but spread among the six ships. For contemporary Japanese tables for the larger ships see the treatment of Pearl Harbor in “Campaigns of the Pacific War”, pp. 23-24.
It should not be surprising that U. S. Navy doctrine was quite similar.
Note: Air Groups on board Carrier Division 4 ships December 1941-June 1942:
RYUJO: December 1941: 16 VF; 18 VT=34 total January-March 1942: 22 VF; 16 VT=38 total April 1942: 16 VF; 20 VT=36 total May 1942: 16 VF; 21 VT=37 total June 1942: 16 VF; 20 VT=36 total SHOHO January-May 1942: 16 VF; 12 VT=28 total JUNYO June 1942: 16 VF; 24 VB=40 total Note: some or all of RYUJO and SHOHO VF were A5M during part of this period. The other VF were A6M , the VB D3A and the VT B5N.
[1]This brief outline of the operations of 4sf is from several sources: Imperial Japanese Navy in World War II, a graphic presentation of the Japanese Naval Organization and List of Combatant and Non-Combatant Vessels Lost or Damaged in the War, Japanese Monograph 116; Tabular Records of Movements of Japanese warships found on the Nihon Kaigun website, http://www.combinedfleet.com and various popular histories. [2] Not recovered in NACHI group. [3] USF 77 CURRENT TACTICAL ORDERS, AIRCRAFT CARRIERS U.S. FLEET (3-41) contains provision for four plane guard stations: Flight stations, night operations, day operations (high visibility) and day operations (low visibility). Otherwise they are not substantially different from the Japanese method. [4] U. S. practice was quite similar. See USF 74 (Revised) Current Tactical Orders Carrier Aircraft (3-41) section 1-536: Intermediate air patrol is defined as protection against enemy submarines, preventing them from gaining favorable attack position. 2-3 plane units search 30 degree sub sectors 60 degrees either side of base course (4X3 aircraft). The depth of the search is 40 miles out and flown at no greater height than 2500 feet. Both navies working assumption seems to be based on limiting lines of approach, that is to say, if the submarine isn’t somewhere between 45 degrees and 60 degrees of the carrier’s base course, assuming the carrier is making good speed, it will not be able to get into firing position. In both cases this is good doctrine with the American doctrine being somewhat more conservative . [5] No American equivalent. When the threat from a trailing submarine is set against available resources the American practice makes more sense. [6] USF 74 section 1-539 establishes two types of “Combat Patrols” (later Combat Air Patrol); 1. patrol of 4-6 VF, “if enemy bombing attack are anticipated it may be necessary to retain the entire fighter strength as one patrol relying on aerial pickets to report enemy aircraft in sufficient time for the patrol to engage the bombers before they have delivered their attack (pre radar 3-41). 2. To deny enemy observation 3-4 VF patrol to thwart enemy VS. Altitude 7,000-10,000 feet in both cases. [7] USF 74 section 1-535 describes Outer Air Patrol as 3 plane units flying along chord of sub arcs of a 20 n. mile circle, “only that part of the circle from which attack is expected normally will be patrolled.” [8] See USF 74 section 2-101 et seq. There is little difference between the two navies on this subject. [9] USF 77 section 302. Airplanes may be ordered to assume a condition of readiness irrespective of that under which the parent ship operates. Condition 1: Airplanes kept warmed up, Flight personnel in flight clothing, in possession of latest available information of the tactical situation. Personnel and equipment ready to permit launching on 10 minutes notice. Condition 2: Personnel and equipment in readiness to permit launching on 20 minutes notice. Condition 3: Personnel and equipment in readiness to permit launching on 30 minutes notice.
10 (b) Cruiser Doctrine
Tactics: The basic evolution unit is the Cruiser Division (usually 8” gun ships) designated by the Roman letter/Arabic number combination which corresponds with its division number; i.e. 4S=Cruiser Division 4.[1] Standard distance for cruisers is 800m. Speed signals with acceleration tables for heavy cruisers are as follows:
*BS=Battle Speed
General Doctrine: The standard cruiser division combat formation is the single column with the flagship in the lead though a fine quarter line may be used.
Cruisers are to provide covering gunfire for destroyers in torpedo attacks and when enemy battleships or cruisers are present launch their own torpedoes against those major units. They are to use their guns only against enemy light forces, though the use of torpedoes against enemy light cruisers and destroyers is not prohibited if the tactical situation indicates it is proper.
Day Action: The types of Day Action are:
Notes to Day Action: An engagement on same course will be called Method 1; opposite course Method 2. No special signal will be issued for Method 1.
The cruiser forces are responsible for screening the battle force and reporting enemy dispositions to facilitate the deployment of the battle force and exploiting torpedo opportunities. If the enemy battle line is observed deploying a large spread of torpedoes should be fired across the enemy line of advance to confuse or destroy the enemy battle line early in the action.[2]
Surface Gunnery: Night: Gunfire is to be opened at 18,000 meters when star shells are used for illumination while 10,000 meters is opening range when searchlights are used (12,000 meters in the South Seas).
Anti Aircraft Gunnery: Anti Aircraft cannon and heavy machine guns are to be used in surface engagements at the discretion of the ship’s captain. Standard opening ranges for anti aircraft weapons are: Cannons (12.7cm, 12 cm, 10 cm, 7.6 cm) 10,000 meters (day), 7,000 meters (night) Machine Guns (25mm, 13mm, 7.7mm) 3,500 meters
Torpedoes: The center ship in the enemy’s lead battleship division is the point of aim for torpedo attacks. When an enemy division contains two or four units the number two ship will be chosen as point of aim. Torpedoes will be set at 6 meters depth for battleships and large carriers; 5 meters for heavy cruisers and medium carriers; while 3-4 meters will be used against mixed formations. The optimum ranges for firing torpedoes is considered 5 kilometers (3 miles). This, of course, applies to standard attacks. Generally #2 torpedo speed (36 knots) will be used for day or night fighting though division or ship commanders may make appropriate speed changes depending on the tactical situation. Concentrated salvos or spread salvos may be used depending on the tactical situation.
Single line ahead or a quarter line (line of bearing) of less than 30 degrees are the preferred torpedo firing formations. In quarter line care is to be taken to avoid torpedoes of ships ahead in the formation.
The type 93 torpedo allows cruisers to conduct Long Range Concealed Attacks. Air spotting and lookout information is to be used to insure adequate information for long range attacks. Spare torpedoes from the disengaged side are to be used as first reloads thus giving the tubes on the engaged side three shots per tube. Torpedoes are to be used liberally. In the advanced phases of a battle, the practice will be to approach as close to the enemy as possible and to fire continuously at short range without giving the enemy a chance to evade the attack. In all cases, however continuous firing will be by special orders.
In Night Long Range Concealed Attacks firing will be at the limit of the field of vision and all aids to fire control will be exploited (star shells, parachute flares, aircraft dropped float flares, radio direction finders and radar) so firing beyond the field of vision can be accomplished. Ideally concealed attacks will be timed so the torpedoes arrive at the time night attacking destroyers arrive at their firing position. In carrying out concealed joint torpedo actions from both flanks of the enemy main force while in separate contact with both quarters of the enemy, the time of firing will be designated and normally the basic course and speed of the enemy will be given by order. In order to make firing at the designated time possible, each ship will proceed toward the enemy and make timely position reports. All ships will maintain close liaison, get on the target and fire at the time designated. The angle of fire will be selected to cover the direct advance or a 40 degree evasive turn by the enemy. Concealed firing carried out in cooperation with friendly cruiser division(s) in contact on the opposite flank will follow an outline set forth above.
Aircraft: Cruisers (and battleship) based aircraft are tactically assigned to the Cruiser Division Commander while they are the administrative responsibility of the individual ship. In operations the aircraft on the windward catapult will be launched first. Unless otherwise ordered aircraft will return to their ship upon completion of their mission, conducting a short ASW search before recovery. In special cases they might be put ashore at a friendly base after their mission is completed.
The To get a full picture of Japanese cruiser doctrine from the NACHI documents Combined Fleet Doctrine, Night Operations Doctrine and Diversion Attack Force Doctrine must be read in conjunction with this paper.
The greatest difference between Japanese cruiser doctrine and that of the U.S. Navy and Royal Navy is in the area of night fighting. The substantial difference can be summed up in this quote from the Royal Navy’s Fighting Instructions; “’Stationing of 8 inch Cruisers at Night’. The employment of 8 inch cruisers at night is a difficult problem. They are important ships whose armament is not specially suited for dealing with light craft at night, and they are large and unhandy targets vulnerable to both gun and torpedo. If sufficient screening forces are available without them, the 8 inch cruisers should normally be stationed in the line of the heavy ships. If, however the fleet is short of screening forces, the 8 inch cruisers may be stationed in pairs on the quarter of the battle fleet since they can generally move out counter attack without the necessity for large alterations of course.” The reason for this wide variance can be explained in one word: torpedoes. While the USN and RN were offloading torpedoes from their 8 inch gunned cruisers at the same time the IJN was enhancing the torpedo armament of theirs. The torpedo armament of Japanese cruisers by the beginning of the war was huge: MYOKO and TAKAO classes 16x24” tubes and 8 reloads. MOGAMI and TONE classes 12x24” tubes and 12 reloads. All were capable of firing the type 93 long range torpedo. The Japanese considered these ships capital ship killers. [1] Technically this is 4S doctrine. By virtue of their assignment to Second Fleet (Diversion Attack Force) the other Second Fleet Cruisers were bound by it. Memo 13 of August 1943 sets this out: “Accordingly, all cruiser divisions . . . of the Imperial Navy will establish their doctrine . . . in accordance with the doctrine established by the Diversion Attack Force” (see chapter 8 for that memo).In 1944 there were three cruiser divisions assigned to Second Fleet: 4S (ATAGO, CHOKAI, MAYA, TAKAO), 5S (MYOKO, HAGURO) and 7S (SUZUYA, KUMANO, TONE, CHIKUMA). MOGAMI was a special duty ship assigned to Third Fleet. Cruiser divisions assigned to area fleets were: 14S NAKA, ISUZU(deactivated March 1944) 16S ASHIGARA to February 25; AOBA from February 25 to November 5, OI, KITAKAMI, KATORI, KINU. 21S NACHI, ASHIGARA (after February 25), TAMA, KISO. [2] For comparisons see USF 20 CURRENT TACTICAL ORDERS CRUISERS, US FLEET, USF 21 CURRENT DOCTRINE CRUISERS US FLEET and, for the Royal Navy, THE FIGHTING INSTRUCTIONS, 1939. The latter can be found on line at the HMS HOOD ASSOCIATION [3] Cruiser (and to a lesser extent battleship) floatplanes played a vital role in long range reconnaissance for the Japanese Navy. As completed the TONE class ships had enhanced aircraft handling facilities to fulfill this role. In fact they were designated as scouting cruiser (sakuteki junyokan) or aircraft cruiser (koku junyokan). Cruiser MOGAMI was modified (after damage received in the Battle of Midway) to aircraft cruiser standards.
9. Northern Force Orders Communications Lessons of the Battle of Attu
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