Image of cover.


[Declassified] Confidential
15 January 1945




Japanese Naval Ground Forces

"Know Your Enemy!"







CinCPac-CinCPOA Bulletin 11-45















Japanese Naval Ground Forces

As the war draws closer to the main islands of JAPAN, enemy units are forced into new functions of home defense. Naval ground units, which played an important part in JAPAN's early victories, may assume an equally important role in the final attempt to deny beaches and approaches to troops invading the Empire.

An earlier survey of this subject ("Weekly Intelligence," Vol. I, No. 12) pointed out that in the period immediately following the MARIANAS campaigns the overseas use of Naval ground units by the enemy was decreasing. The offensive power of these troops, blunted in the GILBERTS and MARSHALLS, had been largely ended during the NEW GUINEA and MARIANAS campaigns. Many units had been destroyed. Disbandment and absorption of others apparently indicated that JAPAN intended to confine Naval troops outside the Empire to purely defensive garrison and service functions. The PHILIPPINES campaign may result in the isolation of most of the remaining garrisons.

In the Empire, however, the functions of Naval ground units remain important. The Navy bears the formal responsibility for the defense of harbors, Naval stations and the approaches to the Inland Sea. It seems likely, moreover, that reactivated and increased Naval ground troop units will cooperate with the Army in defensive fighting in almost any threatened locality.

The home reservoir for Naval ground replacements is large. Despite recent heavy ship losses there has apparently been no curtailment in JAPAN's Naval training programs. The number of personnel awaiting assignment in receiving barracks, training schools and other shore stations must therefore be rapidly increasing. It is logical to assume that much of this surplus Naval personnel will be used to organize and enlarge to combat strength such badly-needed organizations as [anti-aircraft] AA Defense Units, Guard Units and Special Naval Landing Forces [SNLF] (now assigned primarily defensive functions). In any case, unattached Naval personnel awaiting assignment are at least given temporary combatant organization and duties as a part of the enemy's defensive preparations. Large numbers of permanent personnel attached to the Empire's many Naval Stations will also presumably be given an emergency defense role.

Considerable new information on Naval ground units has appeared in official captured documents. This and other information is summarized in the three basic charts enclosed herewith, which are believed to present a more accurate view of the organization and disposition of Jap naval ground units than has hitherto been available.

Chart 1 shows the Naval chain of command as it relates to ground units in the Empire. This chart is based on a captured chart (CINCPAC-CINCPOA Item No. 13,069) which will be reproduced in full in a "Know Your Enemy" publication on the Japanese Air Force now under preparation.

(Comment: Following the original captured chart, Chart 1 places Guard Districts, Naval Districts, and Fleets on the same echelon as the Navy Ministry and Naval General Staff. This apparent illogicality is partly explained by the

--1--

original chart, which indicates that a more logical working relation may be achieved through a complex parallel structure of "delegated" and "directive" authority. Since this parallel structure has no further bearing on Naval ground troop organization, it is not reproduced in Chart 1).

Chart 2 shows the chain of command of Naval ground forces outside the Empire. This chart was not taken from any single captured document, but is a logical summary of all available reliable intelligence on the subject.

Chart 3, also drawn from many sources, summarizes existing information on the actual current disposition of major Naval ground units which are now active. Locations of SNLFs, AA Defense Units and Construction Battalions are listed separately under the respective units. The disposition of major units shown on Chart 3 will shed considerable light on the probable current projected employment of Japanese Naval ground troops.

The text following is primarily an explanation of these charts. Important units will be discussed in the order of their appearance on Charts 1 and 2. Unimportant units and units not closely related to the ground troop organization will be omitted in the text.

Units in the Empire

Of the organizations on the highest Japanese Navy echelon, only Fleets, Naval Districts and Guard Districts have ground troops under their immediate command. Supporting ground troops attached to Fleets will be discussed in the section on "Units Outside the Empire."

Naval Districts

JAPAN'S four Naval Districts - YOKOSUKA, KURE, MAIZURU and SASEBO - control many functions of the utmost importance. In addition to the first-class Navy Yards located in each, Districts have charge of all recruiting, replacements, the formation of new ground units, training schools and the defense of their areas. The most important ground units attached to Naval Districts are discussed below in the order of their appearance on Chart 1:

1. Civil Engineering Departments (SHISETSUBU)

Civil Engineering Departments are responsible for the training and replacement of technicians and laborers for all Naval ground units. Construction Battalions, the primary Naval construction units, are under the command of District CE Departments during their training periods, after which they are assigned to Fleets. Construction Departments of Base Forces and Special Base Forces receive their replacements from the CE Departments through the Base Force commands.

2. Naval Barracks (KAIHEIDAN)

Naval barracks provide quarters and training for personnel awaiting assignment. The number of permanent personnel attached to each barracks is shown in

--2--

the following table. This serves as an indication of the relative size of the barracks.

Barracks   Strength
AIURA           1,589
CHINKAI           608
KURE           569
MAIZURU           983
OTAKE           1,589
SASEBO           558
TAKAO           608
TAKEYAMA           1,589
YOKOSUKA           725

3. Guard Units (KEIBITAI)

Guard Units in the Empire are believed to serve primarily as nuclei for the defense of the areas in which they are located. They consist primarily of AA and CD [coastal defense] artillery. However, since special-weapons units, tank units and surface craft are often attached, Guard Units are capable of offensive action. They include the following departments: 1st Lieutenant, Land Defense (this department may be organized as a Special Naval Landing Force), Sea Defense, Medical, and Supply. Assigned strengths of known Guard Units attached to Naval Districts are as follows:

Organization   Strength
KURE Guard Unit           208
MAIZURU Guard Unit           688
SASEBO Guard Unit           718
YOKOSUKA Guard Unit           812

(Note: Guard Units may be expanded in emergency, though they do not have the extreme flexibility of Defense Units).

4. Defense Units (BOBITAI)

Defense Units are located only in the Empire. Units of this type which were formerly stationed overseas have been absorbed or redesignated as Guard Units or Base Forces.

Primary weapons of Defense Units are mines and artillery. They contain no mobile troops. However, in an emergency personnel from Naval barracks and other unattached Naval personnel might serve under Defense Units as mobile troops. Organization of a typical Defense Unit is shown in the following diagram.

--3--

Image of Organizational Chart: Defense Unit (Bobitai). Note: 'Departments may be combined or left out, depending on the size of a given Defense Unit. A Construction Dept. (SETSUEIKA) may be included if circumstances warrant.'
Defense Unit (Bobitai) Organizational Chart

Strengths of known Defense Units attached to Districts are listed below. Since these units are capable of considerable expansion, the following figures are believed to represent nuclei only.

Organization   Strength
ISE Defense Unit           163
MAIZURU Defense Unit           358
ONAGAWA Defense Unit           123
OSHIMA Defense Unit           202
SAEKI Defense Unit           479
SASEBO Defense Unit           506
SHIMONOSEKI Unit           249
YOKOSUKA Defense Unit           440

5. Naval Air Groups

A full discussion of ground personnel attached to Naval Air Groups for service and maintenance will appear in another special "Know Your Enemy" publication now under preparation.

Guard Districts

JAPAN's Guard Districts - located both within and outside the Empire, at OMINATO, OSAKA, CHINKAI, TAKAO, HAINAN - are similar to Naval Districts. They exist on the same echelon, and they include territory of similar extent. They do

--4--

not, however, include Navy Yards, barracks or training schools.

1. Civil Engineer Departments (SHISETSUBU)

Civil Engineer Departments of Guard Districts are on the same echelon as CE Departments of Naval Districts. It is believed that their training functions are similar. They do not, however, appear to have the replacement responsibilities of Naval District CE Departments in the assignment of workers to overseas construction units.

2. Guard Units and Defense Units

Guard Units and Defense Units under Guard Districts are similar in function and organization to those under Naval Districts. The assigned strengths of known Guard and Defense Units under Guard District command are as follows:

Organization   Strength
CHINKAI Guard Unit           208
TAKAO Guard Unit           294
OMINATO Guard Unit           ?
CHINKAI Defense Unit           315
KII Defense Unit           249
OMINATO Defense Unit           290
PORT ARTHUR Defense Unit           136
SOYA Defense Unit           ?

3. Unattached Personnel

It is believed that unattached personnel within both Naval and Guard Districts are organized on an emergency basis as District SNLFs or Land Combat Units. A sample T/O of such an organization follows:

Image of Organizational Chart: Unattached Personnel.

--5--

Units Outside the Empire

Ground Units outside the Empire are attached to the Fleets in whose areas they operate. Areas under the command of the various Fleets are indicated in Chart 3. Fleet ground organizations are clearly separated into administrative and tactical units.

Administrative Units

Shore-based administrative organizations carry out many of the duties of Fleet administration. They are also assigned important maintenance and service responsibilities and, as necessary, limited tactical responsibilities in their areas.

1. Base Forces (KONKYOCHITAI)

Base Forces are subordinate to Fleets and are assigned to sub-areas for the administration of ground and surface units. Since these functions parallel those of Fleet commands, Base Forces are usually located in places where no Fleet Headquarters exist.

In addition to their administrative functions, Base Forces necessarily undertake limited tactical responsibilities. This is demonstrated by the Japanese Administrative Order establishing Base Forces, which states that these Forces are responsible for defense and communications in their areas and for the security of adjacent waters. In forward areas, these defense functions are obviously considerable. The same Order also states that Base Forces are responsible "when required" for "supply, construction and repair, and medical aid in behalf of the Fleet."

The organization of units composing Base Forces (see Chart 2) is obviously determined by these triple administrative, service and tactical responsibilities and is therefore subject to considerable variation. A list of strengths of known Base Forces is combined for greater convenience in use with the list of Special Base Forces which appears on page 8-9. Note that the assigned strengths of Base Forces vary considerably with their locations. Forces in forward areas, where tactical responsibilities are obviously considerable, are large. Forces in rear areas have few tactical responsibilities and are ordinarily rarely called on for Fleet maintenance functions; consequently, they are small in size. When a rear area becomes active and Fleet activities increase, units are added to the area's Base Force.

2. Fleet Service Units

Fuel Depots, Construction and Repair Departments and all other administrative and service units except Base Forces shown on Chart 2 are integral Fleet service units. These integral Fleet units perform functions identical to those performed by subordinate units of Base Forces. They are, however, separate and distinct from these units within Base Forces. Fleet service units are located at Fleet Headquarters, where no Base Forces ordinarily exist.

--6--

An example of the relation between Base Forces and Integral Fleet units is provided by the development of the 4th Base Force (TRUK) and the 8th Base Force (RABAUL). These two Base Forces, unlike all others, were located at Fleet Headquarters. Maintenance functions which would normally have been theirs were performed largely by Fleet service units. Tactical responsibilities in these areas were also undertaken by Fleets. The two Base Forces were therefore originally small units, almost entirely administrative.

With the deterioration of the 8th Fleet and the departure of the CenPac Fleet from the TRUK Area, the two Base Forces were forced to assume larger tactical responsibilities. They also had to take over the maintenance duties formerly performed by Fleet service organizations. The former Fleet service units isolated in TRUK and RABAUL by the departure of the Fleets are, in fact, believed to have been incorporated into the Base Force organizations. In this way, both Forces probably became capable of performing all the normal functions of Base Forces.

Tactical Units

1. Special Base Forces (TOKUBETSU KONKYOCHITAI)

Special Base Forces are assigned to Guard Districts and Fleets for employment. It is not known which Special Base Forces are assigned to Guard Districts.

Special Base Forces have considerable similarity to Base Forces in function. They are, however, primarily tactical rather than administrative organizations.

This difference is demonstrated by the locations and assigned strengths of Special Base Forces, indicated on the list which follows. Special Base Forces are ordinarily located either at Fleet Headquarters or in forward areas. The Special Base Forces located in rear areas are obviously mere nuclei, capable of expansion in emergency. Those located in forward areas bear considerable combatant responsibility and often have Guard Units, SNLFs and other combatant units under their command. Special Base Forces located at Fleet Commands share their service, maintenance and administrative functions with integral Fleet units. Special Base Forces are therefore assigned "partial responsibility" for their various defense and maintenance functions by the order establishing them, whereas Base Forces are assigned full responsibility for similar functions.

The difference between Base Forces and Special Base Forces is further demonstrated by the fact that the 5th Special Base Force (SAIPAN) and the 30th Special Base Force (PALAU) were changed to Base Forces when Admiral NAGUMO's CenPac Area Fleet Headquarters was moved to SAIPAN. Since this Fleet Headquarters was temporary, it did not have the integral service and administrative units which ordinarily make a Base Force unnecessary at Fleet Headquarters. The new Base Forces were enlarged to provide for the Fleet's administrative and service needs. According to a POW captured on SAIPAN, an additional reason for the change was that Admiral NAGUMO, again departing from usual practice, wanted no separate tactical commands in his new Fleet Area. This objective also was achieved by changing the two units from Special Base Forces (tactical) to Base Forces (largely administrative).

--7--

Special Base Forces, probably because of their tactical responsibilities in forward areas, have more definite T/Os than Base Forces and are not subject to such drastic changes in size. The typical organization of a Special Base Force is indicated on Chart 2.

Base Forces and Special Base Forces identified since the beginning of hostilities are listed below with their organizational strength. (Comment: An asterisk after a strength indicates that it was obtained from unofficial documents).

Organization Location Strength
AMOY Area Spec Base Force AMOY 851  
BAKO Area Spec Base Force BAKO 336  
CANTON Area Base Force (disbanded)    
CHICHI JIMA Area Spec Base Force CHICHI JIMA 225  
CHISHIMA Area Spec Base Force CHISHIMA    
HAINAN Is. Base Force (disbanded)    
HANKOW Area Spec Base Force HANKOW (disbanded)    
HONG KONG Area Spec Base Force HONGKONG 1,350  
OKINAWA Area Base Force OKINAWA    
PORT ARTHUR Area Spec Base Force PORT ARTHUR 247  
RASHIN Area Spec Base Force RASHIN 253  
SHANGHAI Spec Base Force SHANGHAI    
TSINGTAO Area Spec Base Force TSINGTAO 851  
YANGTZE RIVER Area Spec Base Force HANKOW 540  
1st Base Force BUIN    
2d Spec Base Force WEWAK (disbanded)    
3d Spec Base Force PALAU - TARAWA (disbanded)    
4th Base Force TRUK 520*
5th Base Force SAIPAN 1,049*
    1,437  
6th Base Force JALUIT - KWAJALEIN    
7th Base Force WEWAK    
8th Base Force RABAUL    
9th Spec Base Force SABANG - PENANG 722  
10th Spec Base Force SINGAPORE 620  
11th Spec Base Force SAIGON 519  
12th Spec Base Force ANDAMAN 1,166  
13th Base Force RANGOON    
14th Base Force KAVIENG    
15th Base Force Unlocated    
20th Base Force Unlocated (March, 1944)    
21st Spec Base Force SURABAYA 1,287  
22d Spec Base Force BALIKPAPAN 1,166  
23d Spec Base Force MAKASSAR 1,048  
24th Base Force ENDE, FLORES Is.    
25th Spec Base Force KOKAS    
26th Spec Base Force KAU BAY, HALMAHERA 265  
27th Spec Base Force WEWAK    
28th Base Force BIAK - SARMI    

--8--

Organization Location Strength
30th Base Force PALAU    
31st Spec Base Force N. PHILIPPINES    
32d Spec Base Force DAVAO 722  
33d Spec Base Force CENTRAL PHILIPPINES    
51st Base Force KURILES (disbanded)    
52d Base Force Unlocated (disbanded)    

2. Guard Units (KEIBITAI)

Composition and function of Guard Units have already been described under Empire-based units. Guard Units outside the Empire are ordinarily assigned by Fleets to Base Forces and Special Base Forces. They are in turn assigned by these commands to take charge of the land and sea defense of particular localities.

Guard Units, within their localities, take full charge of the distribution of troops and weapons, maintenance of lookout and communications, and patrol of nearby waters. Air units within the territory of Guard Units are independent of the Guard Unit command, but the Guard Unit is responsible for the defense of airfields.

Guard Units are frequently assigned semi-civil responsibilities such as the internment of foreigners, the policing of natives, etc. within their jurisdictions.

Locations and assigned strengths of known Guard Units outside the Empire are listed below. Note that these units, like most Naval ground units, are subject to considerable variation in size according to the current importance of activity in their areas and the presence or absence of other military units. (Comment: Strengths marked with an asterisk were obtained from unofficial captured documents).

Organization Location Strength
CANTON Guard Unit CANTON 208  
CHUSAN Guard Unit CHUSAN Is. 455  
IWO JIMA Guard Unit IWO JIMA    
KIUKIANG Guard Unit KIUKIANG 556  
MARCUS Guard Unit MARCUS 765  
NANKING Guard Unit NANKING 497  
1st Guard Unit SURABAYA 347  
2d Guard Unit TARAKAN 665  
3d Guard Unit MAKASSAR 546  
4th Guard Unit KOEPANG 1,036  
5th Guard Unit NW NEW GUINEA 711  
6th Guard Unit WAINGAPOE 941  
7th Guard Unit NW NEW GUINEA 1,070  
9th Guard Unit PENANG 302  
12th Guard Unit RANGOON 353  
13th Guard Unit Under 1st So. Exp. Flt. 486  
14th Guard Unit NICOBARS 772  

--9--

Organization Location Strength
15th Guard Unit HAINAN 1,249  
16th Guard Unit HAINAN 769  
17th Guard Unit (BURMA) Under 1st So. Exp. Flt. 195  
18th Guard Unit MANOKWARI 697  
19th Guard Unit BIAK    
20th Guard Unit AMBON    
21st Guard Unit KAIMANA 524  
25th Guard Unit NICOBAR Is. 319  
31st Guard Unit MANILA 724  
32d Guard Unit DAVAO    
33d Guard Unit JOLO    
35th Guard Unit S. PHILIPPINES    
36th Guard Unit NEGROS    
41st Guard Unit TRUK 2,259*
    173  
42d Guard Unit PONAPE 150  
43d Guard Unit PALAU    
44th Guard Unit WOLEAI 200*
45th Guard Unit PALAU    
46th Guard Unit YAP 500*
51st Guard Unit SHIKOTAN 2,240  
52d Guard Unit MUSASHI WAN    
53d Guard Unit TENNEI    
54th Guard Unit GUAM 759*
    269  
55th Guard Unit SAIPAN 2,504*
56th Guard Unit TINIAN - ROTA    
61st Guard Unit KWAJALEIN 557  
62d Guard Unit JALUIT 1,940*
    557  
63d Guard Unit TAROA 949*
    557  
64th Guard Unit WOTJE 1,168*
    557  
65th Guard Unit WAKE 1,425*
    1,202  
66th Guard Unit MILLE 1,414  
67th Guard Unit NAURU 1,135  
68th Guard Unit TRUK 503  
69th Guard Unit KUSAIE    
81st Guard Unit RABAUL 602  
82d Guard Unit LAE - SOLOMONS 480  
83rd Guard Unit KAVIENG 429  
84th Guard Unit MADANG 480  
85th Guard Unit PALAU 756  
86th Guard Unit RABAUL 709  
87th Guard Unit BUKA 734  
88th Guard Unit MANUS Is. 522  
89th Guard Unit NAMATANAI 613  
90th Guard Unit HOLLANDIA    
91st Guard Unit SARMI    

--10--

3. Special Naval Landing Forces (TOKUBETSU RIKUSENTAI)

SNLFs, like some other Naval ground units, have varied greatly with the course of the war. In the early months of the war, their mission was primarily one of assault. It has since become almost entirely defensive. Consequently, SNLFs, formerly consisting principally of infantry, have become chiefly heavy-weapons units.

Many SNLFs have been destroyed or so shattered that the remnants have been absorbed by units of other types. In several instances two or more SNLFs have been combined for particularly important missions.

A sample T/O of a well-balanced combined SNLF, equipped for primarily defensive duties, appears on the opposite [following] page. (This chart was originally published by CICSOPAC in March, 1944). Although this particular unit (the 8th Combined SNLF) no longer exists, the organization outlined is believed representative of the fairly recent development of SNLFs.

SNLFs identified since the beginning of hostilities are listed below. (Comment: "WD" indicates that data was derived from confidential Order of Battle publications issued by the War Department).

Organization Location Strength
YOKOSUKA #1 SAIPAN 1,326  
YOKOSUKA #2 NAURU 1,167  
YOKOSUKA #3 RABAUL (WD) 844  
YOKOSUKA #4 HAINAN    
YOKOSUKA #5 NEW GUINEA-NEW BRITAIN 1,009  
YOKOSUKA #6 GILBERTS 1,513  
YOKOSUKA #7 Became 89th Guard Unit 1,380  
YOKOSUKA #8 Unlocated    
SASEBO #1 PHILIPPINES (WD) 1,612  
SASEBO #2 MANDATES 1,441  
SASEBO #3 Unlocated 1,170  
SASEBO #5 NEW GUINEA 1,345  
SASEBO #6 SOLOMON 1,513  
SASEBO #7 TARAWA 1,660  
SASEBO #8 HAINAN    
SASEBO #101 TRUK 218  
SASEBO #102 TATEYAMA    
KURE #1 TIMOR (WD) 1,404  
KURE #2 Unlocated 1,394  
KURE #3 SOLOMONS-NEW GUINEA 1,170  
KURE #4 MANDATES (WD)    
KURE #5 NEW GUINEA ? 1,009  
KURE #6 Became 88th Guard Unit 1,539  
KURE #7 BUIN 1,660  

--11--

Organizational Chart: 8th Combined SNLF.
8TH Combined SNLF (Org. Chart)

--12--

Organization Location Strength
KURE #8 Became 14th Guard Unit 668  
KURE #101 TATEYAMA    
MAIZURU #1 HAINAN 1,316  
MAIZURU #2 NEW GUINEA 1,071  
MAIZURU #3 Inactivated ? 460  
MAIZURU #4 SOLOMONS 963  
MAIZURU #6 Unlocated    
SHANGHAI SHANGHAI 1,979  
2d Combined Unlocated 637  
7th Combined BUIN Composed of KURE #7    
8th Combined Became 14th Base Force 1,465  

4. AA Defense Units (BOKUTAI)

Naval AA Defense Units are independent units assigned by Fleets to Base Forces, Special Base Forces, Guard Units and SNLFs, according to tactical needs. As indicated in the charts on pages 16 and 17, AA Units are of three types. Type A includes AA artillery and machine-guns, Type B machine-guns only, and Type C machine-guns and machine-cannon.

Locations of AA Defense Units identified since the beginning of hostilities are listed below.

Organization           Location
1st AA Defense Unit           SOLOMONS
2nd AA Defense Unit           BISMARCKS
3d AA Defense Unit           NEW GUINEA
4th AA Defense Unit           BUIN
5th AA Defense Unit           BISMARCKS
6th AA Defense Unit           TRUK
7th AA Defense Unit           BUIN
8th AA Defense Unit           Under 1st Southern Expeditionary Fleet
9th AA Defense Unit           KURILES ?
10th AA Defense Unit           KURILES
11th AA Defense Unit           BISMARCKS
12th AA Defense Unit           BISMARCKS
13th AA Defense Unit           BUIN
14th AA Defense Unit           BISMARCKS
15th AA Defense Unit           NEW GUINEA
16th AA Defense Unit           SOLOMONS
17th AA Defense Unit           SOLOMONS
18th AA Defense Unit           SOLOMONS
19th AA Defense Unit           BISMARCKS
20th AA Defense Unit           SOLOMONS
21st AA Defense Unit           BISMARCKS
22nd AA Defense Unit           BISMARCKS

--13--

Organization           Location
23d AA Defense Unit           BISMARCKS
24th AA Defense Unit           SOLOMONS
25th AA Defense Unit           KAI Is.
26th AA Defense Unit           KURILES
27th AA Defense Unit           KURILES
28th AA Defense Unit           SOLOMONS
29th AA Defense Unit           Under 2d Southern Expeditionary Fleet
30th AA Defense Unit           AMBON
31st AA Defense Unit           WEWAK
32nd AA Defense Unit           SOEMBA Is.
33d AA Defense Unit           BIAK Is.
34th AA Defense Unit           MERGUI
35th AA Defense Unit           KAI Is.
36th AA Defense Unit           BISMARCKS
41st AA Defense Unit           Under 1st Southern Expeditionary Fleet
42d AA Defense Unit           TRUK
43d AA Defense Unit           TRUK
44th AA Defense Unit           BISMARCKS
45th AA Defense Unit           BISMARCKS
46th AA Defense Unit           TRUK
47th AA Defense Unit           MARIANAS
48th AA Defense Unit           CAROLINES
49th AA Defense Unit           WOLEAI
50th AA Defense Unit           WAINGAPOE
51st AA Defense Unit           NICOBAR Is.
52nd AA Defense Unit           KAVIENG
53d AA Defense Unit           Under 2d Southern Expeditionary Fleet
54th AA Defense Unit           KAI Is.
55th AA Defense Unit           PORT BLAIR
56th AA Defense Unit           KOKAS
57th AA Defense Unit           NEW GUINEA
58th AA Defense Unit           ANDAMAN Is.
59th AA Defense Unit           WOLEAI
60th AA Defense Unit           GUAM
61st AA Defense Unit           Under 4th Fleet
62d AA Defense Unit           Under 2d Southern Expeditionary Fleet
63d AA Defense Unit           BISMARCKS
64th AA Defense Unit           BISMARCKS
65th AA Defense Unit           BISMARCKS
66th AA Defense Unit           Under 2d Southern Expeditionary Fleet
67th AA Defense Unit           BISMARCKS
68th AA Defense Unit           KUSAIE
69th AA Defense Unit           BISMARCKS
70th AA Defense Unit           KOTARADJA
81st AA Defense Unit           TRUK
82d AA Defense Unit           MARIANAS
83d AA Defense Unit           MARIANAS
84th AA Defense Unit           MARIANAS/TRUK

--14--

Organization           Location
85th AA Defense Unit           TRUK
86th AA Defense Unit           TRUK
87th AA Defense Unit           Under 4th Southern Expeditionary Fleet
88th AA Defense Unit           NANCOWRY
89th AA Defense Unit           TATEYAMA
90th AA Defense Unit           PALAU
91st AA Defense Unit           PALAU
92d AA Defense Unit           TATEYAMA
93d AA Defense Unit           TATEYAMA
94th AA Defense Unit           TATEYAMA
95th AA Defense Unit           PHILIPPINES
96th AA Defense Unit           Under 2d Southern Expeditionary Fleet
97th AA Defense Unit           TAWI TAWI
101st AA Defense Unit           KENDARI
102d AA Defense Unit           SABANG
103th AA Defense Unit           SURABAYA
104th AA Defense Unit           MERGUI
105th AA Defense Unit           Under 4th Southern Expeditionary Fleet
106th AA Defense Unit           BABO
107th AA Defense Unit           AMBON
108th AA Defense Unit           SURABAYA
109th AA Defense Unit           SURABAYA
110th AA Defense Unit           AMBON
111th AA Defense Unit           TATEYAMA
112th AA Defense Unit           Under 1st Southern Expeditionary Fleet
113th AA Defense Unit           SURABAYA
114th AA Defense Unit           DAVAO
115th AA Defense Unit           KAIMANA
121st AA Defense Unit           TATEYAMA
122d AA Defense Unit           PALAU
123d AA Defense Unit           TATEYAMA

5. Shipboard AA Defense Units (SEMPAKU BOKUTAI)

Shipboard AA Defense Units differ in organization from all three types of shore-based Defense Units. Normally, shipboard units do not exceed 124 men. Such organizations are believed to be assigned to convoys as needed and divided among the several ships.

Distribution of known Shipboard AA Defense Units is indicated by the following list.

Organization           Location
501st           CAROLINES
502d           TRUK
503d           Under 1st Southern Expeditionary Fleet
511th           TRUK

--15--

(AA) Air Defense Unit (BOKUTAI)
Types "A" and "C"

(AA) Air Defense Unit (BOKUTAI) Types 'A' and 'C' (Organizational Chart).

--16--

(AA) Air Defense Unit (BOKUTAI)
Type "B"

(AA) Air Defense Unit (BOKUTAI) Types 'B' (Organizational Chart).

--17--

Organization           Location
521st           CAROLINES
522d           TRUK
531st           CAROLINES

6. Construction Battalions (SETSUEITAI)

Construction Battalions are highly mobile independent units, fully equipped for major construction tasks. Following their training period under the Civil Engineering Departments of Naval Districts, they are assigned to Fleets. Fleets assign them in turn to Base Forces, Special Base Forces and Guard Units for work on particular projects, such as airfields and field fortifications.

Construction Battalions are made up of skilled workers, supervised by civil engineers and Naval officers. They are internally organized according to the laborers' special skills. A sample organization is demonstrated by the diagram reproduced on page 20.

Construction Battalions maintain a close liaison with other Naval construction units. When Battalions are located at Fleet Headquarters, they receive supplies and supervision from Fleet Civil Engineering Departments, which are one type of the integral Fleet service units discussed above. When Battalions are located in Base Force Sub-Areas, these functions of supervision and supply are performed by Base Force Construction Departments (KENSETSUBU), which are subordinate units of Base Forces.

Locations of Construction Battalions identified since the beginning of the war are listed below. (Comment: "WD" indicates that data was derived from confidential Order of Battle publications issued by the War Department).

Organization           Location
1st Const. Bn.           BALIKPAPAN (WD)
2d Const. Bn.           RABAUL (WD)
7th Const. Bn.           TRUK (WD)
10th Const. Bn.           RABAUL
11th Const. Bn.           GUADALCANAL
12th Const. Bn.           KAVIENG
13th Const. Bn.           GUADALCANAL
14th Const. Bn.           BISMARCKS
15th Const. Bn.           NEW GUINEA
16th Const. Bn.           BISMARCKS
17th Const. Bn.           BISMARCKS
18th Const. Bn.           NEW IRELAND
19th Const. Bn.           BUKA (WD)
20th Const. Bn.           BUKA
21st Const. Bn.           BUKA
22d Const. Bn.           Ex-SOLOMONS
23d Const. Bn.           SINGAPORE (WD)
24th Const. Bn.           AMBON

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Organization           Location
26th Const. Bn.           SOLOMONS
28th Const. Bn.           BISMARCKS
30th Const. Bn.           PARAMUSHIRO (WD)
32d Const. Bn.           SOLOMONS
34th Const. Bn.           BISMARCKS
36th Const. Bn.           KAI ISLANDS
40th Const. Bn.           KOTARADJA
43rd Const. Bn.           PALAU/YAP (WD)
101st Const. Bn.           BISMARCKS
103d Const. Bn.           KAU (WD)
111th Const. Bn.           NAURU/JALUIT (WD)
121st Const. Bn.           SOLOMONS
131st Const. Bn.           SOLOMONS
181st Const. Bn.           RABAUL (WD)
201st Const. Bn.           SAGAN, NEW GUINEA
202d Const. Bn.           BIAK (WD)
203d Const. Bn.           KAU, HALMAHERA
204th Const. Bn.           HAHA JIMA
205th Const. Bn.           PALAU
206th Const. Bn.           YAP
207th Const. Bn.           SAIPAN
211th Const. Bn.           SOLOMONS
212th Const. Bn.           BISMARCKS
213th Const. Bn.           WAINGAPORE
214th Const. Bn.           PALAU
215th Const. Bn.           DAVAO
216th Const. Bn.           WOLEAI
217th Const. Bn.           GUAM
218th Const. Bn.           GUAM
221st Const. Bn.           TRUK/PONAPE
222nd Const. Bn.           CAROLINES
223d Const. Bn.           SAIPAN/ROTA
224th Const. Bn.           KAU, HALMAHERA
225th Const. Bn.           DAVAO
226th Const. Bn.           TINIAN
227th Const. Bn.           TRUK
231st Const. Bn.           MALAYA (WD)
232d Const. Bn.           KAIMANA
233d Const. Bn.           TINIAN
234th Const. Bn.           NICOBAR ISLANDS
235th Const. Bn.           BACOLOD, PHILIPPINES
241st Const. Bn.           SAGAN D. NEW GUINEA
301st Const. Bn.           DAVAO
311th Const. Bn.           CENTRAL PHILIPPINES under 33d SBF.

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111th Construction Battalion (Pioneers)

111th CONSTRUCTION BATTALION (PIONEERS) (Organizational Chart).

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