Home Page World War II Armed Forces — Orders of Battle and Organizations Last Updated 15.10.2014
Imperial Japanese Army
Authorized Organization
Regular Infantry Division (Square)
8th December 1941
Regular Infantry Division (square)
Symbols Glossary
This depicts a typical organization. As can also be seen from the diagram above, actual organizations and equipment could vary from division by division. The square (four infantry regiment) infantry division was being gradually phased out by late 1941. On paper, this type of division had about 25,000 men. But the divisions were seldom as neat and tidy as the diagram above. Elements were consistently being attached or detached, so that some divisions had as few as 17,000 men and some as others as many as 32,000.

The units in the divisions did not not always have the same size or configuration. A typical example would be the reconnaissance "regiment". In some divisions this was a cavalry-motorized battalion, in others it was a battalion-sized unit of horse cavalry, and in some divisions a reconnaissance element was missing altogether.

The artillery also suffered variations — in one case (19th Infantry Division) even having two regiments — some being equipped with different types and numbers of guns.

The size of the Transport Regiment also tended to vary, depending on the mission assigned to the division, and whether the regiment itself was horse-drawn, partially or wholly motorized. For example, the transport regiment of the 18th Motor Division had one horse-drawn company and three truck companies.

In the process of converting these divisions to the triangular (three infantry regiment) organization, one brigade headquarters and an infantry regiment might be withdrawn from the division and operate indepndently, with the appropriate support units attached. In case the separation was permanent, the remaining brigade headquarters would be reconfigured and redesignated as the infantry group headquarters.

Infantry Divisions (Square)
(Type) Division
        Commanding General
 Raised Infantry Artillery Recon
Transport Other
(Type) Brig Inf Rgts Brig Inf Rgts (Type) Grp Art Rgt Equipment (Type) Rgt
(A)    3
        LTG Fusataro TOYOSHIMA
14.05.1881 (A1) 5 6  
29 {18}
(A1)    3 Fld 36   75mm 3 Cav 3 (A1) 3 3  
(A)    5 (motorized)
        LTG Masao WATANABE
14.05.1881 (A1) 9 11  
21 21  
(A1)    5 Fld 24   75mm
12 105mm
5 Recon 5 (A1) 5 5 [1][3]
(S)   13
        LTG Eitaro UCHIYAMA
10.09.1941 (S) 26 {58}
103 65 
(S) 19 Mtn 36   75mm 13 Cav 13 (S) 13 13  
(S)   18 (motorized)
        LTG Renya MATAGUCHI
10.09.1941 (S) 23 55
35 114  
(S) 18 Mtn 36   75mm 22 Recon 12 (S) 18 18 [2][3]
(A)   19
        LTG Yoshio KOZUKI
24.12.1915 (A1) 37 73  
38 75  
(A1) 19 15 Fld
25 Mtn
  8 150mm
36   75mm
19 Recon 19 (A1) 19 19  
(A)   20
       LTG Hisashige NAGATSU
24.12.1915 (A1) 39 {77}
40 79 
(A1) 20 26 Fld 36   75mm 20 Recon 20 (A1) 20 20  
(S) 110
        LTG Mamoru IINUMA
16.06.1938 (S) 108 139  
133 110  
(S) 110 Fld 36   75mm 110 Cav 110 (S) 110 110  
(S) 116
        LTG Toshijiro KEUCHI
15.05.1942 (S) 119 109  
130 133  
(S) 122 Fld 36   75mm 120 Cav 116 (S) 116 116  
Type (A) are regular, peacetime (activated) units.
Type (S) are wartime (activated) units.
Infantry regiments in {curly brackets} are those lost during triangularization.
[1] But: 2nd Hygiene and Water Supply Department. Included the Tank Unit, 5th Division.
[2] The 35th Infantry Brigade with 124th Infantry Regiment operated independently as Kawaguchi Detachment, and was still at Camranh Bay.

[3] A standard, (non-motorized), divison had approximately 200 trucks. Only the 5th (860 trucks) and 18th divisions were motorized square divisions. The scarce trucks were for moving the heavy equipment and the artillery, and soldiers not allocated places in motor vehicles were issued bicycles.
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Infantry Regiment Infantry Regiment Field Artillery Regiment Field Artillery Regiment Mountain Artillery Regiment Mountain Artillery Regiment Cavalry Reconnaissance Regiment Cavalry-Mechanized Reconnaissance Regiment Engineer Regiment (Combat) Transport Regiment (Type A1) Transport Regiment (Type A2) Anti-Gas Unit Signal Unit Ordnance Maintenance Unit Medical Unit Veterinarian Hospital Infantry Regiment Infantry Regiment