Australia–Japan Research Project at the Australian War Memorial
The human face of war
South Seas Force units

Strength on 4 October 1941 (time of mobilisation)
55th Infantry Group Headquarters (Maj Gen HORII Tomitarô)
144th Infantry Regiment (see note)
55th Cavalry Regiment 3rd Company (less one platoon) plus 55th Cavalry Regiment Pom-pom Gun Squad (two machine-guns, one pom-pom gun)
55th Mountain Artillery Regiment 1st Battalion (three companies, 12 guns)
55th Engineer Regiment 1st Company (four platoons) plus Materials Platoon (part strength)
55th Division Signals Unit (part strength, two wired squads)
55th Supply Regiment 2nd Company (motorised)
55th Division Medical Unit (one-third strength)
55th Division 1st Field Hospital
55th Division Veterinary Workshop (one-third strength)
55th Division Disease Prevention and Water Supply Unit (part strength)
47th Field Artillery (type B) Battalion (one company)
10th Independent Engineer Regiment 3rd Company (less one platoon)
Shipping Artillery Regiment (part strength)
37th Anchorage Command (part strength)
105th Sea Duty Company (one platoon)
1st Shipping Signals Unit 15th Platoon

Note:
144th Infantry Regiment included: Regimental HQ, three battalions, Infantry Gun Company, Signals Unit, Ammunition Squad.
Battalion comprised: three infantry companies, one machine-gun company (four guns), one battalion gun platoon (two guns).
Infantry gun company comprised: two regimental guns, two pom-pom guns.
Infantry company comprised: three platoons (three light machine-guns, four grenade launchers)
Signals Unit comprised: code machines (Infantry group HQ had three code machines).

Strength on 16 May 1942 (time of issue of orders for FS Operation)
Commander: Major General HORII Tomitarô
55th Infantry Group HQ
144th Infantry Regiment
55th Cavalry Regiment 3rd Company (less one platoon) plus 55th Cavalry Regiment Pom-pom Gun Squad
55th Mountain Artillery Regiment 1st Battalion
55th Engineer Regiment 1st Company plus Materials Platoon (part strength)
55th Division Signals Unit (part strength)
55th Supply and Transport Regiment 2nd Company
55th Division Medical Unit (part strength)
55th Division 1st Field Hospital
55th Division Veterinary Workshop (part strength)
55th Division Disease Prevention and Water Supply Unit (part strength)
47th Field Artillery (type B) Battalion (less one company)


Strength on 18 July 1942
Commander: Major General HORII Tomitarô
55th Infantry Group Headquarters
144th Infantry Regiment
55th Cavalry Regiment 3rd Company (less one platoon) plus 55th Cavalry Regiment Pom-pom Gun Squad
55th Mountain Artillery Regiment 1st Battalion
55th Engineer Regiment 1st Company plus Materials Platoon (part strength)
55th Division Signals Unit (part strength)
55th Supply and Transport Regiment 2nd Company
55th Division Medical Unit (part strength)
55th Division 1st Field Hospital
55th Division Veterinary Workshop (part strength)
55th Division Disease Prevention and Water Supply Unit (part strength)
15th Independent Engineer Regiment (less one company) plus Takasago Giyûtai
Army Signals Unit (part strength)
24th Field Disease Prevention and Water Supply Unit (part strength )
Shipping Transport Units
10th Independent Engineer Regiment (one company plus one platoon)
40th Sea Duty Company (less two platoons)
105th Sea Duty Company (one platoon)
120th Land Duty Company (one platoon)
37th Anchorage Command
Shipping Transport Signals Unit (part strength)