Japanese Southern Expeditionary Army

The Southern Expeditionary Army was responsible for executing the major land operations of the Centrifugal Offensive by which Japan hoped to seize southeast Asia before the Allies could react. This offensive was completely successful, achieving all of its objectives ahead of schedule and at smaller loss than anticipated.

The location of 21 Division, the area army reserve, is uncertain. Morton places it still in North China until 20 January 1942.

Order of battle, 7 December 1941:

Southern Expeditionary Army (Terauchi; at Saigon)
	1 Parachute Brigade "Dash Forward" (at Nyutabaru, Kyushu)				Deployed to Southeast Asia in December 1942 following the outbreak of war.
		1 Parchute Regiment (at Chiai)
		2 Parachute Regiment (at Saigon)			Conducted airborne attack on Palembang
	21 Division (Tanaka; at Cam Ranh?)				From Kanazawa. Had seen two years' service in China.
	38 Division (Sano; near Hong Kong)				From Nagoya. 20,000 men with motorized transport. Assigned to Southern Expeditionary Army from 23 Army for the attack on Hong Kong. The commander of 23 Army, Sakai, seems to have personally supervised the Hong Kong operation.
		228 Regiment
		229 Regiment
		230 Regiment
	21 Independent Mixed Brigade (Yamagata)				Eventually committed to New Guinea.
	21 Air Regiment (at Gia Lam)
		82 Light Squadron (at Tien Flo)
			12 Ki-48 Lily
		84 Squadron (at Nha Trang)
			9 Ki-27 Nate
	83 Air Regiment (at Sanya)
		71 Squadron
			10 Ki-51 Sonia
		73 Squadron
			9 Ki-51 Sonia
		89 Squadron (at Dau Mot)
			12 Ki-32 Mary
	7 Air Regiment (at Chiai)				Transport for Dash Forward?
		1 Squadron
			6 Ki-59 Theresa
		2 Squadron
			6 Ki-59 Theresa
		13 Squadron
			12 Ki-57 Topsy (at Chiai)
			6 Ki-59 Theresa (at Dau Mot)
	47 Squadron (at Tien Flo)
		9 Ki-44 Tojo			Experimental squadron

	14 Army (Homma)				Responsible for taking the Philippines.
		16 Division (Morioka; at Naze)			From Kyoto. This division had been recently triangularized and had not seen recent combat. Homma did not rate it very highly. Those elements not detached to Magong or Palau were embarked with the Lamon Bay Force.
			9 Regiment
			20 Regiment		At Magong
			33 Regiment		Two of its battalions were at Palau (Kimura Detachment)
		48 Division (Tsuchihashi; at Magong)			Embarked with Lingayen Gulf Force. Formed in 1940 in Formosa and lacked battle experience, but Homma still considered it the best division in 14 Army. It was partially motorized and reinforced with artillery.
		65 Brigade (Nara; at Magong)			From Hiroshima. 6500 mostly older reservists. Considered totally unprepared for combat by its own commander. Intended for garrison duty.
		4 Tank Regiment (at Magong)			Light tanks. Attached to 20 Regiment, 16 Division.
		7 Tank Regiment (at Magong)			80-100 tanks, including "heavy" 13-ton tanks. Attached to 48 Division.
		3 Engineer Regiment (at Takao)
		21 Engineer Regiment (at Magong)

	15 Army (IIda; at Phnom Penh?)				Responsible for taking Burma. Little more than a cadre ln 7 December 1941, with some of its units still in China.
		33 Division (Sakurai; in Central China)			From Sendai. Had seen service in central China.
		55 Division (Takeuchi; on Thai border)			From Zentsuji. Less 143 Regiment, which was assigned to 25 Army.

	16 Army (Imamura; at Tokyo)				Responsible for taking the Netherlands East Indies. Would not deploy to the combat zone until the Philippines and Singapore were isolated.
		2 Division (Maruyama; at Cam Ranh)
		56 Brigade (Sakaguchi; at Palau)			Designated to become the infantry group of 56 Division. Responsible for seizing Tarakan and Balikpapan

	25 Army (Yamashita; at Sanya)				Responsible for taking Malaya
		5 Division (Matsui)			From Hiroshima. One of the finest and most heavily mechanized divisions in the Japanese Army. Also one of the largest, since it was still a square division. Three of its four regiments were assigned to land at Singora and drive down the west coast of Malaya. The fourth (42 Regiment) was assigned to secure Patani.
			41 Regiment
			42 Regiment
			43 Regiment?
			44 Regiment?
			5 Tank Regiment		Attached to 5 Division.
		18 Division (Mutaguchi)			From Kurume. Had considerable combat experience in China. A square division.
			55 Brigade Group (Kawaguchi Detachment; at Kossol?)		Detached to seize points in west Borneo: Miri, Kuching, Brunei
				124 Regiment (at Cam Ranh)
			56 Regiment		Responsible for seizing Kota Baharu.
		56 Division (Watanabe; at Fukuoka)			From Kurume. This division was newly raised and the brigade designated to become its infantry group (56 Brigade) was operating with 16 Army. Yamashita left the headquarters in Japan, where it was effectively part of the area army reserve.
		Imperial Guards Division (Nishimura; on Thai border)			Responsible for securing Thailand and the Kra Peninsula before joining the rest of 25 Army in Malaya
		3 Tank Brigade			Amounted to a full armored division, with four regiments. Three regiments were equipped with 37 M-97 and 20 M-95 tanks; the 14 Regiment was equipped with 45 M-95 tanks.
		143 Regiment			Detailed from 55 Division, 15 Army, to seize points along the Kra Isthmus. Regiment headquarters embarked on a transport off Prachuap; two battalions in two transports and one cargo ship off Jumbhorn; another battalion and three transports off Nakhorn.

	3 Air Division (Sugawara; at Kompong Trach)				There is excellent agreement on the composition of 3 Air Division among various sources.
		3 Air Brigade (Endo)
			27 Light Air Regiment (at Kompong Chanang)
				23 Ki-51 Sonia
			59 Air Regiment
				24 Ki-27 Nate
			75 Light Air Regiment
				25 Ki-48 Lily
			90 Light Air Regiment
				25 Ki-48 Lily
		7 Air Brigade (Yamamoto; at Phnom Penh)
			12 Heavy Air Regiment
				21 Ki-21 Sally
			60 Heavy Air Regiment
				39 Ki-21 Sally
			51 Recon Squadron
				3 Ki-15 Babs 3 Ki-46 Dinah
			64 Air Regiment (at Phiquoc)
				6 Ki-27 Nate 35 Ki-43 Oscar
			98 Heavy Air Regiment (at Saigon)
				42 Ki-21 Sally
		10 Air Brigade (Hirotaka; at Krakor)
			31 Light Air Regiment (at Siem Reap)
				24 Ki-30 Ann
			77 Air Regiment (at Siem Reap)
				36 Ki-27 Nate
			62 Heavy Air Regiment
				22 Ki-21 Sally
			70 Recon Squadron
				8 Ki-15 Babs
		12 Air Brigade (Aoki; at Phiquoc)
			1 Air Regiment
				42 Ki-27 Nate
			11 Air Regiment
				39 Ki-27 Nate
		50 Recon Squadron (at Kompong Trach)
			3 Ki-15 Babs
			2 Ki-46 Dinah
		81 Recon Squadron (at Phnom Penh)
			9 Ki-15 Babs
			7 Ki-46 Dinah

	5 Air Division (Obata, at Heito)				There is significant disagreement among various sources on the composition of 5 Air Division. We use the composition given by Francillon (1979).
		4 Air Brigade (Kawahara; at Chiai)
			8 Light Air Regiment
				27 Ki-48 Lily
				9 Ki-15 Babs
				2 Ki-46 Dinah
			14 Heavy Air Regiment
				18 Ki-21 Sally
			16 Light Air Regiment
				27 Ki-30 Ann
			50 Air Regiment (Hengchun)
				36 Ki-27 Nate
		10 Independent Air Squadron (at Heito)
			52 Recon Squadron
				13 Ki-51 Sonia
			74 Recon Squadron
				10 Ki-36 Ida
			76 Recon Squadron
				9 Ki-15 Babs
				2 Ki-46 Dinah
		11 Air Transport Squadron (at Taichu)
			9 Ki-57 Topsy
		12 Air Transport Squadron (at Phnom Penh)			Not given in Francillon, but identified by Rottman as part of the parachute transport force.
			9 Ki-57 Topsy
		24 Air Regiment (at Heito)
			36 Ki-27 Nate

References

Bradley et al. (1992)

Francillon (1979)

Morton (1953)

Rottman (2005)

Rottman and Takizawa (2005)

Willmott (1982)