Reconnaissance regiments (Japan)

Reconnaissance regiment (Sōsaku-rentai (搜索聯隊) or Sōsaku-tai (搜索隊)) in Japanese language, was the type of the military establishment within Imperial Japanese Army in the 1940-1945 period. Reconnaissance regiment was the type of unit derived from Cavalry regiment, tasked with combat scouting. In Japanese military literature reconnaissance regiment is usually abbreviated by SO letters. These regiments were attached to the large number of the Japanese division at the opening stages of the Pacific War. In modern Japan, these regiments are equivalent to Reconnaissance battalion in the divisions of the Japan Ground Self-Defense Force.

Historical background

During the Second Sino-Japanese War, the Japanese military commanders were frequently challenged with situations requiring reconnaissance, rapid messages transfer and using the advantages of the maneuver warfare. Such tasks in Japanese army were regularly performed by cavalry regiments (see Japanese cavalry regiments). Unfortunately, development and wide usage of the machine gun during First World War have exposed extreme weakness of the horseback-riding troops against any defensive positions. Simultaneously, the rapid expansion of automobile production have resulted in many experiments with motorized and mechanized cavalry across the world. Although in Japan was observed a long retention of cavalry regiments and battalions, in 1937-1938 the initial batch of seven Sōsaku-tai (reconnaissance regiments) was introduced into the army of Japan. These were renamed as Sōsaku-rentai during the great army reorganization leading to Pacific War. Since 1940, the existing cavalry regiments were also reorganized into the reconnaissance regiments. Some cavalry regiments were retained. Most notably, Imperial Guard division have kept cavalry regiment while also including reconnaissance regiment. Also, 3rd, 6th, 25th and 26th cavalry regiments were not reorganized until the end of the Pacific War. It should be noted what in Imperial Guard division cavalry regiment did include an armoured car company, and many cavalry regiments have unofficially hoarded tanks even when the 1st Tank Division (Imperial Japanese Army) was formed.

Problems with concept

While the Reconnaissance regiment was envisioned as combination of the Armoured fighting vehicles and Motorized infantry, initial vehicles available for the army was very sparse. It happened because Type 92 Heavy Armoured Car tankette, Type 94 tankette and Type 97 Te-Ke tankette earmarked for reconnaissance, were also overloaded with attack role, and absorbed into the tank regiments. Also, while initial concept was what Reconnaissance regiment must be a self-sufficient fighting force, in practice (especially during Battles of Khalkhin Gol) the mechanized forces were predominantly used to reinforce under-powered infantry units. Therefore, the supply of Armoured fighting vehicles is turned to be grossly inadequate.

As Nanshin-ron strategy was adopted for the Pacific War, the reconnaissance regiments were initially very successful during Japanese conquest of Burma, but later the operations have become increasingly focused on smaller islands. Because the performance limitations of light armoured fighting vehicles were obvious at this point, the reconnaissance regiments were frequently left behind on mainland while infantry forces have headed to outlying islands. Therefore, reconnaissance regiments have turned unnecessary one after another and disbanded. Personnel was typically re-assigned to the tank units. While at the peak the Japanese army had 40 reconnaissance regiments, by the end of war only 23 remained, of them 9 being significantly under-strength.

Orders of battle

Reconnaissance regiments were a small-scale units, comprising about 500 men in total. Therefore, they did not have battalions in structure, and were usually commanded by Major instead of Colonel as was typical for infantry regiment. Difference in order of battle between regiments and even between same regiment in different times were very large. Furthermore, the regiment was frequently tailored to fit into the available transport ship.

Order of battle (1937-1938)

Order of battle (1939-1941)

Order of battle (1942-1945, of infantry division)

This the typical wartime reconnaissance regiment (most typical being 2nd and 16th regiments), compared to earlier version it has part of horses replaced by Type 97 motorcycles.

Order of battle (1942-1945, of tank division)

First three tank divisions had the reconnaissance regiment attached. Due to lack of Japanese self-propelled guns, these were frequently substituted for Type 97 Chi-Ha medium tanks or even for light tanks.

Notable military operations

23rd division

During the Battles of Khalkhin Gol the reconnaissance regiment of the 23rd division was just organized.　During Japanese advance in July 1939, it was responsible for cutting the retreat route of the Soviet army. Although it reached designated position, failure of other units has resulted in regiment being surrounded and wiped out. Immediately reorganized, it was used to augment Japanese defense at 47°53′N 118°35′E / 47.89°N 118.58°E / 47.89; 118.58Coordinates: 47°53′N 118°35′E / 47.89°N 118.58°E / 47.89; 118.58 (Fui Height). Notable, reconnaissance regiment was only unit who was able to retreat from height after running out of ammunition and food (all other troop were annihilated), and regiment commander (Ioki Sasaki) has pleaded guilty for unauthorized retreat before court-martial.

56th division

During the early stages of Japanese conquest of Burma, the reconnaissance regiment of the 56th division played an active role at the spearhead of advance. Regiment landed in Yangon 26 March 1942, and soon Regiment landed to Rangoon on March 26, 1942, and occupied Taungoo 220 km away 1 April 1942. Then, a motorized infantry company and engineer (bridging) company headed north, reaching Bhamo 4 May 1942 after over 1400 km long travel.

Battle of Leyte

The reconnaissance regiment of the 1st division, tailored down to headquarters, infantry company and machine gun platoon without any vehicles (about 200 men in total), have landed in Ormoc in late November 1944. After receiving horses and tanks from 2nd division, it took mountain-top positions and was able to defend the critical passes for over the month against 24th Infantry Division (United States). After all other Japanese units in vicinity have started retreating, the order of retreat had difficulty reaching the reconnaissance regiment, with only 45 members of the regiment surviving as the result.

List of reconnaissance regiments

Number From
data-sort-type="date"		 Comments
Guards 1 July 1940 -
1 1 June 1939 destroyed in Battle of Leyte
2 1 September 1940 -
4 1 June 1942 -
5 1 July 1940 -
7 1 August 1940 -
8 1 June 1939 destroyed in Battle of Luzon
10 1 July 1940 destroyed in Battle of Luzon
12 1 July 1940 -
14 1 July 1940 served with 18th div., returned to 14th div. in 1943
15 1 April 1938 disbanded in July 1940
16 1 July 1940 destroyed in Battle of Luzon
17/1 1 April 1938 disbanded in July 1940
17/2 1 July 1944 formed on New Britain from split 51st recon regiment
19 1 August 1940 merged with 103rd independent brigade in 1945
20 1 July 1940 left as independent unit in Korea
21 1 April 1938 disbanded in May 1941
22 1 April 1938 disbanded in July 1940
23 1 April 1938 used to re-organize division after the Battles of Khalkhin Gol. Destroyed in Battle of Luzon
24 1 November 1939 destroyed in Battle of Okinawa
26 1 September 1937 disbanded in July 1944
27 1 June 1938 disbanded in May 1943
30 1 May 1943 destroyed in Battle of Mindanao
32 1 February 1939 disbanded in May 1941
33 1 February 1939 disbanded in May 1941
34 1 February 1939 disbanded in May 1943
35 1 February 1939 disbanded in May 1941
36 1 February 1939 disbanded in May 1941
37 1 February 1939 disbanded in May 1941
38 1 February 1939 disbanded in May 1941
39 1 February 1939 demobilized after Surrender of Japan
42 1 May 1943 disbanded in April 1944
43 1 May 1943 disbanded in April 1944
46 1 May 1943 disbanded in October 1943
48 1 November 1940 -
50 1 May 1944 soon reinforced 48th recon regiment
51 1 July 1940 provisional unit, split in 1944
53 1 July 1940 -
54 1 July 1940 destroyed in Burma Campaign
56 1 July 1940 -
57 1 July 1940 thought in Soviet invasion of Manchuria
107 1 May 1944 -
119 1 November 1944 -
1(tank) 24 June 1942 transformed into 26th tank regiment
2(tank) 24 June 1942 transformed into 27th tank regiment
3(tank) 24 June 1942 -

References and future reading

This page incorporates material from the Japanese Wikipedia page Reconnaissance regiment, accessed 22 January 2016

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