Reconnaissance regiments (Japan)

The Reconnaissance regiment (Sōsaku-rentai (搜索聯隊) or Sōsaku-tai (搜索隊)) in the Japanese language was a type of military establishment within the Imperial Japanese Army during the 1940-1945 period. Derived from the Cavalry regiment, the Reconnaissance regiment was tasked with combat scouting. In Japanese military literature, the term reconnaissance regiment is commonly abbreviated as SO. These regiments were often attached to numerous Japanese divisions during the initial stages of the Pacific War. In contemporary Japan, these regiments are analogous to Reconnaissance battalions within the divisions of the Japan Ground Self-Defense Force.

Historical background
During the Second Sino-Japanese War, Japanese military commanders frequently faced challenges requiring reconnaissance, rapid message transfer, and the utilization of maneuver warfare advantages. These tasks were typically carried out by cavalry regiments within the Japanese army (see Japanese cavalry regiments). However, the widespread adoption of the machine gun during the First World War revealed the significant vulnerability of horseback troops against defensive positions. Simultaneously, the rapid expansion of automobile production led to numerous experiments with motorized and mechanized cavalry units worldwide.

While Japan initially retained cavalry regiments and battalions, the introduction of the first batch of seven Sōsaku-tai (reconnaissance regiments) occurred in 1937-1938 as part of a significant army reorganization preceding the Pacific War. These units were later renamed as Sōsaku-rentai. By 1940, existing cavalry regiments had also been reorganized into reconnaissance regiments, although some cavalry units were retained. Notably, the Imperial Guard division maintained its cavalry regiment alongside a reconnaissance regiment. Additionally, the 3rd, 6th, 25th, and 26th cavalry regiments remained unchanged until the end of the Pacific War.

The cavalry regiment within the Imperial Guard division included an armoured car company, and many cavalry regiments unofficially acquired tanks, even after the formation of the 1st Tank Division (Imperial Japanese Army).

Problems with concept
While the Reconnaissance regiment was designed to integrate both Armoured fighting vehicles and Motorized infantry, the initial availability of vehicles for the army was limited. This occurred because vehicles like the Type 92 Heavy Armoured Car tankette, Type 94 tankette, and Type 97 Te-Ke tankette, intended for reconnaissance, were also tasked with combat roles and absorbed into tank regiments. Additionally, although the initial concept of the Reconnaissance regiment envisioned it as a self-sufficient combat force, in practice (particularly during the Battles of Khalkhin Gol), mechanized forces were primarily used to reinforce under-equipped infantry units. Consequently, the supply of armoured vehicles proved to be grossly inadequate.

With the adoption of the Nanshin-ron strategy for the Pacific War, reconnaissance regiments initially saw success during the Japanese conquest of Burma. However, as operations shifted towards smaller islands, the limitations of light armoured vehicles became evident. This led to the frequent deployment of infantry forces to outlying islands while reconnaissance regiments remained on the mainland. Consequently, many reconnaissance regiments were disbanded as unnecessary, and personnel were reassigned to tank units. Although the Japanese army initially fielded 40 reconnaissance regiments, only 23 remained by the war's end, with 9 of them significantly under-strength.

Orders of battle
Reconnaissance regiments were small-scale units, typically comprising about 500 men in total. As a result, they did not have battalions in their structure and were usually commanded by a Major, rather than a Colonel, as was typical for infantry regiments. The variation in the order of battle between regiments, and even within the same regiment at different times, was significant. Furthermore, the regiment was often tailored to fit into the available transport ship.

Order of battle (1937-1938)

 * Headquarters
 * Cavalry squadron
 * Armored car company - 5 x Type 92 Heavy Armoured Car tankette or other available tankettes

Order of battle (1939-1941)

 * Headquarters
 * Cavalry squadron
 * Motorized infantry company (with Type 94 6-Wheeled Truck, Type 95 reconnaissance car and other vehicles)
 * Armored car company - 5-8 x various armored cars or tankettes (based on availability)

Order of battle (1942-1945, of infantry division)
This is the typical wartime reconnaissance regiment (with the most typical being the 2nd and 16th regiments). Compared to earlier versions, it has part of its horses replaced by Type 97 motorcycles.


 * Headquarters
 * 1st Cavalry squadron
 * 2nd Cavalry squadron
 * 1st Armored car company - 8 x tankettes
 * 2nd Armored car company - 8 x tankettes
 * Signals platoon

Order of battle (1942-1945, of tank division)
The first three tank divisions had the reconnaissance regiment attached. Due to a lack of Japanese self-propelled guns, these were frequently substituted with Type 97 Chi-Ha medium tanks or even light tanks.


 * Headquarters
 * 1st Light Tank Company - 10 x Type 95 Ha-Go or other light tanks
 * 2nd Light Tank Company - 10 x Type 95 Ha-Go or other light tanks
 * 3rd Light Tank Company (optional) - 10 x Type 95 Ha-Go or other light tanks
 * Cavalry squadron
 * Self-propelled artillery company - 10 x Self-propelled gun and 2 x Type 95 Ha-Go or other light tanks
 * Maintenance company

23rd division
During the Battles of Khalkhin Gol, the reconnaissance regiment of the 23rd Division was newly organized. During the Japanese advance in July 1939, it was tasked with cutting off the retreat route of the Soviet army. Although it reached its designated position, the failure of other units resulted in the regiment being surrounded and wiped out. Immediately reorganized, it was used to reinforce the Japanese defense at 47.89°N, 118.58°W (Fui Height). Notably, the reconnaissance regiment was the only unit able to retreat from the height after running out of ammunition and food (all other troops were annihilated), and the regiment commander (Ioki Sasaki) pleaded guilty to unauthorized retreat before a court-martial.

56th division
During the early stages of the Japanese conquest of Burma, the reconnaissance regiment of the 56th Division played an active role at the spearhead of the advance. The regiment landed in Yangon on March 26, 1942, and swiftly occupied Taungoo, 220 kilometers away, by April 1, 1942. Subsequently, a motorized infantry company and an engineer (bridging) company headed north, reaching Bhamo on May 4, 1942, after traveling over 1400 kilometers.

Battle of Leyte
The reconnaissance regiment of the 1st Division, reduced to a headquarters, infantry company, and machine gun platoon without any vehicles (comprising about 200 men in total), landed in Ormoc in late November 1944. After receiving horses and tanks from the 2nd Division, it occupied mountain-top positions and successfully defended critical passes for over a month against the 24th Infantry Division (United States). Despite other Japanese units in the vicinity beginning to retreat, the order to retreat encountered difficulties reaching the reconnaissance regiment, resulting in only 45 members of the regiment surviving.

References and future reading
This page includes content from the Japanese Wikipedia page Reconnaissance regiment, accessed on January 22, 2016.