Japanese Special Naval Landing Force — World War II

In the Japanese language, they were called Kaigun Tokubetsu Rikusentai (海軍特別陸戦隊).  In our language, they were the Imperial Japanese Special Navy Special Landing Forces.  Americans tended to compare these troops to U.S. Marines, but the association is inaccurate.  It is true that they specialized in amphibious landings and the defense of coastal areas, but they were not marines.  They were sailors, led by naval officers, and trained as light infantry.

Japanese SNLF also had a different combat history.  The Japanese avoided assaults on heavily defended positions, attempting instead to leapfrog their opposition and land supplies and reinforcements as quickly as possible — preferably elements of the Imperial Japanese Army.

It was not particularly effective as a process, given the results of their first encounter with U.S. Marines at Wake Island.  While the American Marine garrison at Wake Island was eventually overwhelmed and defeated after fifteen days of a stout defense, those 339 U.S. Marine combat infantry and artillery troops and 50 naval aviators killed 341 Japanese naval infantry. They wounded another 65 — totaling 406 Japanese casualties out of a landing force of 450 men.

American Marines also destroyed 2 Japanese destroyers, sank one submarine, wrecked two patrol boats, and shot down ten aircraft.  This was at a time early in the war when the Japanese had nearly complete freedom of movement in the Pacific Ocean Area, and American troop levels were low.

U.S. Marines would, in time, experience heavy casualties during battles for the Central Pacific.  Until the Solomon Islands campaign early in the war, the only large-scale amphibious landings the American Marines made were training exercises off the coast of Puerto Rico in the 1920s and 1930s.  Small-scale landings have been part of Marine Corps life since its creation in 1775.  In contrast, the Japanese SNLF was a relatively recent development in the Japanese Navy.  From 1897, Japanese warships set aside a percentage of their crew (usually less than a third) as landing force troops (Rikusentai).

These Japanese sailors were trained and equipped with small arms for duty ashore.  Such shore parties were during the Russo-Japanese War (1905) and against Germans in the First World War.  But their most extensive use was in China, where they served on semi-permanent garrisons — such as the garrison at Shanghai after 1927.  The Shanghai Naval Party soon developed a close connection with Japanese (civilian) paramilitary forces in Shanghai. 

The Imperial Japanese Army and Navy were not models of cooperation. While service rivalry is a fact of life in all militaries, all such paled compared to those of the IJA and IJN.  There were several reasons for this “self-defeating” competition.

The Background

Following the Boshin War (1868 – 1869), the Imperial Japanese Army and Navy selected their leaders from the most prestigious Imperial clans of the Imperial.  For the army, post-feudal leaders came primarily from Satsuma and Choshū; naval leaders primarily came from Tosa.  Factionalism was bound to arise because the leaders of the different branches were mostly men from traditionally competing clans.

During the Meiji Restoration, the Emperor divided the War Ministry into Army and Navy departments.  He made the Army the senior of the two and appointed a senior army officer to head the War Ministry.  The Minister of War made final decisions concerning matters affecting the Navy.

The Meiji government was strapped for cash, and the War Ministry seemed to provide more funding to the Army than the Navy.   The funding issue was a constant source of bickering — a situation that lasted well into the twentieth century despite ever-increasing military spending as a percentage of gross domestic product (GDP).  Throughout the ministry’s early development, both branches usually agreed about who their enemy was, but that changed in the 1920s.

The Imperial Japanese Army always saw Imperial Russia (later, USSR) as the greatest threat.  The Navy viewed the United States as the most likely enemy.  These disagreements were known as Hokushin-ron (Northern Road) and Nanshin-ron (Southern Road).  With the Army’s influence in the War Ministry, the Northern Road policy took precedence until 1939, after the Soviet-Japanese border conflicts in Manchukuo (February – September).  After that, the Southern Road policy became Japan’s priority.

After 1939, the Navy and Army became unusually cooperative in developing amphibious warfare doctrine, holding joint exercises in 1922, 1925, 1926, and 1929.  The lessons learned from these exercises were incorporated into the Outline of Amphibious Operations in 1932, which became Japan’s bible of amphibious warfare.  In February 1932, the Japanese landing at Shanghai clashed with Chinese Nationalists (Kuomintang) forces and took heavy casualties.  The IJN responded by authorizing two permanent specialized landing formations on 1 October 1932 — and these became the Special Naval Landing Force.[1]

SNLF Organization

Although historical sources could be more consistent on this matter, there are some indications that only one of the two authorized landing units was formed.  It became known as the Shanghai Rikusentai.  It had a unique table of organization that, by the spring of 1945, had a strength of 3,645 officers and men, was heavily armed with anti-aircraft weapons, and had a platoon of tanks.

The Naval Ministry authorized four additional units late in 1936, one for each Japanese naval district (Yokosuka, Kure, Sasebo, and Maizuru).  Unlike the Shanghai force, which was roughly equivalent to a regiment in strength, district forces were organized as battalion-sized organizations with an authorized strength of 539 officers and men, including two rifle companies and supporting elements.

Each Japanese SNLF rifle company consisted of four rifle platoons and a machinegun platoon.  Each rifle platoon had four 9-man squads; the machine gun platoon had three machine gun squads and an ammunition-bearing squad.  No weapons were heavier than a medium machine gun, and units were trained for unopposed landings.

Following the escalation of hostilities in Shanghai in August 1937, the IJN organized additional SNLF battalions, often organized for a specific task, and then disbanded.  These Task Organizations were highly variable but generally retained the structure of two rifle companies and a machine gun company.  In addition to the Shanghai SNLF, three SNLFs were formed and remained active throughout the war.  These included the 8 Sasebo (with five rifle companies and a gun company), 4 Yokosuka (with five rifle companies of six platoons each), and 1 Maizuru (with 1,316 officers and men organized into six rifle companies of five platoons each).  These three SNLFs were large in personnel but lightly armed and lacked a specific mission in the Pacific naval war.  They remained on Hainan Island (in the Tonkin Gulf) throughout World War II.

In December 1937, the Naval Ministry authorized a structure for a combined headquarters element for two additional SNLFs.  A cadre headquarters needed supporting staff, which soon proved inadequate. 

On July 12, 1939, the IJN published the Naval Landing Force Regulations.  The regulations attempted to standardize SNLF regulations and protocols and provide for a combined SNLF headquarters with supporting elements adequate for its role.  A standard landing force numbered 1,069 officers and men and was fully triangular, with three rifle companies, an artillery company, and various supporting elements.

Updated rifle companies had a headquarters platoon, three rifle platoons, and a machine gun platoon.  Each rifle platoon had three squads and a grenade squad armed with Type 89 Knee Mortars.  The artillery company had two 70mm Type 92 howitzer platoons and two 75mm Type 41 mountain gun platoons.  The SNLF also had three squads of engineers.  Because the SNLF lacked the supply train of equivalent Army units, the Naval Ministry authorized a greater ammunition allocation.

The new regulations also provided for special mountain guns, tanks, and chemical warfare companies that could be attached to an SNLF as needed.  The special mountain gun company was equipped with the more powerful 75mm Type 94 mountain gun.  It could either replace the normal artillery company in an SNLF or serve as a central artillery unit for a combined SNLF.  The special tank company comprised a light tank platoon and three medium tank platoons.  Additional tables of organization for a bewildering variety of gun companies were published shortly after the July 12, 1939 regulations.  The effect was that each naval district organized its SNLF as it saw fit.

By the time of the Japanese attack at Pearl Harbor, twelve such battalion-sized forces were organized.  As the war progressed and SNLFs more frequently found themselves in a defensive role, their armament shifted towards more machine guns and artillery (typically 46 machine guns, 8 120mm coastal defense guns, 16 80mm antiaircraft guns, 4 75mm antiaircraft guns, and a handful of light antiaircraft and antitank guns).  Two or more SNLFs could be combined to achieve a strength roughly equal to a regiment.  A naval commander typically led an SNLF, while a captain or rear admiral led a Combined Special Naval Landing Force.

Conclusion

The SNLF did not share the American Marine’s reputation for toughness.  Two SNLFs were trained for parachute operations, and all had training in amphibious assault operations.  They were specifically trained to be ruthless.  In Southeast Asia, SNLF units committed several atrocities, including the massacre of prisoners of war.

Allied intelligence rated the US and British infantry training and tactics as substandard to that of the Japanese Army — but the U.S. Marines disagreed.  No Japanese unit was better trained or equipped than the U.S. Marine Corps.  Where the Marines did agree with allied assessments, which served no real purpose, was that the SNLF was better trained than the Imperial Japanese Army.  The Japanese Navy may not have agreed with the American Marines.  Among the IJN, their “Marines” were simply sailors with ground combat duties. As Japan lost the initiative in the Pacific, the IJN replaced the SNLF with their Base Force (konkyochitai) (also, Special Base Force) — an echelon prescribed as a defense force for a defined area.  The Base Force consisted of headquarters personnel, heavy coastal artillery, medium anti-aircraft artillery, and subordinate guard forces (keibitai).  These units were often “hastily organized” and inadequate for defending islands against the onslaught of the U.S. Marines.

Endnote:

[1] Although historical sources could be more consistent on this matter, there are some indications that only one of the two authorized landing units was formed.  It became known as the Shanghai Rikusentai.  It had a unique table of organization that, by the spring of 1945, had a strength of 3,645 officers and men, was heavily armed with anti-aircraft weapons, and had a platoon of tanks.

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