were a part of the

Japanese Special Attack Units During World War II, , also called ''shimbu-tai'', were specialized units of the Imperial Japanese Navy and Imperial Japanese Army normally used for suicide missions. They included ''kamikaze'' aircraft, '' fukuryu'' frogmen, and several types o ...

prepared to resist the invasion of the Home islands by Allied forces. The name literally means "crouching dragon," and has also been called "

suicide Suicide is the act of intentionally causing one's own death. Mental disorders (including depression, bipolar disorder, schizophrenia, personality disorders, anxiety disorders), physical disorders (such as chronic fatigue syndrome), and ...

divers" or "

kamikaze , officially , were a part of the Japanese Special Attack Units of military aviators who flew suicide attacks for the Empire of Japan against Allied naval vessels in the closing stages of the Pacific campaign of World War II, intending to ...

frogmen A frogman is someone who is trained in scuba diving or swimming underwater in a tactical capacity that includes military, and in some European countries, police work. Such personnel are also known by the more formal names of combat diver, com ...

" in English texts.

Personnel

Six thousand men were to be trained and equipped with self-contained diving gear including a diving jacket and trousers, diving shoes, and a diving helmet fixed by four bolts. They would be weighed down with of

lead Lead is a chemical element with the Symbol (chemistry), symbol Pb (from the Latin ) and atomic number 82. It is a heavy metals, heavy metal that is density, denser than most common materials. Lead is Mohs scale of mineral hardness#Intermediate ...

and be sustained by liquid food and an air purification system with two 3.5-liter bottles of oxygen at . They were expected to be able to walk at a depth of , for a period of up to ten hours. Personnel were organized into six-man squads with five squads to a platoon, five platoons plus a maintenance platoon to a company, and three companies to a battalion of approximately 540 men. The 71st Arashi was headquartered at

Yokosuka is a city in Kanagawa Prefecture, Japan. , the city has a population of 409,478, and a population density of . The total area is . Yokosuka is the 11th most populous city in the Greater Tokyo Area, and the 12th in the Kantō region. The ...

with two trained battalions and four battalions in training. The 81st Arashi at

Kure is a port and major shipbuilding city situated on the Seto Inland Sea in Hiroshima Prefecture, Japan. With a strong industrial and naval heritage, Kure hosts the second-oldest naval dockyard in Japan and remains an important base for the Japan ...

was planned for 1000 men to be trained by 250 men from Yokosuka. A similar 1000-man Kawatana unit was planned for

Sasebo is a core city located in Nagasaki Prefecture, Japan. It is also the second largest city in Nagasaki Prefecture, after its capital, Nagasaki. On 1 June 2019, the city had an estimated population of 247,739 and a population density of 581 persons p ...

Weapon

Men were to be armed with a Type-5 attack mine containing of

explosives An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...

, fitted to a

bamboo Bamboos are a diverse group of evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, ...

pole. While concealed underwater, men, expecting to be killed by the resulting explosion, would use the pole to push the contact-

fuze In military munitions, a fuze (sometimes fuse) is the part of the device that initiates function. In some applications, such as torpedoes, a fuze may be identified by function as the exploder. The relative complexity of even the earliest fuze de ...

d explosive against the hull of a landing craft passing overhead. Off each potential invasion beach, an inventory of mines was anchored to the bottom for use by the submerged men. Three strings of mines were fifty meters apart, and men would be stationed sixty meters apart, staggered so there would be a man for each 20-meter length of beach.

Concept

Surprise was essential to avoid comparatively simple anti-personnel explosive countermeasures previously used to discourage Italian frogmen in the Mediterranean. Experiments were conducted with underwater foxholes of concrete pipe with steel doors. Preliminary tests with dogs indicated these foxholes would reduce the effects of nearby explosions. Plans were made for larger reinforced concrete stations capable of sheltering six to eighteen men. These larger stations would have been manufactured ashore in a variety of shapes to avoid detection, and then sunk at depths of less than fifteen meters. The Fukuryu were part of a three-stage system of mines including an offshore row of bottom mines to be released by trip wires to float up under passing landing craft, and rows of stationary magnetic and contact-fuzed mines in shallow water closer to the beach. Fukuryu

Implementation

One thousand diving suits were ready by 15 August 1945, and eight thousand more had been ordered. Yokosuka had 450 suits, and both Kure and Sasebo had sixty suits. None of the planned ten thousand Type-5 attack mines had been completed, but four hundred dummy mines had been produced for training. Several deaths occurred during training due to malfunctions. Only twelve hundred men had been trained when Japan surrendered before the invasion of the Japanese mainland occurred. There are reports of some strikes that allegedly made use of similar

military tactics Military tactics encompasses the art of organizing and employing fighting forces on or near the battlefield. They involve the application of four battlefield functions which are closely related – kinetic or firepower, mobility, protection or se ...

: *The infantry landing craft (gunboat) LCI(G)-404 was damaged by suicide swimmers in Yoo Passage, Palau Islands, on January 8, 1945. *Some Japanese suicide swimmers attempted an attack upon the surveying ship in Schonian Harbor, Palau Group, on February 10, 1945.

References

External links