Japanese Smoke Warfare, WWII Tactical and Technical Trends, No. 27: June 17, 1943 (Lone Sentry)

a. Organization of Smoke Troops

For some years past the Japanese have been engaged in developing the means of employing chemical warfare in their Army and Air Force. They are known to have organized a Chemical Warfare Department with a technical research branch and to have established units of Chemical Warfare troops. However, Chemical Warfare activities in the Japanese Army have been more or less decentralized. It is not known definitely whether there is a separate Chemical Warfare branch of the service similar to that in our Army. A recent report states that there has been created in the Japanese Army a new Chemical Warfare Inspectorate headed by Lt. General Kazumoto Machijiri. A Chemical Warfare school is located at Narashino.

A foreign report, admittedly not verified, states that the Japanese have chemical troops organized into sections, platoons, companies, battalions, and regiments - the latter units consisting of approximately 1,500 men each. This report (January 1941) refers to the 5th and 6th Chemical Warfare Regiments as being the only Chemical Warfare units in China. It is pointed out that from this information one might presume the existence of the 1st to 4th Chemical Warfare Regiments. According to this same report, one of the two chemical regiments in China was at that time reported to be preparing to leave for French Indo-China.

According to a document which appears to be an annex to an operations order, and which the Chinese claim to have captured from the Japanese during combat operations in the vicinity of Anking in June 1938, the Japanese employed chemical units on each flank of their forces. These units were provided with chemical projectors and comprised one company on one flank and one squad on the other flank.

According to a recent report from Chungking, China, the Japanese Army has a Chief of Chemical Warfare and a Chemical Warfare Branch. The tactical unit of the Chemical Warfare Branch is the battalion. To allay suspicion, all chemical units are referred to as "smoke" units. The smoke battalion is a flexible organization with any number of smoke companies above two. Each combat regiment gives special training in gas warfare to selected men. Each regiment is able to form one smoke company of such men. However, the smoke company is not listed as a tactical organization of the regiment. Each regiment has a gas officer.

b. Japanese Smoke Tactics

A translation of a Japanese military training pamphlet on the "Use of Special Smoke" indicates that the Japanese are familiar with the tactical employment of smoke. The translation of this Japanese document states that "It is a short cut to victory to launch vigorous and dashing assaults under the barrage of special smoke, taking good advantage of its effects," and further states that "ordinary smoke may be used to enhance the screening effect of the special smoke." It is pointed out that gas masks should be worn in such cases, and not removed until ordered. The obvious conclusion is that the "special smoke" is toxic.

The principal Japanese weapon for the employment of chemical munitions, according to a reliable foreign report, is the 90-mm mortar type "94" for which a maximum range of 4,155 yards is claimed. It fires a projectile weighing from 11 to 57 pounds. The total weight of this trench mortar is approximately 350 pounds.

Both non-toxic and toxic candles have been used by the Japanese. Non-toxic types include smoke candles and lacrimatory gas candles. (See Tactical and Technical Trends Nos. 7, p. 10 and 21, p. 11.) The former is reported to be filled with a Berger-type mixture of zinc, zinc oxide, and clay-like material, the latter filled with tear gas.

A Japanese handbook on the use of toxic smoke generators enumerates the following points:

(1) Various alternatives are given as to density, and it is stated that generators put down 1 meter apart may affect an area 1,500 meters (1,640 yards) deep. The normal density, however, is given as 2 or 3 rows of generators not less than 20 cm (7 to 8 inches) apart.

(2) The ideal distance of the release line from the enemy is given as 300 meters (328 yards) and the maximum as 500 meters (547 yards).

(3) Generators are not to be employed in daytime unless the weather is dull and the speed of the wind does not exceed 6 to 10 mph. Under such daytime conditions, they may be employed "at short distances."

(4) The value of combining ordinary smoke with toxic smoke is stressed. The advantages claimed are that ordinary smoke will show the direction of the wind before the toxic generators are ignited. This will give the infantry additional cover during their advance.

The same handbook states that the commander of the smoke unit must cooperate with the commander of the unit with whom generators are to be used, and he must reconnoiter. Planning his smoke screen according to the general plan of attack, he must issue orders covering the following points:
       (a) Information regarding enemy and friendly troops
       (b) Location of objective and results desired
       (c) Position of smoke line
       (d) Orders covering meteorological information
       (e) Probable zero hour for ignition
       (f) Disposition to be taken up after ignition
       (g) Pursuit and attack plans
       (h) Transportation orders
       (i) Signal plans for the ignition order.

c. Actual Use of Smoke by the Japanese

In the first battle of Changsha, China, during October and November 1939, the Japanese made very extensive use of smoke screens. They are also reported to have used smoke extensively in operations of all kinds in the attacks in Malaya, but only to a limited extent in the Burma campaign.

Some 200 smoke floats, weighing 22 pounds each and with an emission time of 8 minutes, were reported used in the Japanese landing operations at Anking, in June 1938.

Japanese orders, captured by the Chinese, indicate that 1,300 small generators were to have been used by the infantry together with toxic generators in different sectors, in the ratio of between 1:10 and 4:10, respectively.

The Japanese used steel, floating smoke pots, with a chlorsulfonic acid filling, during the landing operations at Milne Bay in New Guinea.

In August 1936, a Japanese newspaper referred to the development of smoke-forming mixtures capable of functioning in extreme cold (-60 degrees F). The mixture was composed of stannic chloride or antimony pentachloride and titanium tetrachloride.

Japanese plans for the use of smoke to screen the unloading of troops and supplies at and near Lae, New Guinea, are revealed in an enemy document, which is paraphrased below:

Three hans (at normal strength they are roughly equivalent to our squads) were selected for the operations, under the direction of a first lieutenant. Each han was given the responsibility for screening a separate area.

No. 1 han was composed of a sergeant major, another non-commissioned officer, and 20 privates. It was allotted 6 collapsible boats, and if needed, an armored high-speed boat. This han was to use 200 smoke candles of the floating type, 10 of the large "94" type, and 160 of the small "94" type.

Nos. 2 and 3 hans were allotted a non-commissioned officer as leader and 15 privates. They were each equipped with 100 floating candles, 7 of the large "94"-type generators, 120 of the small "94"-type generators, and 3 collapsible boats. In addition to the above equipment allotted to the three hans, 400 floating-type candles were to be kept in readiness.

Regulations for the formation of smoke screens are to be based on orders from Debarkation Unit Headquarters.

When operations begin, all smoke candles are to be lighted at the same time, when the signal shots (red dragon) are fired. The main smoke operations are to be carried out by boats over the designated water area. Smoke operations will also be conducted over land, according to circumstances.

A study of the Japanese diagram shows that in this operation, the enemy planned to lay smoke screens by placing candles on the rear part of boats, and also by placing the floating-type candles at certain designated intervals in the water.

Smoke signaling may be done with the 50-mm mortar, with a vertical range of 100 yards. The following flares have been noted, but their meaning has not been made clear:
       Green hanging star (with parachute)
       Yellow dragon (with parachute)
       Two red stars

*Reprinted from a recent Chemical Warfare Bulletin.