1. INTRODUCTION

Although the Japanese have gained considerable experience in the use of smoke in China, they have used it very little to date against United Nations forces in the Southwest Pacific.

The Japanese are known to possess several types of smoke-producing equipment and to have personnel trained for smoke operations. Temporary smoke companies (infantry regimental smoke units) are formed from infantry regimental personnel (3 to 10 men from each company) who have been trained in chemical warfare duties. These men perform ordinary company duties except when detached for chemical warfare services. The enemy also has field gas companies (each about 220 strong), which are allotted to divisions for specific operations. Each of these companies carries 3,240 smoke candles. (Whether they are toxic, the ordinary type, or include both, has not been reported.) When the use of smoke is planned on a large scale, these smoke companies may be formed into temporary smoke battalions—probably three companies to the battalion.

Various types of Japanese smoke-producing equipment—including smoke candles, a rifle smoke grenade, and grenade-discharger smoke grenades—have been reported by the Intelligence Branch of the U. S. Chemical Warfare Service. Reports on these items of equipment constitute the major part of this section.

2. TYPE 99 SELF-PROPELLED SMOKE CANDLE

This candle consists of three main parts: an outer cylinder 8 inches long and 2 inches in diameter, an inner container (which is the candle proper), and a propelling charge.

One report states that the candle is painted light gray, with a white sighting line along the side, whereas another report states that it is olive drab in color. Both reports give the total weight as 2.8 pounds, including the smoke mixture, which weighs 1.41 pounds. The mixture consists of hexachlorethane, 56.5 percent; zinc dust, 30 percent; zinc chloride, 2.8 percent; and zinc oxide, 10.7 percent.

To operate the candle, the top and bottom slip-on covers (sealed with adhesive tape) are removed, and the candle is placed in an inclined position by means of an attached spike (see No. 4 of fig. 6), which is slid to the bottom of the cylinder and then pushed into the ground. The fuze (10) is ignited from the match head (3), which, in turn, ignites the propelling charge. The explosion shoots the inner container a distance of 131 to 306 yards, according to the angle at which the spike is driven into the ground. The smoke mixture is ignited by means of a fuze after a delay of 4 to 5 seconds.

Figure 6.—Type 99 Self-propelled Smoke Candle.

3. SMOKE GRENADE (for grenade discharger)

This smoke grenade, about 6 inches long and 2 inches in diameter, is fired from the 50-mm Type 89 heavy grenade discharger.¹ It can be projected a distance of 45 to 206 yards, according to the adjustment of the discharger.

The propellant weighs 4.24 ounces and the detonator .25 ounce—no other weights are given.

Before being used, the grenade is removed from its outer cover. The delayed-action fuze (see No. 4 of fig. 7) becomes ignited from the explosion of the propellant (7), and passes to the powder charge (2), which ignites the smoke mixture (1).

Figure 7.—Smoke Grenade (for grenade discharger).

4. TYPE 94 SMOKE CANDLE (Small)

The container of this candle is 7.25 inches long and 2.1 inches in diameter, and is painted green. The markings (see No. 15 of fig. 8) show the usual details of the date and place of manufacture. The total weight of the candle is 2.17 pounds, including the smoke-producing (Berger-type) mixture. The mixture itself weighs 1.87 pounds, and consists mainly of carbon tetrachloride, zinc dust, and zinc oxide.

In operation, the sheet-iron cup (6) burns off with the igniter, and consequently starts the burning of the smoke-producing mixture.

Figure 8.—Type 94 Smoke Candle (small).

5. TYPE 94 SMOKE CANDLE (Large)

This candle is a larger model of the Type 94 described in paragraph 4. It differs mainly in the method of ignition, which apparently is done by means of a cord attached to the igniting apparatus. (See fig. 9.)

The length of this candle is 31.5 inches and the diameter is approximately 3 1/3 inches. The total weight is given as 16.5 pounds, including the smoke-producing mixture (Berger-type) which weighs 15 pounds.

Figure 9.—Type 94 Smoke Candle (large).

6. TYPE 94 FLOATING SMOKE CANDLE (Model B)

This type of smoke candle floats on water by means of an inflated rubber tube. The candle has a supporting ring with two lugs, to which the tube is fastened. (See fig. 10.)

Figure 10.—Type 94 Floating Smoke Candle (Model B).

The candle, painted a dark gray, is 31.18 inches long (792 mm) and 3.11 inches in diameter (79 mm). The total weight of the candle is approximately 12.47 pounds (5,660 grams), and the smoke-producing mixture weighs approximately 10.8 pounds (4,910 grams).

The fuze used is known as the "10th-year pattern hand-grenade time fuze," according to a label on the box in which a fuze was packed. The fuze is removable. It is taken out and carried separately when the candle is transported. The candle itself is sealed by use of the "wing-nut" plug.

The candle may also be supplied with a delayed-action igniter. This igniter is constructed in a manner similar to the "10th-year pattern hand-grenade time fuze," except that the striker and detonator are replaced with a length of ordinary time fuze, one end of which is sealed into the igniter itself. The igniter screws into the candle; it is used when a delay greater than the 4 to 7 seconds delay of the hand-grenade type is required. To ignite the fuze, the Japanese provide a match head in a thin metal tube attached to the other end of the length of fuze.

The smoke-producing mixture is composed of hexachlorethane, 50 percent; metallic zinc, 23.5 percent; and zinc oxide, 26.5 percent.

Details on how to operate the candle are given in a label on the outside of the weapon. A translation of the instructions reads as follows:

7. 10-KG NAVAL SMOKE CANDLE

This candle, painted gray, is approximately 9.5 inches long and 6 inches in diameter. The total weight is 20.5 pounds. A paper name card on top of a captured candle bore the following: "10-kg smoke candle, made . . . 1941."

The candle container, made of iron, is cylindrical in shape and is closed at either end by tin-plate disks. It is made airtight by the soldering of all seams. A single hinged carrying handle (see fig. 11) is riveted and soldered to the container near the top. The igniter apparatus fits into a hole in the center of the top. A wooden plug is provided to fill the hole while the candle is being transported.

Figure 11.—10-Kg Naval Smoke Candle.

This smoke candle is believed to have been designed for use on the rear of a boat or ship, as well as on land. An instruction label on a captured candle stated that it "may be used aboard ship if placed on a sheet of iron."

According to the instruction label, the candle is filled with Berger-type smoke mixture, which, when ignited, gives off an ash-colored smoke for 3 to 4 minutes.

The label also stated that "an ignition apparatus is supplied separately, and is kept in the container. It consists of an ignition peg and a striking plate."

Other instructions given include the following:

a. Methods of Operation

b. Points on Using

c. Instructions for Storage

8. RIFLE SMOKE GRENADE

The rifle smoke grenade is used with a special adapter, which fits over the end of the standard Japanese 6.5-mm rifle barrel. The force to propel the grenade and the primary means of ignition are furnished by the .256-caliber Japanese cartridge (6.5 mm), which is loaded with 1.927 grams of powder and fitted with a wooden pellet. This cartridge is wrapped in paper and stored in the grenade tube.

The grenade, Weighing 1.29 pounds and having an over-all length of 8 1/2 inches, is painted a silver color and thoroughly waterproofed with coats of heavy lacquer and paraffin. The nose and body proper, 2 inches in diameter, are made of tin plate. The base, stamped from sheet steel, is screwed onto the body by means of rolled threads. Four smoke vents are placed at 90-degree intervals around the base, and are covered with light sheet metal disks which are held in place by waterproof cement covered with paraffin. The grenade has three flash ports, spaced at 120-degree intervals in the bottom of the base. (See fig. 12.)

Figure 12.—Rifle Smoke Grenade.

Four fins, made of tin plate, are soldered to, and equally spaced around, the grenade tube. The fins are 2 3/8 inches long and 11/16 of an inch wide; the tube is 1 3/16 inches in diameter.

The smoke-producing mixture, which weighs .6 pound, is composed of the following:

		Percent
Hexachlorethane	_ _ _ _ _	56.2
Zinc dust	_ _ _ _ _	27.6
Zinc Chloride	_ _ _ _ _	2.9
Zinc Oxide	_ _ _ _ _	13.4

9. SMOKE-SCREEN OPERATIONS

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 han (at normal strength a han is roughly equivalent to our squad) were selected for the operations, under direction of a first lieutenant. Each han was given the responsibility for screening a separate area (see fig. 13).

a. Personnel and Equipment

(1) No. 1 Han.—This unit was composed of a sergeant major as leader, another noncommissioned officer, and 20 privates. If was allotted six collapsible boats. If needed, an armored boat or high-speed boat also would be allotted. This han was to use 200 smoke candles of the floating type, 10 of the Type 94 (large), and 160 of Type 94 (small).

(2) Nos. 2 and 3 Han.—Each of these units was allotted a noncommissioned officer as leader, 15 privates, and the following equipment: 100 candles of the floating type, 7 of Type 94 (large), 120 of Type 94 (small), and three collapsible boats.

In addition to the equipment allotted to the above han, the Japanese document stated that 400 of the floating-type candles "are to be kept in readiness" [probably as a reserve].

b. Laying the Screen

Regarding the actual operation, the document included the following:

[A study of the Japanese diagrams (figs. 13 and 14) indicates that, in this operation, the enemy planned to lay a smoke screen over the designated area by placing the floating-type candles at certain intervals in the water, and, if necessary, to operate the Type 94 candles on adjoining land areas.]

Figure 13.—Japanese Smoke-screen Plans.

Figure 14.—Japanese Smoke Laying

c. Care of Candles