Technical Manual, U.S. War Department, October 1, 1944
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Chapter VIII: Supply, Movements and Evacuation
Section II: Movements
1. SEA TRANSPORTATION. a. General. Various means of sea transportation, depending upon existing conditions and circumstances, are employed by the Japanese Army for troop movements. Cargo and passenger vessels, some converted to troop carriers, from 3,000 to 10,000 tons, are used for basic transportation; frequently, ships of less than 3,000 tons are employed. In one theater of operations "sea trucks" and various types of barges have been used for short runs. In extreme, cases and under adverse combat conditions, reinforcement, maintenance, and evacuation are accomplished by means of warships such as cruisers, destroyers, and submarines.
b. Regular transport and cargo vessels. (1) Shipping Measurements. Several types of tonnage are used to denote the size of a ship or its cargo carrying capacity, namely, gross registered, net, deadweight, displacement, and measurement tonnage. An explanation of these measurements is given below:
(a) Gross registered tonnage (GRT), or simply gross tonnage is the entire inclosed space of a ship expressed in units or "tons" of 100 cubic feet.
(b) Net tonnage is the ship's volume of useful cargo space in units of 100 cubic feet.
(c) Displacement tonnage is the weight of the water displaced by the ship in tons of 2,240 pounds (long tons). Displacement loaded is the weight of the water displaced by a fully loaded ship including cargo, passengers, fuel, water, stores, dunnage, and other items necessary for use on a voyage. Displacement light is the weight of the water displaced by the ship minus the items listed above. Displacement tonnage usually is used to designate the size of naval vessels and only rarely that of cargo or passenger ships.
(d) Deadweight tonnage is the ship's total carrying capacity, expressed in long tons, and represents the difference between displacement loaded and displacement light. The effective pay load of an average cargo vessel is 80 percent of its deadweight tonnage.
(e) The shipping or measurement ton is a volume of 40 cubic feet. The size of Japanese ships usually is given in gross tons. There is no absolute relationship between the gross tonnage of a ship and its cargo carrying capacity. However, as an approximation, it may be assumed that for an average cargo ship the effective deadweight tonnage is equal to its gross tonnage multiplied by a factor of 1.5.
(2) Tonnage requirements. The amount of tonnage required to transport troops will depend upon the type of units transported; the amount of cargo: and the type of loading used; i.e., commercial, combat, organizational, or convoy. The following figures may be used as a guide:
In moving large bodies of troops and their usual impedimenta, over long distances where proper loading facilities are available and cargo can be stowed with the least loss of space, an estimated average of 5 gross tons per man will be required. Such conditions will prevail in moving troops from home ports to theaters of operation. The following table gives the amount of estimated tonnage required to transport various units:
A division with a proportion of Army Troops is estimated to require 125,000 tons when making a long haul. In moving troops within the theaters of operations, particularly where opposed debarkation may be expected, or where rapid unloading is of paramount importance, light loading is employed. Thus in Rabaul-Guadalcanal movements tonnage figures averaged about 9.0 gross tons per man. The following chart is an example of this latter type of loading for various ships in a convoy:
(3) Convoys. Ships carrying troops usually assemble at a predetermined point, where convoys consisting of at least five ships are formed. These then proceed under a naval escort directly to their final destination, or to a staging area for transshipment to the theaters of operation. For illustration of convoy, see figure 158.
(4) Speed of convoys. The speed of convoys depends on the speed of the slowest ship in the convoy and on the extent of and on the extent of zigzagging. Average speed is estimated at 200 nautical miles per 24 hours; small convoys of fast ships may average a speed as high as 15 knots.
(5) Escort of convoys. Convoys are escorted most frequently by destroyers or smaller escort vessels. A convoy of 10 ships usually is accompanied by 3-4 destroyers, but larger or more important convoys may have heavier protection. Convoying distances will vary according to the safety of the passage. Changes of escorts may take place at intermediate points, particularly where a convoy passes from one patrolling area to another.
(6) Loading and discharging. Japanese are expert at handling ships and have achieved a considerable degree of efficiency in loading and discharging military cargo. The rate of loading and discharging will depend on many factors, such as availability of piers, cranes, trained stevedores, etc. It is estimated that in well equipped ports loading and unloading of a ship combat-loaded averaging 5,000 gross tons, using shore or ship's gear, could be accomplished in 3 days (operating 24 hours a day). Where piers are not available, but an adequate number of Motor Barges (MLC) can be utilized, the same rate could be achieved for combat-loaded ships. Where lighters have to be used, as many as 6 days may be required to unload a ship. Harbor congestion or lack of an adequate number of lighters and stevedoring crews may extend the required time to several weeks. General cargo can be unloaded at an average rate of 1,500 long tons per 24-hour day at piers or with MLC, and at 800 long tons per 24-hour day by lighters.
c. Transport by small craft, "sea trucks", and barges. (1) Sea trucks. These are small coastal cargo boats, luggers, and the like, generally stack aft, and varying in size from 120 to 1,000 gross tons. To these may be added latest types of wooden craft (100-300 gross tons) now being built by the Japanese on a large scale. These vessels are chiefly employed in combat zones and for coastal and inter-island transport. They can navigate in shoal waters, can be easily concealed along the coast, and generally are well adapted for the transport of small bodies of troops.
(2) Barges. In view of the danger of attack on large vessels in close waters, the Japanese Army has used landing barges extensively in the Southwest Pacific area for the transport of troops and supplies. They travel by night over set routes and hide during the day in small coves or along a stretch of coast overhung by trees. Figure 157 shows the characteristics and capacities of the barges and small transport craft used in a supply and replacement role.
d. Transport by naval vessels. (1) Cruisers may carry an average of 300 to 400 troops on long runs, and perhaps as many as 1,500 or more on short ones, but few instances of the latter type have been noted.
(2) Destroyers have been used extensively in the Southwest Pacific Area for reinforcement, evacuation, and supply. Their employment as carriers usually is limited to extremely urgent cases. Such trips are short and usually made at night with loads varying according to circumstances. An average load for a 1,500-ton ship may be assumed to be 200-300 troops with some equipment or stores. On some occasions destroyers were known to have towed barges loaded with troops.
(3) Submarines are constantly employed to carry supplies and small parties of troops. Average capacity of submarines is 10 to 15 men plus stores, in addition to their crew. I-class submarines are reputed to be able to carry 50 troops and 20-40 tons of cargo, depending on whether deck cargo is carried and large submarines were reported to have carried as many as 100 troops. For transport by naval vessels, see figure 159, page 182.
2. RAIL TRANSPORTATION. a. General. (1) Japan, proper. The Japanese have considerable experience in rail transportation, both in Japan proper and on the Asiatic continent. Their railroad system is well managed, and their rolling stock is normally in good repair. Honshu, the main island, is encircled by the principal trunk lines, and the interior is well traversed with branch lines and a few trunk lines. The other prominent islands of Japan proper, Hokkaido, Shikoku, and Kyushu are also well served with railroad transportation. The rolling stock of Japan proper is estimated to consist of 6,300 locomotives, 120,000 freight cars, and 16,000 passenger cars.
(2) Korea. The railroads on the Korean peninsula run in a generally north-south direction and link the chief Korean ports with the Manchurian railroad net. There are several east-west connecting lines. The rolling stock in Korea is estimated at 600 locomotives, 7,500 freight cars, and 1,500 passenger cars, exclusive of rolling stock used on approximately 670 miles of narrow gauge railroads.
(3) Manchuria. The Manchurian railroad system, which is characterized by a series of parallel and inter-linked north-south and east-west lines, is built mainly around the South Manchurian Railways' double-tracked Dairen-Harbin line. The Manchurian rail net connects with the Korean system at five points and with the North China system at three points, while numerous strategic lines have been built to the Manchurian-Russian border.
(4) Gauge. The gauge in Japan proper is 3 feet 6 inches, while in Manchuria and Korea, except for a few narrow gauge lines in the latter, it is standard (4 feet 8 1/2 inches).
(5) Capacity. The average load capacity of freight cars in Japan proper is 13 tons, in Manchuria 35 tons, and in Korea 30 tons. In actual movement of freight, it generally may be assumed that the Japanese freight car capacity is half that of freight cars used in the United States. In Manchuria and Korea the capacity would be the same as for similar American freight cars. Third class passenger cars have a seating capacity of 64 passengers in Japan, while in Manchuria and Korea they accommodate from 80 to 100 passengers.
b. Troop trains. (1) Composition of trains. In Japan proper, military trains on the main trunk lines may consist of as many as 35 cars, while smaller trains which must be used on branch lines reduce the number of cars to as low as 20. In Manchuria and Korea military trains average 27-30 cars each. So far as it is practicable, complete units travel as such in separate trains: the composition of the train will vary depending on the type of material belonging to the unit. Officers usually travel in first or second class passenger cars (coaches); other troops travel in third class passenger cars (coaches) or freight cars used temporarily for troop movement. Livestock cars are used for horses; box cars for supplies; and flat cars for vehicles, tanks, and guns.
(2) Dispatch and speed. Troop trains can be dispatched at the rate of one every hour on the main trunk lines in Japan and Manchuria; on the branch lines the rate of dispatch will vary between 10 and 15 trains a day, depending on siding facilities. About 15 miles an hour is the average estimated speed of troop trains on the principal trunk lines in Japan, while in Manchuria it is about 20 miles an hour. On branch lines, the average speed is reduced to 10 to 12 miles an hour.
(3) Loading. In Japan proper, a flat car will carry one 75-mm gun and two caissons; a gun tractor, limber, and gun; two large vehicles; or a large vehicle and two motorcycles. In Manchuria and Korea, the loading may differ only slightly from practices in the United States, since much of the rolling stock was purchased in the United States or followed American standard of construction. The box cars used for troop movements will accommodate between 50 and 60 men. Equipment, when loaded, is secured by blocks and ropes and usually covered by canvas. End, as well as side, ramps are used in loadings and if necessary, ramps are carried by the unit moving by rail. In Japan, entraining ordinarily can be accomplished in 1-1.5 hours, while detraining may be done in less than an hour. For movements in Manchuria or Korea, the time required would be about the same as elsewhere where standard railroad equipment is Used.
(4) Illustrations. Troop movements in Japan and Manchuria are shown in individual tables below, followed by comparative figures of the estimated number of cars required for rail movements in these two regions.
3. MOTOR TRANSPORTATION. a. General. The Japanese have several types of trucks, varying in carrying capacity from 3/4 ton to 3 tons. The most common type called the Nissan, is of 1 1/2 tons carrying capacity. In most data on motor transport movements it will be found that calculations usually are based on the employment of the 1 1/2 ton truck. For capacity of trucks, see figure 163.
b. Requirements. Motor transport required for moving of troops is as follows:
(1) Estimate based on 1 1/2-ton capacity trucks.
(2) Unit combat and field trains included.
(3) Horses and vehicles excluded.
(4) For moving horses and vehicles, it is estimated that, generally, the additional number of trucks required would be equal to the number needed for moving troops and combat equipment.
4. MARCH TABLES AND ROAD SPACES. a. General. The Japanese Army, in its training, has for years stressed marching, and the ability to make long marches. This has resulted in the marching ability shown in Malaya, Burma, and the Pacific islands where Japanese columns have made 10-12 miles per day through heavy jungle and over terrain considered impassable. In New Guinea, a Japanese column, burdened by its heavy weapons, averaged 8-9 miles a day along jungle trails. Jungle marches are ordinarily made on a basis of 20 minutes marching and 20 minutes rest.
b. Marching ability of the various arms. See figures 164 and 165.
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