Manual of Military Training, James A. Moss [books under 200 pages .TXT] 📗
- Author: James A. Moss
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Fig. 16
Trench Shelter
1149. Traverses. Fire trenches are divided into sections or bays by means of traverses which intercept side or enfilade fire and limit the effect of shells, bombs or grenades, which burst inside of the trench. The traverses should be wide enough to screen the full width of the trench with a little to spare. The thickness of the traverse varies from 3 to 6 feet or more. Six feet is the dimension generally found in the traverses in the trenches on the European battle fronts.
1150. Trench recesses; sortie steps. It will be noted that in some of the diagrams of the trenches now being used in the European War the berm has been eliminated entirely. The object being to bring the firer closer to the vertical wall thus giving him better protection from shrapnel fire. There have also been added to the trench, recesses for hand grenades. These recesses are similar to recesses dug in the front wall of the trench for ammunition. One form of recess is shown in (Fig. 18). In order to provide facilities for rapidly mounting from the trench to charge, sortie steps and stakes have been provided in some trenches as shown in (Fig. 16).
Store Recesses for Water, Hand-Grenades, Reserve Ammunition, Machine Guns, Range Finders, Blankets, etc. (From Field Entrenchments—Solano.)
1151. Parados. Instead of shrapnel, explosive shell is most frequently used in the European War. This necessitates the addition of a parados to the fire trench to protect against the back blast of high explosives. This is shown in (Figs. 8 and 17).
An interesting development in cover for the firing line is shown in dugouts constructed in the fire trenches in the European war. These dugouts are deep underground and shelter from 3 to 8 men each (Fig. 19). These dugouts will be discussed more in length under cover trenches.
1152. Head cover is the term applied to any horizontal cover which may be provided above the plane of fire. It is obtained by notching or loop-holing the top of the parapet so that the bottoms of the notches or loopholes are in the desired plane of fire. The extra height of parapet may be 12 to 18 inches and the loopholes may be 3 to 31/2 feet center to center.
Head cover is of limited utility. It increases the visibility of the parapet and restricts the field of fire. At close range the loopholes serve as aiming points to steady the enemy's fire and may do more harm than good at longer ranges. This is especially the case if the enemy can see any light through the loophole. He waits for the light to be obscured, when he fires, knowing there is a man's head behind the loophole. A background must be provided or a removable screen arranged so that there will be no difference in the appearance of the loophole whether a man is looking through it or not. Head cover is advantageous only when the conditions of the foreground are such that the enemy can not get close up.
1153. Notches and loopholes, Figs. 20–22, are alike in all respects, except that the latter have a roof or top and the former have not. The bottom, also called floor or sole, is a part of the original superior slope. The sides, sometimes called cheeks, are vertical or nearly so. The plan depends upon local conditions. There is always a narrow part, called the throat, which is just large enough to take the rifle and permit sighting. From the throat the sides diverge at an angle, called the splay, which depends upon the field of fire necessary.
The position of the throat may vary. If on the outside, it is less conspicuous but more easily obstructed by injury to the parapet and more difficult to use, since in changing aim laterally the man must move around a pivot in the plane of the throat. If the material of which the loophole is constructed presents hard surfaces, the throat should be outside, notwithstanding the disadvantages of that position, or else the sides must be stepped as in Fig. 22. In some cases it may be best to adopt a compromise position and put the throat in the middle, Fig. 22. Figs. 23 to 26 show details and dimensions of a loophole of sand bags.
A serviceable form of loophole consists of a pyramidal box of plank with a steel plate spiked across the small end and pierced for fire. Fig. 27 shows a section of such a construction. It is commonly known as the hopper loophole. The plate should be 3/8 in. thick, if of special steel; or 1/2 in., if ordinary metal. Fig. 28 shows the opening used by the Japanese in Manchuria and Fig. 29 that used by the Russians.
The construction of a notch requires only the introduction of some available rigid material to form the sides; by adding a cover the notch becomes a loophole. Where the fire involves a wide lateral and small vertical angle, loopholes may take the form of a long slit. Such a form will result from laying logs or fascines lengthwise on the parapet, supported at intervals by sods or other material, Fig. 31, or small poles covered with earth may be used, Fig. 30.
1154. Overhead cover. This usually consists of a raised platform of some kind covered with earth. It is frequently combined with horizontal cover in a single structure, which protects the top and exposed side. The supporting platform will almost always be of wood and may vary from brushwood or light poles to heavy timbers and plank. It is better, especially with brush or poles, to place a layer of sods, grass down, or straw, or grain sacks over the platform before putting on the earth, to prevent the latter from sifting through.
Fig. 32 Fig. 32 Fig. 34 Fig. 34 Fig. 33 Fig. 33 Fig. 35 Fig. 35 Types of overhead cover.The thickness of overhead cover depends upon the class of fire against which protection is desired, and is sometimes limited by the vertical space available, since it must afford headroom beneath, and generally should not project above the nearest natural or artificial horizontal cover. For splinter proofs a layer of earth 6 to 8 ins. thick on a support of brush or poles strong enough to hold it up will suffice if the structure is horizontal. If the front is higher than the rear, less thickness is necessary; if the rear is higher than the front, more is required. For bombproofs a minimum thickness of 6 ins. of timber and 3 ft. of earth is necessary against field and siege guns, or 12 ins. timber and 6 ft. of earth against the howitzers and mortars of a heavy siege train, not exceeding 6 inches in caliber.
In determining the area of overhead cover to be provided, allow 6 sq. ft. per man for occupancy while on duty only, or 12 sq. ft. per man for continuous occupancy not of long duration. For long occupation 18 to 20 sq. ft. per man should be provided.
It is not practicable to give complete cover to rifle positions that will successfully withstand the heavy artillery of today. The use of overhead cover is usually limited to that sufficient for protection against rifle fire, machine gun fire, and shrapnel.
1155. Cover trenches are constructed to provide safe cover for the supports or reinforcements of the fire trenches or to provide cooking and resting facilities for the garrison of the neighboring fire trenches. The important point in cover trenches is safety. They vary in design from the simple rectangular trenches to elaborately constructed trenches having overhead cover, kitchens, shelters, latrines, dressing stations, etc. Cover trenches must not be mistaken for a secondary position, they are cover for the firing line, supports and reserves until they are required in the fire trenches. The cover trench requires a depth of at least 6 feet to protect men standing. Greater depths may be used when necessary. Fig. 36 is a section of an open cover trench and Fig. 37 of a closed one. This section may be used for a communicating trench. Fig. 38 shows a cover trench close to a fire trench. The character of overhead cover for trenches is shown in the diagrams under overhead cover. The distance of the cover trenches varies with the situation. The experience of the European war places the cover trenches from 15 to 50 yards in rear of the fire trenches. These trenches furnish shelter for at least 2/3 of the firing line and supports.
Fig. 37 Fig. 37 Fig. 38 Fig. 38
The reserves are furnished yet more elaborate shelter, with plenty of room for the men to lie down and rest and when practicable, bathing facilities are provided.
1156. Dugouts. An elaborate system of dugouts has developed along the lines occupied by the troops in the European war. These dugouts are located from 14 to 40 feet below the ground and are reached by stairs in timbered passage ways. At the foot of the stairs a tunnel or corridor runs forward and on either side or at the end, rooms have been dug out varying in size. Most of these rooms have been timbered and lined. Many are electrically lighted. In some of these underground shelters, accommodations for several hundred men have been prepared with all of the necessary facilities for making them comfortable. It must be understood that such elaborate preparations can only be made when troops face each other in trenches where operations have developed into practically a siege.
1157. Communicating trenches. These trenches as the name implies are for the purpose of providing safe communication between the cover and fire trenches. They may be also constructed just in rear of a series of fire trenches to provide a means of communication from one to the other. Communicating trenches also extend to the rear of the cover trenches and provide safe passage to fresh troops or supplies. These trenches are usually laid out in zig zag or curved lines (Fig. 39), to prevent enfilade fire from sweeping them. As a general rule excavated earth is placed on both sides of the trench to afford protection, the depth is usually from 6 to 7 feet. (Fig. 15) shows a typical communicating trench.
Typical Passage Trench from Supports to Firing Line.
(From Field Entrenchments—Solano)
1158. Lookouts. To enable the garrison of a trench to get the greatest amount of comfort and rest, a lookout should be constructed and a sentinel stationed therein.
The simplest form would consist of two sandbags placed on the parapet and splayed so as to give the required view, and carefully concealed.
Better forms may be constructed, with one side resting on the berm by using short uprights with overhead cover,
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